THE ARGININE AND PREARGININE GROUPS IN EDESTIN.

Science.gov (United States)

Simms, H S

1930-09-20

The author corroborates the data of Schmidt showing that the dissociation index of the third group of arginine is pK(3)' = 12.5. New titration data of edestin have been obtained in very alkaline solutions and show that there is a corresponding group with a titration index of pG' = 12.0, but present in much less quantity than can account for the arginine found on hydrolysis. The data support the theory that the combination of strong base or strong acid with proteins is produced by the formation of salts with the "extra groups" of those trivalent amino acids which can be isolated from the protein, with the exception of arginine. Arginine contributes to the titration curve in much smaller amount than is found on hydrolysis. This deficiency in the arginine group may be accounted for by the basic group in proteins having a titration index of pG' = 3.8 to 4.6 (depending on the protein), which apparently yields arginine on hydrolysis, and may properly be called prearginine.

Is automatic CPAP titration as effective as manual CPAP titration in OSAHS patients? A meta-analysis.

Science.gov (United States)

Gao, Weijie; Jin, Yinghui; Wang, Yan; Sun, Mei; Chen, Baoyuan; Zhou, Ning; Deng, Yuan

2012-06-01

It is costly and time-consuming to conduct the standard manual titration to identify an effective pressure before continuous positive airway pressure (CPAP) treatment for obstructive sleep apnea (OSA) patients. Automatic titration is cheaper and more easily available than manual titration. The purpose of this systematic review was to evaluate the effect of automatic titration in identifying a pressure and on the improvement of apnea/hyponea index (AHI) and somnolence, the change of sleep quality, and the acceptance and compliance of CPAP treatment, compared with the manual titration. A systematic search was made of the PubMed, EMBASE, Cochrane Library, SCI, China Academic Journals Full-text Databases, Chinese Biomedical Literature Database, Chinese Scientific Journals Databases and Chinese Medical Association Journals. Randomized controlled trials comparing automatic titration and manual titration were reviewed. Studies were pooled to yield odds ratios (OR) or mean differences (MD) with 95% confidence intervals (CI). Ten trials involving 849 patients met the inclusion criteria. It is hard to identify a trend in the pressures determined by either automatic or manual titration. Automatic titration can improve the AHI (MD = 0.03/h, 95% CI = -4.48 to 4.53) and Epworth sleepiness scale (SMD = -0.02, 95% CI = -0.34 to 0.31,) as effectively as the manual titration. There is no difference between sleep architecture under automatic titration or manual titration. The acceptance of CPAP treatment (OR = 0.96, 95% CI = 0.60 to 1.55) and the compliance with treatment (MD = -0.04, 95% CI = -0.17 to 0.10) after automatic titration is not different from manual titration. Automatic titration is as effective as standard manual titration in improving AHI, somnolence while maintaining sleep quality similar to the standard method. In addition, automatic titration has the same effect on the acceptance and compliance of CPAP treatment as manual titration. With the potential advantage

On the nature of oxygen-containing surface groups on carbon nanofibers and their role for platinum deposition—an xps and titration study

NARCIS (Netherlands)

Plomp, A.J.; Su, D.S.; de Jong, K.P.; Bitter, J.H.

2009-01-01

XPS and acid−base titrations were used to investigate the nature and stability of oxygen-containing surface groups on carbon nanofibers (CNF) and platinum-containing CNF. During heat treatments in inert atmosphere at 973 K all acidic (carboxylic) oxygen surface groups were removed for CNF.

TAPIR: a device for automatic titration with incremental weighing of the titration reagent

International Nuclear Information System (INIS)

Ganivet, Michel

TAPIR is a titration device enabling automatic analyses with weighting of the titration reagent. The titration method used can be based on potentiometry, amperometry, color indicator change... The reproducibility is about 3.10 -4 [fr

LIGHT TITRATIONS

Science.gov (United States)

Field, John; Baas-Becking, Lourens G. M.

1926-01-01

1. The usefulness of the radiomicrometer in titration work has been pointed out. The authors suggest that light titration may also be used where a reaction mixture changes its absorption in the (near) infra-red. 2. The applicability of this method to the starch-iodine reaction has been demonstrated. PMID:19872266

Clinical, polysomnographic, and CPAP titration features of obstructive sleep apnea: Mixed versus purely obstructive type.

Science.gov (United States)

Lee, Sang-Ahm; Lee, Gha-Hyun; Chung, Yoo-Sam; Kim, Woo Sung

2015-08-15

To determine whether obstructive sleep apnea syndrome (OSAS) patients with mixed sleep apnea (MSA) have different clinical, polysomnographic, and continuous positive airway pressure (CPAP) titration findings compared to OSAS patients without MSA. We retrospectively reviewed the records of OSAS patients who had undergone CPAP titration and categorized them into pure-OSA and mixed-OSA groups. Demographic features, daytime sleepiness, and apnea severity were compared between the two groups using univariate and multivariate analyses. CPAP titration findings were also compared between the two groups. One hundred and ninety-five subjects (n=126 pure-OSA; n=69 mixed-OSA) were included in the analysis. Compared to the pure-OSA group, the mixed-OSA group had a higher percentage of males (p=0.003) and a higher body mass index (p=0.044), Epworth Sleepiness Scale score (p=0.028), and apnea-hypopnea index (AHI) (ptitration, and a higher titrated pressure than the pure-OSA group. Severe OSA, older age, male sex, obesity, and daytime sleepiness were related to mixed-OSA. Complex sleep apnea, less optimal titration, and a higher titrated CPAP were also associated with MSA in OSAS patients. Copyright © 2015 Elsevier B.V. All rights reserved.

Optimal level of continuous positive airway pressure: auto-adjusting titration versus titration with a predictive equation.

Science.gov (United States)

Choi, Ji Ho; Jun, Young Joon; Oh, Jeong In; Jung, Jong Yoon; Hwang, Gyu Ho; Kwon, Soon Young; Lee, Heung Man; Kim, Tae Hoon; Lee, Sang Hag; Lee, Seung Hoon

2013-05-01

The aims of the present study were twofold. We sought to compare two methods of titrating the level of continuous positive airway pressure (CPAP) - auto-adjusting titration and titration using a predictive equation - with full-night manual titration used as the benchmark. We also investigated the reliability of the two methods in patients with obstructive sleep apnea syndrome (OSAS). Twenty consecutive adult patients with OSAS who had successful, full-night manual and auto-adjusting CPAP titration participated in this study. The titration pressure level was calculated with a previously developed predictive equation based on body mass index and apnea-hypopnea index. The mean titration pressure levels obtained with the manual, auto-adjusting, and predictive equation methods were 9.0 +/- 3.6, 9.4 +/- 3.0, and 8.1 +/- 1.6 cm H2O,respectively. There was a significant difference in the concordance within the range of +/- 2 cm H2O (p = 0.019) between both the auto-adjusting titration and the titration using the predictive equation compared to the full-night manual titration. However, there was no significant difference in the concordance within the range of +/- 1 cm H2O (p > 0.999). When compared to full-night manual titration as the standard method, auto-adjusting titration appears to be more reliable than using a predictive equation for determining the optimal CPAP level in patients with OSAS.

Persistent benefits of slow titration of paroxetine in a six-month follow-up.

Science.gov (United States)

Olgiati, Paolo; Serretti, Alessandro

2015-09-01

Paroxetine titration may be difficult in older individuals as they are more sensitive to side effects. The current study extends to 6 months our previously published report in which paroxetine was started at 2.5 mg/day and slowly increased by 2.5 mg on alternate days (slow titration) or rapidly titrated to target dose from 10 mg/day (standard titration) in a naturalistic setting. Here, the follow-up period was extended to 26 weeks. We performed an intent-to-treat analysis of 47 subjects from the original sample (major depressive disorder and/or generalized anxiety disorder (GAD); >60 years of age). Missing evaluations were replaced by last observations carried forward. GAD was included as a stratification factor. Patients in whom paroxetine was slowly up-titrated were more likely to remit (84.0% vs 54.5%; p = 0.028) and had lower core depression (p = 0.0015) and psychic anxiety levels (p = 0.006) after 26 weeks. Dropout rate was 20% in the slow titration group compared with 77.3% in the standard titration arm (p titration groups in the subsample without GAD. Despite some limitations, these findings suggest that paroxetine treatment should be started at lower doses in older depressed patients and slowly up-titrated. This strategy would allow to increase antidepressant response and the likelihood of completing treatment cycle in patients with high anxiety levels and GAD comorbidity. Copyright © 2015 John Wiley & Sons, Ltd.

Automated uranium titration system

International Nuclear Information System (INIS)

Takahashi, M.; Kato, Y.

1983-01-01

An automated titration system based on the Davies-Gray method has been developed for accurate determination of uranium. The system consists of a potentiometric titrator with precise burettes, a sample changer, an electronic balance and a desk-top computer with a printer. Fifty-five titration vessels are loaded in the sample changer. The first three contain the standard solution for standardizing potassium dichromate titrant, and the next two and the last two contain the control samples for data quality assurance. The other forty-eight measurements are carried out for sixteen unknown samples. Sample solution containing about 100 mg uranium is taken in a titration vessel. At the pretreatment position, uranium (VI) is reduced to uranium (IV) by iron (II). After the valency adjustment, the vessel is transferred to the titration position. The rate of titrant addition is automatically controlled to be slower near the end-point. The last figure (0.01 mL) of the equivalent titrant volume for uranium is calculated from the potential change. The results obtained with this system on 100 mg uranium gave a precision of 0.2% (RSD,n=3) and an accuracy of better than 0.1%. Fifty-five titrations are accomplished in 10 hours. (author)

Clozapine Titration for People in Early Psychosis: A Chart Review and Treatment Guideline.

Science.gov (United States)

Ballon, Jacob S; Ashfaq, Hera; Noordsy, Douglas L

2018-06-01

The use of clozapine, particularly in young people, is often limited by early treatment-emergent adverse effects including drowsiness and lethargy. Concerns about adverse effects, medication adherence, and the need for blood monitoring often impede the use of clozapine in this population, leading to repeated trials of less effective medications. Current clozapine dosing recommendations are based on people further in the course of their illness and thus reflect different responsiveness and sensitivities to antipsychotic medication. As such, there is a need for evidence-based guidelines for titration and dosing of clozapine among people in early psychosis. We performed a chart review of 14 people treated with clozapine within our early psychosis team. Data regarding dose titration, response, time to discontinuation, symptom severity, weight gain, and other adverse effects were gathered at clozapine initiation, 3 months, and last available visit on clozapine. People treated with slow titration within their first year of psychosis onset achieved sustained response at very low maintenance doses (mean dose = 81 mg/d, mean duration of treatment = 200 weeks) compared with slow titration with longer duration of illness (mean dose = 350 mg/d, mean duration of treatment = 68 weeks) or standard dose titration in early psychosis (mean dose = 112 mg/d, mean duration of treatment = 38 weeks). The most common adverse effects in all groups were weight gain and sedation, with the groups requiring higher mean doses reporting a broader range of adverse effects. There was no apparent difference in the clinical global impression for severity or improvement between the slow titration and standard titration groups in people with early psychosis. These observations are synthesized into a proposed treatment guideline for use of clozapine among people in early psychosis. We describe development of a slow titration approach to initiating clozapine among people in early psychosis. This

[Comparison of different continuous positive airway pressure titration methods for obstructive sleep apnea hypopnea syndrome].

Science.gov (United States)

Li, Jingjing; Ye, Jingying; Zhang, Peng; Kang, Dan; Cao, Xin; Zhang, Yuhuan; Ding, Xiu; Zheng, Li; Li, Hongguang; Bian, Qiuli

2014-10-01

To explore whether there were differences between the results of automatic titration and the results of manual titration for positive airway pressure treatment in patients with obstructive sleep apnea hypopnea syndrome (OSAHS) and its influencing factors, the results might provide a theoretical basis for the rational use of two pressure titration methods. Sixty one patients with OSAHS were included in this study. All patients underwent a manual titration and an automatic titration within one week. The clinical informations, polysomnography data, and the results of both two titration of all patients were obtained for analysis. The overall apnea/hypopnea index was (63.1 ± 17.7)/h, with a range of 14.9/h to 110.4/h. The treatment pressure of manual titration was (8.4 ± 2.1) cmH(2)O, which was significantly lower than the treatment pressure of automatic titration, (11.5 ± 2.7) cmH(2)O (t = -9.797, P titration and manual titration), it was found that the pressure of automatic titration was significantly higher in patients with a ΔP > 3 cmH(2)O than in patients with a ΔP ≤ 3 cmH(2)O, which was (13.3 ± 2.3) cmH(2)O vs (10.0 ± 2.0) cmH(2)O (t = -6.159, P titration between these two groups, which was (8.6 ± 2.4) cmH(2)O vs (8.3 ± 2.0)cmH(2)O (P > 0.05). There was no significant difference in age, body mass index, neck circumference, abdomen circumference, apnea hypopnea index, and arterial oxygen saturation between these two groups. The treatment pressure of automatic titration is usually higher than that of manual titration. For patients with a high treatment pressure which is derived from automatic titration, a suggestion about manual titration could be given to decrease the potential treatment pressure of continuous positive airway pressure, which may be helpful in improving the comfortableness and the compliance of this treatment.

Determination of the protonation enthalpy of humic acid by calorimetric titration technique

International Nuclear Information System (INIS)

Kimuro, Shingo; Kirishima, Akira; Sato, Nobuaki

2015-01-01

Graphical abstract: The thermodynamic quantities of protonation of humic acid were determined by the combination of potentiometric titration and calorimetric titration. It was observed that the protonation enthalpy and Gibbs free energy had been affected by pH of solution. As a result, the thermodynamics of the protonation reaction of humic acid is influenced by the polyelectrolyte effect and the heterogeneity. - Highlights: • We applied calorimetric titration technique to the protonation of humic acid. • The thermodynamic quantities of protonation of humic acid were determined. • The protonation enthalpy of humic acid is affected by the heterogeneity. • Gibbs free energy of the protonation is affected by the polyelectrolyte effect. - Abstract: In this study, the calorimetric titration technique was used to determine the protonation enthalpy of two reference humic acids and polyacrylic acid. First, we obtained the apparent protonation constant of two kinds of humic acid purchased from IHSS (International Humic Substances Society) and polyacrylic acid by potentiometric titration. Second, we obtained the protonation enthalpy of them by calorimetric titration. The protonation enthalpy of humic acid was affected by pH and the ionic strength of bulk solution. From the comparison of ΔH between humic acid and polyacrylic acid, it was concluded that the pH dependence of ΔH is attributed to the heterogeneity of humic acid. And ΔH of phenolic hydroxyl group in humic acid is strongly influenced by the electric double layer of humic acid’s surface. This is considered to be a reason of the ionic strength dependence of ΔH. On the other hand, Gibbs free energy of the protonation of humic acid is affected by the electrostatic attraction with the progress of dissociation of functional groups such as carboxyl group and phenolic hydroxyl group. Consequently, the thermodynamics of the protonation of humic acid is affected by the polyelectrolyte effect and the

Evaluation of modified boehm titration methods for use with biochars.

Science.gov (United States)

Fidel, Rivka B; Laird, David A; Thompson, Michael L

2013-11-01

The Boehm titration, originally developed to quantify organic functional groups of carbon blacks and activated carbons in discrete pK ranges, has received growing attention for analyzing biochar. However, properties that distinguish biochar from carbon black and activated carbon, including greater carbon solubility and higher ash content, may render the original Boehm titration method unreliable for use with biochars. Here we use seven biochars and one reference carbon black to evaluate three Boehm titration methods that use (i) acidification followed by sparging (sparge method), (ii) centrifugation after treatment with BaCl (barium method), and (iii) a solid-phase extraction cartridge followed by acidification and sparging (cartridge method) to remove carbonates and dissolved organic compounds (DOC) from the Boehm extracts before titration. Our results for the various combinations of Boehm reactants and methods indicate that no one method was free of bias for all three Boehm reactants and that the cartridge method showed evidence of bias for all pK ranges. By process of elimination, we found that a combination of the sparge method for quantifying functional groups in the lowest pK range (∼5 to 6.4), and the barium method for quantifying functional groups in the higher pK ranges (∼6.4 to 10.3 and ∼10.3 to 13) to be free of evidence for bias. We caution, however, that further testing is needed and that all Boehm titration results for biochars should be considered suspect unless efforts were undertaken to remove ash and prevent interference from DOC. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Proton migration along the membrane surface in the absence of charged or titratable groups

International Nuclear Information System (INIS)

Springer, A.

2011-01-01

Proton diffusion along membrane surfaces is thought to be essential for many cellular processes such as energy transduction. For example, proton diffusion along membrane surfaces is considered to be the dominant mechanism of proton exchange between membrane sites of high and low proton concentrations. For the investigation of this mechanism, kinetic experiments on proton diffusion are evaluated to determine the ability of lipid membranes to retain protons on their surfaces. Experiments on different lipid bilayer membranes (DPhPC, DPhPE and GMO) are performed under the influence of two types of mobile buffer molecules (Capso, NH4CL). During these experiments the surface diffusion of photolytically released protons is visualized in terms of fluorescence changes of a lipid bound pH-sensitive dye (DHPE +fluorescein). The protons under investigation are released by flash photolysis of a hydrophobic caged compound (DMCM, caged diethyl phosphate). The experimental data confirm the existence of an energy barrier, which prevents the protons from escaping into the bulk. So far this effect was attributed to the proton binding to titrateable groups (e.g. ethanolamine) or electrostatic forces created by charged moieties (e.g. phosphate groups) on the membrane/water interface. However, upon removal of the titrateable groups and charged moieties from the membrane surface, a significant energy barrier remained as indicated by the experiments with glycerol monooleate (GMO) bilayers. To estimate the size of the barrier a semi-analytical model is presented that describes the two and three dimensional proton diffusion and the related physical and chemical processes. Common models describe surface proton diffusion as a series of subsequent hopping processes between membrane-anchored buffer molecules. Our experiments provide evidence for an alternative model. We released membrane-bound caged protons by UV flashes and monitored their arrival at distant sites s by fluorescence

Titration Curves: Fact and Fiction.

Science.gov (United States)

Chamberlain, John

1997-01-01

Discusses ways in which datalogging equipment can enable titration curves to be measured accurately and how computing power can be used to predict the shape of curves. Highlights include sources of error, use of spreadsheets to generate titration curves, titration of a weak acid with a strong alkali, dibasic acids, weak acid and weak base, and…

Axitinib with or without dose titration for first-line metastatic renal-cell carcinoma: a randomised double-blind phase 2 trial.

Science.gov (United States)

Rini, Brian I; Melichar, Bohuslav; Ueda, Takeshi; Grünwald, Viktor; Fishman, Mayer N; Arranz, José A; Bair, Angel H; Pithavala, Yazdi K; Andrews, Glen I; Pavlov, Dmitri; Kim, Sinil; Jonasch, Eric

2013-11-01

Population pharmacokinetic data suggest axitinib plasma exposure correlates with efficacy in metastatic renal-cell carcinoma. Axitinib dose titration might optimise exposure and improve outcomes. We prospectively assessed the efficacy and safety of axitinib dose titration in previously untreated patients with metastatic renal-cell carcinoma. In this randomised, double-blind, multicentre, phase 2 study, patients were enrolled from 49 hospitals and outpatient clinics in the Czech Republic, Germany, Japan, Russia, Spain, and USA. Patients with treatment-naive metastatic renal-cell carcinoma received axitinib 5 mg twice daily during a 4 week lead-in period. Those patients with blood pressure 150/90 mm Hg or lower, no grade 3 or 4 treatment-related toxic effects, no dose reductions, and no more than two antihypertensive drugs for 2 consecutive weeks were stratified by Eastern Cooperative Oncology Group performance status (0 vs 1), and then randomly assigned (1:1) to either masked titration with axitinib to total twice daily doses of 7 mg, and then 10 mg, if tolerated, or placebo titration. Patients who did not meet these criteria continued without titration. The primary objective was comparison of the proportion of patients achieving an objective response between randomised groups. Safety analyses were based on all patients who received at least one dose of axitinib. Between Sept 2, 2009, and Feb 28, 2011, we enrolled 213 patients, of whom 112 were randomly assigned to either the axitinib titration group (56 patients) or the placebo titration group (56 patients). 91 were not eligible for titration, and ten withdrew during the lead-in period. 30 patients (54%, 95% CI 40-67) in the axitinib titration group had an objective response, as did 19 patients (34%, 22-48]) in the placebo titration group (one-sided p=0·019). 54 (59%, 95% CI 49-70) of non-randomised patients achieved an objective response. Common grade 3 or worse, all-causality adverse events in treated patients

Axitinib with or without dose titration for first-line metastatic renal-cell carcinoma: a randomised double-blind phase 2 trial

Science.gov (United States)

Rini, Brian I; Melichar, Bohuslav; Ueda, Takeshi; GrÜnwald, Viktor; Fishman, Mayer N; Arranz, José A; Bair, Angel H; Pithavala, Yazdi K; Andrews, Glen I; Pavlov, Dmitri; Kim, Sinil; Jonasch, Eric

2014-01-01

Summary Background Population pharmacokinetic data suggest axitinib plasma exposure correlates with efficacy in metastatic renal-cell carcinoma. Axitinib dose titration might optimise exposure and improve outcomes. We prospectively assessed the efficacy and safety of axitinib dose titration in previously untreated patients with metastatic renal-cell carcinoma. Methods In this randomised, double-blind, multicentre, phase 2 study, patients were enrolled from 49 hospitals and outpatient clinics in the Czech Republic, Germany, Japan, Russia, Spain, and USA. Patients with treatment-naive metastatic renal-cell carcinoma received axitinib 5 mg twice daily during a 4 week lead-in period. Those patients with blood pressure 150/90 mm Hg or lower, no grade 3 or 4 treatment-related toxic effects, no dose reductions, and no more than two antihypertensive drugs for 2 consecutive weeks were stratified by Eastern Cooperative Oncology Group performance status (0 vs 1), and then randomly assigned (1:1) to either masked titration with axitinib to total twice daily doses of 7 mg, and then 10 mg, if tolerated, or placebo titration. Patients who did not meet these criteria continued without titration. The primary objective was comparison of the proportion of patients achieving an objective response between randomised groups. Safety analyses were based on all patients who received at least one dose of axitinib. This ongoing trial is registered with ClinicalTrials.gov, number NCT00835978. Findings Between Sept 2, 2009, and Feb 28, 2011, we enrolled 213 patients, of whom 112 were randomly assigned to either the axitinib titration group (56 patients) or the placebo titration group (56 patients). 91 were not eligible for titration, and ten withdrew during the lead-in period. 30 patients (54%, 95% CI 40–67) in the axitinib titration group had an objective response, as did 19 patients (34%, 22–48]) in the placebo titration group (one-sided p=0·019). 54 (59%, 95% CI 49–70) of non

Potentiometric titration of plutonium

International Nuclear Information System (INIS)

Silver, G.L.

1978-01-01

In the potentiometric titration of plutonium(III), it has been customary to take the equivalence point as the inflection point on a plot of potential vs. volume of titrant. It have not been, however, demonstrated, that the stoichiometric end point corresponds to the inflection point. Suggestions are made according to which these points may not correspond in the potentiometric titration of plutonium(III), as these titrations are ordinarily concluded in a period of time which is short compared to the time required for valence state rearrangement through disproportionation. (T.G.)

Acid-base titrations of functional groups on the surface of the thermophilic bacterium Anoxybacillus flavithermus: comparing a chemical equilibrium model with ATR-IR spectroscopic data.

Science.gov (United States)

Heinrich, Hannah T M; Bremer, Phil J; Daughney, Christopher J; McQuillan, A James

2007-02-27

Acid-base functional groups at the surface of Anoxybacillus flavithermus (AF) were assigned from the modeling of batch titration data of bacterial suspensions and compared with those determined from in situ infrared spectroscopic titration analysis. The computer program FITMOD was used to generate a two-site Donnan model (site 1: pKa = 3.26, wet concn = 2.46 x 10(-4) mol g(-1); site 2: pKa = 6.12, wet concn = 6.55 x 10(-5) mol g(-1)), which was able to describe data for whole exponential phase cells from both batch acid-base titrations at 0.01 M ionic strength and electrophoretic mobility measurements over a range of different pH values and ionic strengths. In agreement with information on the composition of bacterial cell walls and a considerable body of modeling literature, site 1 of the model was assigned to carboxyl groups, and site 2 was assigned to amino groups. pH difference IR spectra acquired by in situ attenuated total reflection infrared (ATR-IR) spectroscopy confirmed the presence of carboxyl groups. The spectra appear to show a carboxyl pKa in the 3.3-4.0 range. Further peaks were assigned to phosphodiester groups, which deprotonated at slightly lower pH. The presence of amino groups could not be confirmed or discounted by IR spectroscopy, but a positively charged group corresponding to site 2 was implicated by electrophoretic mobility data. Carboxyl group speciation over a pH range of 2.3-10.3 at two different ionic strengths was further compared to modeling predictions. While model predictions were strongly influenced by the ionic strength change, pH difference IR data showed no significant change. This meant that modeling predictions agreed reasonably well with the IR data for 0.5 M ionic strength but not for 0.01 M ionic strength.

Potentiometric titrations in anhydrous acetic acid

International Nuclear Information System (INIS)

Le Port, L.

1966-03-01

The method used for studying anhydrous acetic acid is potentiometry with a glass electrode. We have in this way studied the titration of common inorganic acids (HClO 4 - HBr - H 2 SO 4 - HCl - HNO 3 - H 3 PO 4 ) and of some metallic salts. Furthermore we have shown that complex acids are formed between HCl and some metallic chlorides. An analysis of the titration curves for the inorganic acids against pyridinium chloride has made it possible to calculate a certain number of values for the dissociation pK of these acids and of the corresponding pyridinium salts. The titration of metallic perchlorates constitutes a method of studying the stability of acetates; we have thus been able to draw up a classification for some of these acetates. The metallic chlorides studied fall into two groups according to their behaviour in weak or strong acids. The differences have been explained on the basis of the role played by solvolysis. In the third part we have studied the acidic properties of mixtures of HCl with certain metallic chlorides. This work has demonstrated the existence, in certain cases, of acid complexes of the type (HCl) m MCl n . (author) [fr

Potentiometric titration with polarized electrodes

International Nuclear Information System (INIS)

Chikryzova, E.G.

1977-01-01

Based on the analysis of the works carried out during 1911-75 consideration is given to the present state of the method of potentiometric titration with polarized electrodes. The material is generalized in the tabular form indicating the elments of interest, titration conditions and the objects to be analyzed. The list and classification of the potentiometric titration methods intended for determining organic and inorganic substances are presented

Evaluation of the number of ionogenic groups of inulinase by acid-base titration.

Science.gov (United States)

Kovaleva, T A; Holyavka, M G; Rezvan, S G; Kozhedub, S V

2008-06-01

Acid base titration showed that Aspergillus awamori inulinase includes 178 asparaginic and glutamic acid residues, 20 histidine, 10 serine, and 34 lysine and tyrosine residues. Denaturation temperature for this enzyme was calculated using analysis of the proportion of stabilizing and destabilizing amino acids in the molecule.

Ion-selective electrodes in potentiometric titrations; a new method for processing and evaluating titration data.

Science.gov (United States)

Granholm, Kim; Sokalski, Tomasz; Lewenstam, Andrzej; Ivaska, Ari

2015-08-12

A new method to convert the potential of an ion-selective electrode to concentration or activity in potentiometric titration is proposed. The advantage of this method is that the electrode standard potential and the slope of the calibration curve do not have to be known. Instead two activities on the titration curve have to be estimated e.g. the starting activity before the titration begins and the activity at the end of the titration in the presence of large excess of titrant. This new method is beneficial when the analyte is in a complexed matrix or in a harsh environment which affects the properties of the electrode and the traditional calibration procedure with standard solutions cannot be used. The new method was implemented both in a method of linearization based on the Grans's plot and in determination of the stability constant of a complex and the concentration of the complexing ligand in the sample. The new method gave accurate results when using titrations data from experiments with samples of known composition and with real industrial harsh black liquor sample. A complexometric titration model was also developed. Copyright © 2015 Elsevier B.V. All rights reserved.

End-point construction and systematic titration error in linear titration curves-complexation reactions

NARCIS (Netherlands)

Coenegracht, P.M.J.; Duisenberg, A.J.M.

The systematic titration error which is introduced by the intersection of tangents to hyperbolic titration curves is discussed. The effects of the apparent (conditional) formation constant, of the concentration of the unknown component and of the ranges used for the end-point construction are

Comparison of the clinical outcomes between unattended home APAP and polysomnography manual titration in obstructive sleep apnea patients.

Science.gov (United States)

Wongsritrang, Krongthong; Fueangkamloon, Sumet

2013-09-01

To compare the clinical outcomes and determine the difference in therapeutic pressure between Automatic positive airway pressure (APAP) and polysomnography manual titration. Fifty patients of obstructive sleep apnea (OSA), moderate to severe cases, were randomized into two groups of intervention: 95-percentile pressure derived from APAP titration and an optimal pressure derived from manual titration. Clinical outcomes were assessed before and after four weeks. The average 95-percentile pressure derived from APAP titration was 11.7 +/- 0.3 cmH2O with median mask leak 1.3 L/min. The average optimal pressure derived from manual titration was 8.2 +/- 0.3 cmH2O. Pearson correlation analysis showed weak positive correlation (r = 0.336, p = 0.017). The Epworth Sleepiness Score (ESS), Quality of life tests: PSQI (Pittsburg Sleep Quality Index), and SF-36 (Medical Outcomes Study 36-Item Short-Form Health Survey) were improved significantly in both groups, but there were no statistical significant differences between groups. An APAP titration is an effective method of pressure determination for conventional CPAP therapy and shows no difference in clinical outcomes comparing the standard titration.

Determining a Solubility Product Constant by Potentiometric Titration to Increase Students' Conceptual Understanding of Potentiometry and Titrations

Science.gov (United States)

Grabowski, Lauren E.; Goode, Scott R.

2017-01-01

Potentiometric titrations are widely taught in first-year undergraduate courses to connect electrochemistry, stoichiometry, and equilibria and to reinforce acid-base titrations. Students perform a potentiometric titration that is then analyzed to determine analyte concentrations and the solubility product constant of the solid species.

Benefit of slow titration of paroxetine to treat depression in the elderly.

Science.gov (United States)

Olgiati, Paolo; Bajo, Emanuele; Serretti, Alessandro

2014-11-01

Paroxetine is commonly used to treat depression in the elderly; however, titration issues have been raised. Rapid titration may lead to increased anxiety and early dropout. The aim of this cost-utility analysis was to compare the potential benefit of standard (10 mg the first day) versus slow titration (2.5 mg gradually increased). Clinical analysis was based on a naturalistic trial integrated with a decision-analytic model representing second treatments for those who initially did not respond and for dropout cases. Treatment setting was a public outpatient center for mental disorders in Italy. Service use data were estimated from best practice guidelines, whereas costs (Euros; 2012) were retrieved from Italian official sources. Slow titration approach produced 0.031 more quality-adjusted life years (remission rate: 57% vs 44% in standard titration group) at an incremental cost of €5.53 (generic paroxetine) and €54.54 (brand paroxetine syrup). Incremental cost-effectiveness ratio (ICER) values were €159 and €1768, respectively, in favor of slow titration approach. Cost-effectiveness threshold, defined as ICER titration of paroxetine in older depressed patients. However, these findings, in part based on simulated data, need to be replicated in clinical trials. Copyright © 2014 John Wiley & Sons, Ltd.

A rapid method for titration of ascovirus infectivity.

Science.gov (United States)

Han, Ningning; Chen, Zishu; Wan, Hu; Huang, Guohua; Li, Jianhong; Jin, Byung Rae

2018-05-01

Ascoviruses are a recently described family and the traditional plaque assay and end-point PCR assay have been used for their titration. However, these two methods are time-consuming and inaccurate to titrate ascoviruses. In the present study, a quick method for the determination of the titer of ascovirus stocks was developed based on ascovirus-induced apoptosis in infected insect cells. Briefly, cells infected with serial dilutions of virus (10 -2 -10 -10 ) for 24 h were stained with trypan blue. The stained cells were counted, and the percentage of nonviable cells was calculated. The stained cell rate was compared between virus-infected and control cells. The minimum-dilution group that had a significant difference compared with control and the maximum-dilution group that had no significant difference were selected and then compared each well of the two groups with the average stained cell rate of control. The well was marked as positive well if the stained cell rate was higher than the average stained cell rate of control wells; otherwise, the well was marked as negative wells. The percentage of positive wells were calculated according to the number of positive. Subsequently, the virus titer was calculated through the method of Reed and Muench. This novel method is rapid, simple, reproducible, accurate, and less material-consuming and eliminates the subjectivity of the other procedures for titrating ascoviruses. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of an automatic uranium titration system

International Nuclear Information System (INIS)

Lewis, K.

1980-01-01

The titration system utilizes the constant current coulometric titration of Goldbeck and Lerner. U(VI) is reduced to U(IV) by Fe(II). V(V) is generated to titrate the U(IV), and the titration is followed potentiometrically. The evaluation shows that the recovery of uranium is 100% at the 40-mg level. The accuracy is generally +-0.10% or better. The smallest sample weight at which reliable results were obtained was 40 mg of uranium. Time for one analysis is 15 minutes. Advantages and disadvantages of the automated titrator are listed

Automatic titrator for high precision plutonium assay

International Nuclear Information System (INIS)

Jackson, D.D.; Hollen, R.M.

1986-01-01

Highly precise assay of plutonium metal is required for accountability measurements. We have developed an automatic titrator for this determination which eliminates analyst bias and requires much less analyst time. The analyst is only required to enter sample data and start the titration. The automated instrument titrates the sample, locates the end point, and outputs the results as a paper tape printout. Precision of the titration is less than 0.03% relative standard deviation for a single determination at the 250-mg plutonium level. The titration time is less than 5 min

Cell surface groups of two picocyanobacteria strains studied by zeta potential investigations, potentiometric titration, and infrared spectroscopy.

Science.gov (United States)

Dittrich, Maria; Sibler, Sabine

2005-06-15

In order to clarify the role of picocyanobacteria in aquatic biogeochemical processes (e.g., calcite precipitation), cell surface properties need to be investigated. An experimental study of the cell surface characteristics of two Synechococcus-type unicellular autotrophic picocyanobacterial strains was carried out. One strain was isolated from Lake Plon and contained phycocyanin, the other strain came from Lago Maggiore and was rich in phycoerythrin. Potentiometric titrations were conducted to determine the different types of sites present on the bacteria cell walls. Infrared spectroscopy allowed characterization of the various functional groups (RNH(2), RCOOH, ROH, RPO(2)) and investigations of zeta potential provided insight into the isoelectrical points of the strains. Titrations reveal three distinct sites on the bacterial surfaces of phycocyanin- and phycoerythrin-rich strains with pK values of 4.8+/-0.3/5.0+/-0.2, 6.6+/-0.2/6.7+/-0.4, and 8.8+/-0.1/8.7+/-0.2, corresponding to carboxyl, phosphate, and amine groups with surface densities of 2.6+/-0.4/7.4+/-1.6 x 10(-4), 1.9+/-0.5/4.4+/-0.8 x 10(-4), and 2.5+/-0.4/4.8+/-0.7 x 10(-4) mol/g of dry bacteria. The deprotonation constants are similar to those of bacterial strains and site densities are also within an order of magnitude of other strains. The phycoerythrin-rich strain had a higher number of binding sites than the phycocyanin-rich strain. The results showed that picocyanobacteria may adsorb either calcium cations or carbonate anions and therefore strongly influence the biogeochemical cycling of calcite in pelagic systems.

Risks and Benefits of Rapid Clozapine Titration.

Science.gov (United States)

Lochhead, Jeannie D; Nelson, Michele A; Schneider, Alan L

2016-05-18

Clozapine is often considered the gold standard for the treatment of schizophrenia. Clinical guidelines suggest a gradual titration over 2 weeks to reduce the risks of adverse events such as seizures, hypotension, agranulocytosis, and myocarditis. The slow titration often delays time to therapeutic response. This raises the question of whether, in some patients, it may be safe to use a more rapid clozapine titration. The following case illustrates the potential risks associated with the use of multiple antipsychotics and rapid clozapine titration. We present the case of a young man with schizophrenia who developed life threatening neuroleptic malignant syndrome (NMS) during rapid clozapine titration and treatment with multiple antipsychotics. We were unable to find another case in the literature of NMS associated with rapid clozapine titration. This case is meant to urge clinicians to carefully evaluate the risks and benefits of rapid clozapine titration, and to encourage researchers to further evaluate the safety of rapid clozapine titration. Rapid clozapine titration has implications for decreasing health care costs associated with prolonged hospitalizations, and decreasing the emotional suffering associated with uncontrolled symptoms of psychosis. Clozapine is considered the most effective antipsychotic available thus efforts should focus on developing strategies that would allow for safest and most efficient use of clozapine to encourage its utilization for treatment resistance schizophrenia.

Risks and benefits of rapid clozapine titration

Directory of Open Access Journals (Sweden)

Jeannie D. Lochhead

2016-05-01

Full Text Available Clozapine is often considered the gold standard for the treatment of schizophrenia. Clinical guidelines suggest a gradual titration over 2 weeks to reduce the risks of adverse events such as seizures, hypotension, agranulocytosis, and myocarditis. The slow titration often delays time to therapeutic response. This raises the question of whether, in some patients, it may be safe to use a more rapid clozapine titration. The following case illustrates the potential risks associated with the use of multiple antipsychotics and rapid clozapine titration. We present the case of a young man with schizophrenia who developed life threatening neuroleptic malignant syndrome (NMS during rapid clozapine titration and treatment with multiple antipsychotics. We were unable to find another case in the literature of NMS associated with rapid clozapine titration. This case is meant to urge clinicians to carefully evaluate the risks and benefits of rapid clozapine titration, and to encourage researchers to further evaluate the safety of rapid clozapine titration. Rapid clozapine titration has implications for decreasing health care costs associated with prolonged hospitalizations, and decreasing the emotional suffering associated with uncontrolled symptoms of psychosis. Clozapine is considered the most effective antipsychotic available thus efforts should focus on developing strategies that would allow for safest and most efficient use of clozapine to encourage its utilization for treatment resistance schizophrenia.

Automated back titration method to measure phosphate

International Nuclear Information System (INIS)

Comer, J.; Tehrani, M.; Avdeef, A.; Ross, J. Jr.

1987-01-01

Phosphate was measured in soda drinks and as an additive in flour, by a back titration method in which phosphate was precipitated with lanthanum, and the excess lanthanum was titrated with fluoride. All measurements were performed using the Orion fluoride electrode and the Orion 960 Autochemistry System. In most commercial automatic titrators, the inflection point of the titration curve, calculated from the first derivative of the curve, is used to find the equivalence polar of the titration. The inflection technique is compared with a technique based on Gran functions, which uses data collected after the end point and predicts the equivalence point accordingly

Correct titration of non-drugs and some other methodological issues.

Science.gov (United States)

Beneke, M; Rasmus, W; Rød, I S; Fritze, J

1994-01-01

Doctors' prescription and dosing behaviour was investigated using data from 9 clinical trials in 550 patients treated with psychotropics. 7 trials were conducted under double- and 2 under single-blind conditions. In 3 of these trials, oral and i.m. preparations were used demanding a double-dummy design. All patients were evaluated on a weekly or 2-week basis using psychopathological rating scales (i.e. Hamilton Anxiety Scale, Hamilton Depression Scale, Clinical Global Impressions, Simpson and Angus EPS). It was found that (a) oral-medication titration was 3- to 4-fold more broad-ranging than i.m. medication titration, (b) oral placebo was titrated to the same extent as the oral investigational drugs, and (c) the titration schedule did not follow protocol requirements. Moreover, the average doses in all drug and placebo groups were the same. Concomitant medication like sleep inducers was found to be more closely related to doctors' habits than to actual medical need. Independent of trial and investigational drug, 10-33% of all patients received additional sleep inducers.

[Titration comparative study of TOPINA Tablets in patients with localization related epilepsy: double-blind comparative study by rapid and slow titration methods].

Science.gov (United States)

Kaneko, Sunao; Inoue, Yushi; Sasagawa, Mutsuo; Kato, Masaaki

2012-04-01

To compare the tolerability and efficacy of two titration methods (rapid and slow titration) for TOPINA Tablets with different dosages and periods of escalation, a double-blind comparative study was conducted in patients with localization-related epilepsy. A total of 183 patients were randomized to either rapid titration (initial dosage 100 mg/day increased by 100-200 mg at weekly intervals) or to slow titration (initial dosage 50 mg/day increased in 50 mg/day increments at weekly intervals). TOPINA Tablets were administered for 12 weeks to the maximum dosage of 400 mg/day. The incident of adverse events leading to treatment interruptions or withdrawals was 18.9% in rapid titration and 14.8% in slow titration, with no statistical significance (p = 0.554). The incident of adverse events and adverse reactions of slow titration was slightly lower than that of rapid titration. The common adverse events and adverse reactions reported in the two titration methods were comparable and were well tolerated. On the other hand, the efficacy of slow titration, percent reduction in seizure rate and responder rate, was comparable with that of rapid titration. In conclusion, there were no significant differences of therapeutic response to TOPINA Tablets between the two titration methods.

Coulometric titration at low temperatures-nonstoichiometric silver selenide

OpenAIRE

Beck, Gesa K.; Janek, Jürgen

2003-01-01

A modified coulometric titration technique is described for the investigation of nonstoichiometric phases at low temperatures. It allows to obtain titration curves at temperatures where the conventional coulometric titration technique fails because of too small chemical diffusion coefficients of the mobile component. This method for indirect coulometric titration is applied to silver selenide between -100 and 100 °C. The titration curves are analyzed on the basis of a defect chemical model an...

Functional Group and Structural Characterization of Unmodified and Functionalized Lignin by Titration, Elemental Analysis, 1H NMR and FTIR Techniques

Directory of Open Access Journals (Sweden)

Ramin Bairami Habashi

2017-11-01

Full Text Available Lignin is the second most abundant polymer in the world after cellulose. Therefore, characterization of the structure and functional groups of lignin in order to assess its potential applications in various technical fields has become a necessity. One of the major problems related to the characterization of lignin is the lack of well-defined protocols and standards. In this paper, systematic studies have been done to characterize the structure and functional groups of lignin quantitatively using different techniques such as elemental analysis, titration and 1H NMR and FTIR techniques. Lignin as a black liquor was obtained from Choka Paper Factory and it was purified before any test. The lignin was reacted with α-bromoisobutyryl bromide to calculate the number of hydroxyl and methoxyl moles. Using 1H NMR spectroscopic method on α-bromoisobutyrylated lignin (BiBL in the presence of a given amount of N,N-dimethylformamide (DMF as an internal standard, the number of moles of hydroxyl and methoxyl groups per gram of lignin was found to be 6.44 mmol/g and 6.64 mmol/g, respectively. Using aqueous titration, the number of moles of phenolic hydroxyl groups and carboxyl groups of the lignin were calculated as 3.13 mmol/g and 2.84 mmol/g, respectively. The findings obtained by 1H NMR and elemental analysis indicated to phenyl propane unit of the lignin with C9 structural formula as C9 HAl 3.84HAr2.19S0.2O0.8(OH1.38(OCH31.42. Due to poor solubility of the lignin in tetrahydrofuran (THF, acetylated lignin was used in the GPC analysis, by which number-average molecular weight  of the lignin was calculated as 992 g/mol.

The Quantitative Resolution of a Mixture of Group II Metal Ions by Thermometric Titration with EDTA. An Analytical Chemistry Experiment.

Science.gov (United States)

Smith, Robert L.; Popham, Ronald E.

1983-01-01

Presents an experiment in thermometric titration used in an analytic chemistry-chemical instrumentation course, consisting of two titrations, one a mixture of calcium and magnesium, the other of calcium, magnesium, and barium ions. Provides equipment and solutions list/specifications, graphs, and discussion of results. (JM)

Potentiometric titration of metal ions in ethanol.

Science.gov (United States)

Gibson, Graham T T; Mohamed, Mark F; Neverov, Alexei A; Brown, R S

2006-09-18

The potentiometric titrations of Zn2+, Cu2+ and 12 Ln3+ metal ions were obtained in ethanol to determine the titration constants (defined as the at which the [-OEt]/[Mx+]t ratios are 0.5, 1.5, and 2.5) and in two cases (La3+ and Zn2+) a complete speciation diagram. Several simple monobasic acids and aminium ions were also titrated to test the validity of experimental titration measurements and to establish new constants in this medium that will be useful for the preparation of buffers and standard solutions. The dependence of the titration constants on the concentration and type of metal ion and specific counterion effects is discussed. In selected cases, the titration profiles were analyzed using a commercially available fitting program to obtain information about the species present in solution, including La3+ for which a dimer model is proposed. The fitting provides the microscopic values for deprotonation of one to four metal-bound ethanol molecules. Kinetics for the La3+-catalyzed ethanolysis of paraoxon as a function of are presented and analyzed in terms of La3+ speciation as determined by the analysis of potentiometric titration curves. The stability constants for the formation of Zn2+ and Cu2+ complexes with 1,5,9-triazacyclododecane as determined by potentiometric titration are presented.

Improving medication titration in heart failure by embedding a structured medication titration plan.

Science.gov (United States)

Hickey, Annabel; Suna, Jessica; Marquart, Louise; Denaro, Charles; Javorsky, George; Munns, Andrew; Mudge, Alison; Atherton, John J

2016-12-01

To improve up-titration of medications to target dose in heart failure patients by improving communication from hospital to primary care. This quality improvement project was undertaken within three heart failure disease management (HFDM) services in Queensland, Australia. A structured medication plan was collaboratively designed and implemented in an iterative manner, using methods including awareness raising and education, audit and feedback, integration into existing work practice, and incentive payments. Evaluation was undertaken using sequential audits, and included process measures (use of the titration plan, assignment of responsibility) and outcome measures (proportion of patients achieving target dose) in HFDM service patients with reduced left ventricular ejection fraction. Comparison of the three patient cohorts (pre-intervention cohort A n=96, intervention cohort B n=95, intervention cohort C n=89) showed increase use of the titration plan, a shift to greater primary care responsibility for titration, and an increase in the proportion of patients achieving target doses of angiotensin converting enzyme inhibitors/angiotensin receptor blockers (ACEI/ARB) (A 37% vs B 48% vs C 55%, p=0.051) and beta-blockers (A 38% vs B 33% vs C 51%, p=0.045). Combining all three cohorts, patients not on target doses when discharged from hospital were more likely to achieve target doses of ACEI/ARB (pplan. A medication titration plan was successfully implemented in three HFDM services and improved transitional communication and achievement of target doses of evidence-based therapies within six months of hospital discharge. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

A new approach to flow-batch titration. A monosegmented flow titrator with coulometric reagent generation and potentiometric or biamperometric detection.

Science.gov (United States)

de Aquino, Emerson Vidal; Rohwedder, Jarbas José Rodrigues; Pasquini, Celio

2006-11-01

Monosegmented flow analysis (MSFA) has been used as a flow-batch system to produce a simple, robust, and mechanized titrator that enables true titrations to be performed without the use of standards. This paper also introduces the use of coulometry with monosegmented titration by proposing a versatile flow cell. Coulometric generation of the titrand is attractive for titrations performed in monosegmented systems, because the reagent can be added without increasing the volume of sample injected. Also, biamperomeric and potentiometric detection of titration end-points can increase the versatility of the monosegmented titrator. The cell integrates coulometric generation of the titrand with detection of end-point by potentiometry or biamperometry. The resulting titrator is a flow-batch system in which the liquid monosegment, constrained by the interfaces of the gaseous carrier stream, plays the role of a sample of known volume to be titrated. The system has been used for determination of ascorbic acid, by coulometric generation of I2 with biamperometric detection, and for determination of Fe(II), by coulometric generation of Ce(IV) with potentiometric detection of the end-point, both in feed supplements.

Potentiometric Titrations for Measuring the Capacitance of Colloidal Photodoped ZnO Nanocrystals.

Science.gov (United States)

Brozek, Carl K; Hartstein, Kimberly H; Gamelin, Daniel R

2016-08-24

Colloidal semiconductor nanocrystals offer a unique opportunity to bridge molecular and bulk semiconductor redox phenomena. Here, potentiometric titration is demonstrated as a method for quantifying the Fermi levels and charging potentials of free-standing colloidal n-type ZnO nanocrystals possessing between 0 and 20 conduction-band electrons per nanocrystal, corresponding to carrier densities between 0 and 1.2 × 10(20) cm(-3). Potentiometric titration of colloidal semiconductor nanocrystals has not been described previously, and little precedent exists for analogous potentiometric titration of any soluble reductants involving so many electrons. Linear changes in Fermi level vs charge-carrier density are observed for each ensemble of nanocrystals, with slopes that depend on the nanocrystal size. Analysis indicates that the ensemble nanocrystal capacitance is governed by classical surface electrical double layers, showing no evidence of quantum contributions. Systematic shifts in the Fermi level are also observed with specific changes in the identity of the charge-compensating countercation. As a simple and contactless alternative to more common thin-film-based voltammetric techniques, potentiometric titration offers a powerful new approach for quantifying the redox properties of colloidal semiconductor nanocrystals.

A generalized approach for the calculation and automation of potentiometric titrations Part 2. Redox Titrations

NARCIS (Netherlands)

Stur, J.; Bos, M.; van der Linden, W.E.

1984-01-01

The very fast calculation procedure described earlier is applied to calculate the titration curves of complicated redox systems. The theory is extended slightly to cover inhomogeneous redox systems. Titrations of iodine or 2,6-dichloroindophenol with ascorbic acid are described. It is shown that

An accurate potentiometric titration of 5-25 mg uranium

International Nuclear Information System (INIS)

Slanina, J.; Bakker, F.; Lingerak, W.A.

1976-01-01

A potentiometric titration of 5 to 25 mg uranium is described. Sulphamic and phosphoric acid are added to the sample (volume 1 ml), U VI is reduced to U IV by Fe 2+ and the excess of Fe 2+ is oxidized by a mixture of nitric acid, sulphamic acid and ammonium molybdate; vanadyl sulphate is added to ensure a sharp end-point of the titration. The resultant U IV is titrated automatically with 0.02500N potassiumdichromate using a platinum indicator electrode. The automatic titration is performed both with a commercial titrator (Mettler) and with an R.C.N. titrator which waits after each addition until the equilibrium is reached. Using the Mettler titrator an accuracy of 0.05% relative was reached. The R.C.N. setpoint titrator gave results with an accuracy of 0.04% relative at the 20-mg U level. Each titration takes 5 to 7 min. (author)

Up-titration of allopurinol in patients with gout.

Science.gov (United States)

Jennings, Claudine G; Mackenzie, Isla S; Flynn, Rob; Ford, Ian; Nuki, George; De Caterina, Raffaele; Riches, Philip L; Ralston, Stuart H; MacDonald, Thomas M

2014-08-01

European League against Rheumatism (EULAR) gout management guidelines recommend achieving a target urate level titration in achieving the EULAR target levels. The Febuxostat versus Allopurinol Streamlined Trial (FAST) is an ongoing multi-centre study comparing the cardiovascular safety of febuxostat and allopurinol (target recruitment: 5706 patients). Recruited patients were already taking allopurinol and the protocol required up-titration of daily allopurinol dose, in 100 mg increments, to achieve the EULAR urate target level prior to randomisation. We reviewed pre-randomisation data from the first 400 recruited and subsequently randomised FAST patients. Of 400 patients, 144 (36%) had urate levels ≥357 µmol/L at screening and required allopurinol up-titration. Higher urate levels were significantly associated with lower allopurinol dose, male sex, increased BMI, increased alcohol intake and diuretic use. Mean fall in urate levels after a single 100-mg dose increase was 71 µmol/L. The number of up-titrations required ranged from one to five (median = 1) with 65% of patients controlled after one 100-mg up-titration. Overall, 97% of up-titrated patients achieved target urate levels with median final allopurinol dose of 300 mg daily. Side effects and complications of up-titration were minimal. Overall, 36% of FAST patients were not at target urate levels and required up-titration. Allopurinol up-titration was effective in achieving urate target levels and was generally well tolerated by patients. Copyright © 2014 Elsevier Inc. All rights reserved.

Non-aqueous titration of hydroxamic acids.

Science.gov (United States)

Stamey, T W; Christian, R

1966-01-01

Benzohydroxamic acid is titrated with 0.1M tetrabutyl-anunonium hydroxide in nine non-aqueous solvents with three different indicating electrodes. The best results are obtained using dimethylformamide as solvent and platinum-platinum electrodes. Four monoprotic and three diprotic hydroxamie acids and iron(III) benzohydroxamate have been successfully titrated with this system. The effect of quantitative additions of carbon dioxide to the titrant on its apparent molarity are found to be dependent on the amount added, the strength and sample size of acid titrated and the solvent used.

A generalized approach for the calculation and automation of potentiometric titrations Part 1. Acid-Base Titrations

NARCIS (Netherlands)

Stur, J.; Bos, M.; van der Linden, W.E.

1984-01-01

Fast and accurate calculation procedures for pH and redox potentials are required for optimum control of automatic titrations. The procedure suggested is based on a three-dimensional titration curve V = f(pH, redox potential). All possible interactions between species in the solution, e.g., changes

Determination of substances by radiothermometric titration

International Nuclear Information System (INIS)

Tolgyessy, J.; Lesny, J.

1976-01-01

For determination, nitrogen is bubbled through a solution containing radioactive Kr, Xe, Rn or another aerogen in addition to the substance determined. A continuous or intermittent addition of the titrating solution results in the release of reaction heat, thus increasing the temperature of the reaction mixture, which releases a radioactive gas. Upon reaching the equivalence point, the cold titrating reagent cools the reaction mixture, thus reducing the radioactive substance release. The equivalence point lies at the point of intersection of the extended linear parts of the curve of the dependence of released radioactivity on the volume of the titrating solution added. (M.K.)

Potentiometric Titration Method for Quantitative Determination of Hydrogen Peroxide

National Research Council Canada - National Science Library

Bessette, Russell R

2005-01-01

An electrochemical potentiometric titration method that entails titration of a known volume of a catholyte containing an unknown amount of hydrogen peroxide in a titration cell having two electrodes...

Determination of milligram amounts of neptunium by potentiometric titration

International Nuclear Information System (INIS)

Ryzhinskij, M.V.; Solntseva, L.F.

1981-01-01

Two procedures of potentiometric titration of about 1 mg Np are reported which are based on its oxidation to neptunium (6) with silver (2) oxide followed by titration with iron (2) to neptunium (5) in one case and to neptunium (4) in the alternative one. The error is not greater than 0.2% rel. Ten-fold uranium excess does not interfere. Up to 1% of plutonium relative to neptunium does not interfere in the case of the titration to neptunium (5). In the titration to neptunium (4), plutonium is titrated stoichiometrically [ru

A Tabular Approach to Titration Calculations

Science.gov (United States)

Lim, Kieran F.

2012-01-01

Titrations are common laboratory exercises in high school and university chemistry courses, because they are easy, relatively inexpensive, and they illustrate a number of fundamental chemical principles. While students have little difficulty with calculations involving a single titration step, there is a significant leap in conceptual difficulty…

Symmetry Properties of Potentiometric Titration Curves.

Science.gov (United States)

Macca, Carlo; Bombi, G. Giorgio

1983-01-01

Demonstrates how the symmetry properties of titration curves can be efficiently and rigorously treated by means of a simple method, assisted by the use of logarithmic diagrams. Discusses the symmetry properties of several typical titration curves, comparing the graphical approach and an explicit mathematical treatment. (Author/JM)

Automated titration method for use on blended asphalts

Science.gov (United States)

Pauli, Adam T [Cheyenne, WY; Robertson, Raymond E [Laramie, WY; Branthaver, Jan F [Chatham, IL; Schabron, John F [Laramie, WY

2012-08-07

A system for determining parameters and compatibility of a substance such as an asphalt or other petroleum substance uses titration to highly accurately determine one or more flocculation occurrences and is especially applicable to the determination or use of Heithaus parameters and optimal mixing of various asphalt stocks. In a preferred embodiment, automated titration in an oxygen gas exclusive system and further using spectrophotometric analysis (2-8) of solution turbidity is presented. A reversible titration technique enabling in-situ titration measurement of various solution concentrations is also presented.

Randomized clinical trial of an intravenous hydromorphone titration protocol versus usual care for management of acute pain in older emergency department patients.

Science.gov (United States)

Chang, Andrew K; Bijur, Polly E; Davitt, Michelle; Gallagher, E John

2013-09-01

Opioid titration is an effective strategy for treating pain; however, titration is generally impractical in the busy emergency department (ED) setting. Our objective was to test a rapid, two-step, hydromorphone titration protocol against usual care in older patients presenting to the ED with acute severe pain. This was a prospective, randomized clinical trial of patients 65 years of age and older presenting to an adult, urban, academic ED with acute severe pain. The study was registered at http://www.clinicaltrials.gov (NCT01429285). Patients randomized to the hydromorphone titration protocol initially received 0.5 mg intravenous hydromorphone. Patients randomized to usual care received any dose of any intravenous opioid. At 15 min, patients in both groups were asked, 'Do you want more pain medication?' Patients in the hydromorphone titration group who answered 'yes' received a second dose of 0.5 mg intravenous hydromorphone. Patients in the usual care group who answered 'yes' had their ED attending physician notified, who then could administer any (or no) additional medication. The primary efficacy outcome was satisfactory analgesia defined a priori as the patient declining additional analgesia at least once when asked at 15 or 60 min after administration of the initial opioid. Dose was calculated in morphine equivalent units (MEU: 1 mg hydromorphone = 7 mg morphine). The need for naloxone to reverse adverse opioid effects was the primary safety outcome. 83.0 % of 153 patients in the hydromorphone titration group achieved satisfactory analgesia compared with 82.5 % of 166 patients in the usual care group (p = 0.91). Patients in the hydromorphone titration group received lower mean initial doses of opioids at baseline than patients in the usual care group (3.5 MEU vs. 4.7 MEU, respectively; p ≤ 0.001) and lower total opioids through 60 min (5.3 MEU vs. 6.0 MEU; p = 0.03). No patient needed naloxone. Low-dose titration of intravenous hydromorphone in increments of

Kinetics of bacterial potentiometric titrations: the effect of equilibration time on buffering capacity of Pantoea agglomerans suspensions.

Science.gov (United States)

Kapetas, Leon; Ngwenya, Bryne T; Macdonald, Alan M; Elphick, Stephen C

2011-07-15

Several recent studies have made use of continuous acid-base titration data to describe the surface chemistry of bacterial cells as a basis for accurately modelling metal adsorption to bacteria and other biomaterials of potential industrial importance. These studies do not share a common protocol; rather they titrate in different pH ranges and they use different stability criteria to define equilibration time during titration. In the present study we investigate the kinetics of bacterial titrations and test the effect they have on the derivation of functional group concentrations and acidity constants. We titrated suspensions of Pantoea agglomerans by varying the equilibration time between successive titrant additions until stability of 0.1 or 0.001 mV s(-1) was attained. We show that under longer equilibration times, titration results are less reproducible and suspensions exhibit marginally higher buffering. Fluorescence images suggest that cell lysis is not responsible for these effects. Rather, high DOC values and titration reversibility hysterisis after long equilibration times suggest that variability in buffering is due to the presence of bacterial exudates, as demonstrated by titrating supernatants separated from suspensions of different equilibration times. It is recommended that an optimal equilibration time is always determined with variable stability control and preliminary reversibility titration experiments. Copyright © 2011 Elsevier Inc. All rights reserved.

An Olfactory Indicator for Acid-Base Titrations.

Science.gov (United States)

Flair, Mark N.; Setzer, William N.

1990-01-01

The use of an olfactory acid-base indicator in titrations for visually impaired students is discussed. Potential olfactory indicators include eugenol, thymol, vanillin, and thiophenol. Titrations performed with each indicator with eugenol proved to be successful. (KR)

Simple home-made sensors for potentiometric titrations

International Nuclear Information System (INIS)

Selig, W.

1982-04-01

A sensor for potentiometric titrations was prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) and dioctyphthalate in tetrahydrofuran. The reference electrode was an Ag/AgCl single-junction electrode. The sensor was used in precipitation, acid-base, compleximetric, and redox titrations. Preparation of the coated-graphite sensor is simple and rapid. Moreover, it is quite inexpensive. A limitation is its applicability in aqueous media only, because organic solvents will dissolve the membrane. Various uncoated types of graphite have also been investigated as sensors, particularly in two applications of interest in the analysis of propellants: the titration of nitroform and perchlorate. Obviously, these sensors can be used also in nonaqueous, or partially nonaqueous media. These sensors may also find use in the potentiometric titration of fluoride vs La(III) or Th

Novel titration method for surface-functionalised silica

Energy Technology Data Exchange (ETDEWEB)

Hofen, Kai; Weber, Siegfried [Department of Biotechnology, University of Applied Sciences, Mannheim (Germany); Chan, Chiu Ping Candace [School of Advanced Manufacturing and Mechanical Engineering, Mawson Institute, University of South Australia, Mawson Lakes Blvd, Mawson Lakes 5095 (Australia); Majewski, Peter, E-mail: peter.majewski@unisa.edu.au [School of Advanced Manufacturing and Mechanical Engineering, Mawson Institute, University of South Australia, Mawson Lakes Blvd, Mawson Lakes 5095 (Australia)

2011-01-15

This paper describes three inexpensive and fast analytical methods to characterise grafted particle surfaces. The reaction of silica with (3-aminopropyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane and N-(phosphonomethyl)iminodiacetic acid hydrate, respectively, leads to NH{sub 2}-, SO{sub 3}H- or COOH-functionalised silica, which were characterised by X-ray photoelectron spectrometry and titration in nonaqueous media as well as with two titration methods in a water-based environment. In the work presented, factors influencing the titrations are pointed out and solutions are presented to overcome these limiting factors are shown.

Novel titration method for surface-functionalised silica

International Nuclear Information System (INIS)

Hofen, Kai; Weber, Siegfried; Chan, Chiu Ping Candace; Majewski, Peter

2011-01-01

This paper describes three inexpensive and fast analytical methods to characterise grafted particle surfaces. The reaction of silica with (3-aminopropyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane and N-(phosphonomethyl)iminodiacetic acid hydrate, respectively, leads to NH 2 -, SO 3 H- or COOH-functionalised silica, which were characterised by X-ray photoelectron spectrometry and titration in nonaqueous media as well as with two titration methods in a water-based environment. In the work presented, factors influencing the titrations are pointed out and solutions are presented to overcome these limiting factors are shown.

A randomised controlled trial evaluating IGF1 titration in contrast to current GH dosing strategies in children born small for gestational age

DEFF Research Database (Denmark)

Jensen, Rikke Beck; Thankamony, Ajay; O'Connell, Susan M

2014-01-01

BACKGROUND: Short children born small for gestational age (SGA) are treated with a GH dose based on body size, but treatment may lead to high levels of IGF1. The objective was to evaluate IGF1 titration of GH dose in contrast to current dosing strategies. METHODS: In the North European Small......-for-Gestational-Age Study (NESGAS), 92 short pre-pubertal children born SGA were randomised after 1 year of high-dose GH treatment (67 μg/kg per day) to three different regimens: high dose (67 μg/kg per day), low dose (35 μg/kg per day) or IGF1 titration. RESULTS: The average dose during the second year of the randomised...... trial did not differ between the IGF1 titration group (38 μg/kg per day, s.d. 0.019) and the low-dose group (35 μg/kg per day, s.d. 0.002; P=0.46), but there was a wide variation in the IGF1 titration group (range 10-80 μg/kg per day). The IGF1 titration group had significantly lower height gain (0...

Titratable acidity of beverages influences salivary pH recovery.

Science.gov (United States)

Tenuta, Livia Maria Andaló; Fernández, Constanza Estefany; Brandão, Ana Carolina Siqueira; Cury, Jaime Aparecido

2015-01-01

A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conducted in vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control) were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively) and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and pH 5.5, respectively). Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

Potentiometric titration and equivalent weight of humic acid

Science.gov (United States)

Pommer, A.M.; Breger, I.A.

1960-01-01

The "acid nature" of humic acid has been controversial for many years. Some investigators claim that humic acid is a true weak acid, while others feel that its behaviour during potentiometric titration can be accounted for by colloidal adsorption of hydrogen ions. The acid character of humic acid has been reinvestigated using newly-derived relationships for the titration of weak acids with strong base. Re-interpreting the potentiometric titration data published by Thiele and Kettner in 1953, it was found that Merck humic acid behaves as a weak polyelectrolytic acid having an equivalent weight of 150, a pKa of 6.8 to 7.0, and a titration exponent of about 4.8. Interdretation of similar data pertaining to the titration of phenol-formaldehyde and pyrogallol-formaldehyde resins, considered to be analogs for humic acid by Thiele and Kettner, leads to the conclusion that it is not possible to differentiate between adsorption and acid-base reaction for these substances. ?? 1960.

Assessment of two theoretical methods to estimate potentiometric titration curves of peptides: comparison with experiment.

Science.gov (United States)

Makowska, Joanna; Bagiñska, Katarzyna; Makowski, Mariusz; Jagielska, Anna; Liwo, Adam; Kasprzykowski, Franciszek; Chmurzyñski, Lech; Scheraga, Harold A

2006-03-09

We compared the ability of two theoretical methods of pH-dependent conformational calculations to reproduce experimental potentiometric titration curves of two models of peptides: Ac-K5-NHMe in 95% methanol (MeOH)/5% water mixture and Ac-XX(A)7OO-NH2 (XAO) (where X is diaminobutyric acid, A is alanine, and O is ornithine) in water, methanol (MeOH), and dimethyl sulfoxide (DMSO), respectively. The titration curve of the former was taken from the literature, and the curve of the latter was determined in this work. The first theoretical method involves a conformational search using the electrostatically driven Monte Carlo (EDMC) method with a low-cost energy function (ECEPP/3 plus the SRFOPT surface-solvation model, assumming that all titratable groups are uncharged) and subsequent reevaluation of the free energy at a given pH with the Poisson-Boltzmann equation, considering variable protonation states. In the second procedure, molecular dynamics (MD) simulations are run with the AMBER force field and the generalized Born model of electrostatic solvation, and the protonation states are sampled during constant-pH MD runs. In all three solvents, the first pKa of XAO is strongly downshifted compared to the value for the reference compounds (ethylamine and propylamine, respectively); the water and methanol curves have one, and the DMSO curve has two jumps characteristic of remarkable differences in the dissociation constants of acidic groups. The predicted titration curves of Ac-K5-NHMe are in good agreement with the experimental ones; better agreement is achieved with the MD-based method. The titration curves of XAO in methanol and DMSO, calculated using the MD-based approach, trace the shape of the experimental curves, reproducing the pH jump, while those calculated with the EDMC-based approach and the titration curve in water calculated using the MD-based approach have smooth shapes characteristic of the titration of weak multifunctional acids with small differences

Isothermal titration calorimetric studies of the acid-base properties of poly(N-isopropylacrylamide-co-4-vinylpyridine) cationic polyelectrolyte colloidal microgels

International Nuclear Information System (INIS)

Seidel, J.; Pinkrah, V.T.; Mitchell, J.C.; Chowdhry, B.Z.; Snowden, M.J.

2004-01-01

Isothermal titration calorimetry (ITC) and potentiometric titration were used to study the protonation properties of the 4-vinylpyridine (4-VP) moiety in cationic poly(N-isopropylacrylamide-co-4-vinylpyridine) colloidal microgels [poly(NIPAM-co-4-VP)]. Calorimetric pH titrations were performed using microgels of different 4-VP content and the influence of ionic strength and counter ions have been examined. The calorimetric titration output consists of several thermal contributions reflecting the complex nature of the interactions in the aqueous microgel dispersions. In contrast to the potentiometric results, the calorimetric titration data could not be completely described by a theoretical model solely taking into account protonation equilibria. Deviations from the proposed model correlate with swelling or shrinking of the gel particles. The calorimetric results also reveal a pronounced counter-ion effect of perchlorate compared to chloride ions. In the presence of perchlorate ions, small secondary thermal effects accompany protonation of the 4-VP moiety due, in part, to kinetically limited conformational changes in the co-polymer microgel

Potentiometric titration of free acid in uranium solutions

International Nuclear Information System (INIS)

Suh, M. Y.; Kim, W. H.; Kim, J. S.; Sohn, S. C.; Eom, T. Y.; Lee, C. H.; Jeon, Y. S.; Han, S. H.

1998-02-01

Hydrolysis properties of metal cations and fundamental principles of the potentiometric titration of free acid in aqueous solutions containing metal cations were described. The published papers and reports for the alkalimetric and acidimetric titration of free acid were surveyed, and the applicability of these titration methods to the uranium and/or plutonium solutions were discussed. This technical report also includes the various results obtained from the authors' researches to establish the alkalimetric and acidimetric titration methods for the determination of free acid in nitric acid solutions containing uranium and/or oxalic acid, and aluminum. The procedure manuals used in chemical processes and the newly prepared manuals based on the authors' researches are appended. (author). 26 refs., 54 figs

Potentiometric titration of free acid in uranium solutions

Energy Technology Data Exchange (ETDEWEB)

Suh, M. Y.; Kim, W. H.; Kim, J. S.; Sohn, S. C.; Eom, T. Y.; Lee, C. H.; Jeon, Y. S.; Han, S. H.

1998-02-01

Hydrolysis properties of metal cations and fundamental principles of the potentiometric titration of free acid in aqueous solutions containing metal cations were described. The published papers and reports for the alkalimetric and acidimetric titration of free acid were surveyed, and the applicability of these titration methods to the uranium and/or plutonium solutions were discussed. This technical report also includes the various results obtained from the authors` researches to establish the alkalimetric and acidimetric titration methods for the determination of free acid in nitric acid solutions containing uranium and/or oxalic acid, and aluminum. The procedure manuals used in chemical processes and the newly prepared manuals based on the authors` researches are appended. (author). 26 refs., 54 figs.

NBL-Davies-Gray weight titration method

International Nuclear Information System (INIS)

Hassell, C.

1981-01-01

The titration method for uranium consists of the following basic steps: reduction of U +6 to U +4 by Fe +2 ; selective oxidation of excess Fe +2 by HNO 3 with Mo +6 catalyst, all in strong phosphoric acid solution; and titration of the U +4 with standard dichromate after dilution. In this paper, detailed procedure of the NBL method, its modification to a gravimetric system or weight titration technique, and miniaturization of the NBL titrimetric method are discussed. Improved precisions and accuracy (2 to 3 times), of the gravimetric titrant delivery has made it possible to reduce the amount of uranium taken for each analysis. At present, using gravimetric delivery, most samples are titrated in the 30 to 50 mg range. Improved precision has led to investigating the possibility of a scaled-down version of the basic method so as to reduce the volume of phosphoric acid waste generated. Because all reactions are carried out in the same vessel, this method can be automated. Analysts at NBL have been able to restrict error to 0.05% or better in the 30 to 100 mg range using the basic procedure

Thermometric titration in investigation of the formation of polyanions of molybdenum(VI), tungsten(VI), vanadium(V), and chromium (VI)-I: comparison of thermometric and potentiometric titration curves.

Science.gov (United States)

Kiba, N; Takeuchi, T

1973-09-01

A new twin-cell thermometric titrator has been devised and used for thermometric titration of solutions of sodium molybdate, sodium tungstate, sodium orthovanadate, ammonium metavanadate, and potassium chromate with perchloric acid. The thermometric titration curves were compared with corresponding pH-titration curves for elucidation of the reactions occurring in the titrations. Thermometric titrimetric methods have been developed for the determination of tungsten, vanadium and chromium.

Students' integration of multiple representations in a titration experiment

Science.gov (United States)

Kunze, Nicole M.

A complete understanding of a chemical concept is dependent upon a student's ability to understand the microscopic or particulate nature of the phenomenon and integrate the microscopic, symbolic, and macroscopic representations of the phenomenon. Acid-base chemistry is a general chemistry topic requiring students to understand the topics of chemical reactions, solutions, and equilibrium presented earlier in the course. In this study, twenty-five student volunteers from a second semester general chemistry course completed two interviews. The first interview was completed prior to any classroom instruction on acids and bases. The second interview took place after classroom instruction, a prelab activity consisting of a titration calculation worksheet, a titration computer simulation, or a microscopic level animation of a titration, and two microcomputer-based laboratory (MBL) titration experiments. During the interviews, participants were asked to define and describe acid-base concepts and in the second interview they also drew the microscopic representations of four stages in an acid-base titration. An analysis of the data showed that participants had integrated the three representations of an acid-base titration to varying degrees. While some participants showed complete understanding of acids, bases, titrations, and solution chemistry, other participants showed several alternative conceptions concerning strong acid and base dissociation, the formation of titration products, and the dissociation of soluble salts. Before instruction, participants' definitions of acid, base, and pH were brief and consisted of descriptive terms. After instruction, the definitions were more scientific and reflected the definitions presented during classroom instruction.

A computer controlled potentiometric titrator for quantitative determination of uranium

International Nuclear Information System (INIS)

Verdingh, V.; Michiels, A.

1988-01-01

The modified Davies and Gray methods is frequently used for the potentiometric titration of uranium. It is based upon the reduction of U(VI) to U(IV) with a reductant (e.g. Fe ++ ) followed by a selective oxidation of the excess of reductant and subsequent titration of U(IV) with potassium dichromate (K 2 Cr 2 O 7 ). Interference from other elements is low, but the method is rather cumbersome due to the number of reactants to be added before the titration is started. The timing of these additions also plays a role. In order to render the titration less dependent on human factors and with the aim of reaching high reproducibility, a computer controlled system has been designed and set-up. Reagents are added by five computer controlled burettes. A program allows the choice of volumes and waiting times, and commands the start of the final titration which is followed by the microprocessor of the automatic potentiometric titrator. In this way a routine uranium titration can be completed in about twelve minutes. Reproducibilities of the order of ±15% are achievable in routine operation. For high precision work, the titrator is used as an end-point detector. Titrant is added manually by mass, so as to react with > 99% of the uranium. The residual uranium is then titrated automatically by colume with diluted titrant. The precision can be improved by a factor of approximately ten. (orig.)

Boehm Titration Revisited (Part II: A Comparison of Boehm Titration with Other Analytical Techniques on the Quantification of Oxygen-Containing Surface Groups for a Variety of Carbon Materials

Directory of Open Access Journals (Sweden)

Jan Schönherr

2018-04-01

Full Text Available The use of the Boehm titration (BT method as an analytical tool for the quantification of oxygen-containing surface groups is systematically investigated for oxidized carbon black, carbon nanotubes and two active carbons with specific surface areas between 60 and 1750 m2 g−1. The accuracy of the BT method is quantitatively compared with results from elemental analysis (EA, temperature programmed desorption (TPD, and X-ray photoelectron spectroscopy (XPS. Overall, the results from TPD are in line with the values obtained by BT. Both show the equal ratio of the oxygen groups to each other. Within the series of carbon samples, all methods provide similar trends for the total oxygen content yet the absolute numbers are deviating significantly. Reasons for these discrepancies are discussed and linked to the specific characteristics of the different methods. As the BT method is a solution based method, it only probes the surface fraction of the carbon that is accessible to the base solution. That means, it probes the relevant fraction for applications where carbon is in contact to aqueous solutions. Overall, the BT method can be conveniently applied to a broad range of carbon materials as long as the samples are sufficiently hydrophilic and of the enough sample amount is provided.

Non-aqueous titration of benzotrifuroxan (BTF)

Energy Technology Data Exchange (ETDEWEB)

Selig, W.

1978-01-01

This compound can be titrated potentiometrically as an acid with tetrabutylammonium hydroxide in dimethylformamide, dimethylsulfoxide, acetone, pyridine, tetramethylguanidine. The solvent of choice is dimethylformamide which yields the steepest titration curve and the lowest standard deviation. The equivalent weight of benzotrifuroxan is dependent on the solvent used indicating a strong interaction with the solvent. In dimethylformamide, the equivalent weight of benzotrifuroxan is 151.3, corresponding to 1.67 equivalents per mole.

Coulometric titration of niobium in EDTA complexing solution

International Nuclear Information System (INIS)

Pannu, S.S.

1976-01-01

Constant current coulometry of Nb in EDTA was studied employing both potentiometric and amperometric end-point techniques. The titrations were based on the oxidation of Nb(IV)-EDTA with electrogenerated Fe(III) at a graphite anode. The rate of disproportionation of Nb(IV)-EDTA was found to be slow enough not to effect the accuracy sought for the titration. The coulometric titration of Nb in EDTA was found to be more accurate than in 1F sulfuric acid. The mean error in the titrations of 4.76 to 19.65 of Nb in a volume of about 100 ml of 0.02 to 0.04F EDTA was 0.13%. It was found that Ta may be tolerated to a ratio of 1:4, Ta:Nb, in a solution containing 13 mg of Nb. (author)

Titratable acidity of beverages influences salivary pH recovery

Directory of Open Access Journals (Sweden)

Livia Maria Andaló TENUTA

2015-01-01

Full Text Available A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conducted in vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and < 0.005 mmols OH- to reach pH 5.5, respectively. Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

Impact of systolic blood pressure on the safety and tolerability of initiating and up-titrating sacubitril/valsartan in patients with heart failure and reduced ejection fraction: insights from the TITRATION study.

Science.gov (United States)

Senni, Michele; McMurray, John J V; Wachter, Rolf; McIntyre, Hugh F; Anand, Inder S; Duino, Vincenzo; Sarkar, Arnab; Shi, Victor; Charney, Alan

2018-03-01

The TITRATION trial investigated two strategies to initiate and up-titrate sacubitril/valsartan (LCZ696) to the same target dose, over a condensed (3-week) or conservative (6-week) period, in patients with heart failure with reduced ejection fraction (HFrEF) and systolic blood pressure (SBP) of ≥100 mmHg. This post hoc analysis examined the relationship between baseline SBP at screening and achievement of the target dose of sacubitril/valsartan of 97 mg/103 mg (also termed 'LCZ696 200 mg') twice per day during the study. Patients (n = 498) were categorized in four groups based on SBP at screening: 100-110 mmHg (n = 70); 111-120 mmHg (n = 93); 121-139 mmHg (n = 168) and ≥140 mmHg (n = 167). Overall, 72.7%, 76.1%, 85.6% and 82.9%, respectively, of patients in these SBP categories achieved and maintained the target dose of sacubitril/valsartan without down-titration/dose interruption over 12 weeks ('treatment success'). Compared with patients with SBP of 100-110 mmHg, rates of treatment success among patients in the higher SBP groups [111-120 mmHg (P = 0.96); 121-139 mmHg (P = 0.06) and ≥140 mmHg (P = 0.25)] did not differ significantly. A higher percentage of patients with lower SBP (100-110 mmHg) achieved treatment success with gradual up-titration (6 weeks) (∼80%) than with rapid up-titration (∼69%). Similar findings were observed with regard to 'tolerability success' (maintenance of the target dose for at least the final 2 weeks prior to study completion). Hypotension occurred more frequently in patients with lower SBP. The majority of patients (>80%) with SBP of ≥100 mmHg achieved and maintained the target dose of sacubitril/valsartan if the treatment was titrated gradually. These findings suggest that low SBP should not prevent clinicians from considering the initiation of sacubitril/valsartan. © 2017 The Authors. European Journal of Heart Failure © 2017 European Society of

Computer controlled titration with piston burette or peristaltic pump - a comparison.

Science.gov (United States)

Hoffmann, W

1996-09-01

The advantages and problems of the use of piston burettes and peristaltic pumps for dosage of titrant solutions in automatic titrations are shown. For comparison, only the dosing devices were exchanged and all other components and conditions remained unchanged. The results of continuous acid base titration show good agreement and comparable reproducibility. Potentiometric sensors (glass electrodes) with different equilibration behaviour influence the results. The capability of such electrodes was tested. Conductometric measurements allow a much faster detection because there is no equilibration of electrodes. Piston burettes should be used for titration with very high precision, titration with organic solvents and slow titrations. Peristaltic pumps seem to be more suitable for continuous titrations and long time operation without service.

Titration in the treatment of the more troubled patient.

Science.gov (United States)

Winer, J A; Ornstein, E D

2001-01-01

This article defines and discusses a modification of technique recommended by the authors in the psychoanalytic treatment of more troubled patients--a modification they call titration. Titration is defined as a conscious decision by the analyst to increase or decrease assistance (or gratification) gradually, in order to facilitate the analytic process. The authors emphasize the complexity of decisions in treatment by focusing on the decision-making processes that titration requires. Guidelines and a case vignette are presented. The authors conclude by considering some of the politics involved in the introduction of technique modifications, the salience of the titration concept, and directions for further exploration.

Potentiometric determination of milligram amounts of uranium by semiautomatic titrator

International Nuclear Information System (INIS)

Ryzhinskij, M.V.; Stepanov, A.V.; Preobrazhenskaya, L.D.; Solntseva, L.F.; Gromova, E.A.

1978-01-01

A semiautomatic titrator is described which allows gravimetriotentiometricc-p titrat mg amounts of substances. Milligram amounts of uranium (absolute contents and oxygen/uranium ratio) in U 3 O 8 were determined as an example of the titrator action. The relative standard deviation was less than 0.001

Barriers to Beta-Blocker Use and Up-Titration Among Patients with Heart Failure with Reduced Ejection Fraction.

Science.gov (United States)

Levitan, Emily B; Van Dyke, Melissa K; Loop, Matthew Shane; O'Beirne, Ronan; Safford, Monika M

2017-12-01

For patients with heart failure with reduced ejection fraction (HFrEF), guidelines recommend use of beta-blockers with gradual up-titration. However, many patients with HFrEF do not use beta-blockers and up-titration is rare. Our purpose was to identify and rank barriers to beta-blocker use and up-titration from the perspective of primary care physicians. We conducted 4 moderated, structured group discussions among 19 primary care physicians using the nominal group technique; 16 participants also completed a survey. Participants generated lists of barriers to beta-blocker use and up-titration among patients with HFrEF. Each participant had six votes with three votes assigned to the item ranked most important, two to the second most important item, and one to the third most important item. Investigators characterized items into themes. The percentage of available votes was calculated for each theme. Fifteen of 16 participating primary care physicians who completed the survey reported that management of beta-blockers was their responsibility. Treatment/side effects, particularly hypotension, were identified as the most important barrier for beta-blocker use (72% of available votes) followed by polypharmacy (11%), healthcare system barriers (10%), and comorbidities (6%). Barriers to up-titration included treatment/side effects (49% of available votes), patient communication/buy-in (21%), polypharmacy (13%), and healthcare system barriers (8%). Many barriers to guideline concordant use of beta-blockers among patients with HFrEF identified by primary care providers are not readily modifiable. Addressing these barriers may require development, testing, and dissemination of protocols for beta-blocker initiation and up-titration that are safe and appropriate in primary care.

Empiric auto-titrating CPAP in people with suspected obstructive sleep apnea.

Science.gov (United States)

Drummond, Fitzgerald; Doelken, Peter; Ahmed, Qanta A; Gilbert, Gregory E; Strange, Charlie; Herpel, Laura; Frye, Michael D

2010-04-15

Efficient diagnosis and treatment of obstructive sleep apnea (OSA) can be difficult because of time delays imposed by clinic visits and serial overnight polysomnography. In some cases, it may be desirable to initiate treatment for suspected OSA prior to polysomnography. Our objective was to compare the improvement of daytime sleepiness and sleep-related quality of life of patients with high clinical likelihood of having OSA who were randomly assigned to receive empiric auto-titrating continuous positive airway pressure (CPAP) while awaiting polysomnogram versus current usual care. Serial patients referred for overnight polysomnography who had high clinical likelihood of having OSA were randomly assigned to usual care or immediate initiation of auto-titrating CPAP. Epworth Sleepiness Scale (ESS) scores and the Functional Outcomes of Sleep Questionnaire (FOSQ) scores were obtained at baseline, 1 month after randomization, and again after initiation of fixed CPAP in control subjects and after the sleep study in auto-CPAP patients. One hundred nine patients were randomized. Baseline demographics, daytime sleepiness, and sleep-related quality of life scores were similar between groups. One-month ESS and FOSQ scores were improved in the group empirically treated with auto-titrating CPAP. ESS scores improved in the first month by a mean of -3.2 (confidence interval -1.6 to -4.8, p life in a cohort of patients awaiting polysomnography who had a high pretest probability of having OSA. Additional studies are needed to evaluate the applicability of empiric treatment to other populations.

Differential Binding Models for Direct and Reverse Isothermal Titration Calorimetry.

Science.gov (United States)

Herrera, Isaac; Winnik, Mitchell A

2016-03-10

Isothermal titration calorimetry (ITC) is a technique to measure the stoichiometry and thermodynamics from binding experiments. Identifying an appropriate mathematical model to evaluate titration curves of receptors with multiple sites is challenging, particularly when the stoichiometry or binding mechanism is not available. In a recent theoretical study, we presented a differential binding model (DBM) to study calorimetry titrations independently of the interaction among the binding sites (Herrera, I.; Winnik, M. A. J. Phys. Chem. B 2013, 117, 8659-8672). Here, we build upon our DBM and show its practical application to evaluate calorimetry titrations of receptors with multiple sites independently of the titration direction. Specifically, we present a set of ordinary differential equations (ODEs) with the general form d[S]/dV that can be integrated numerically to calculate the equilibrium concentrations of free and bound species S at every injection step and, subsequently, to evaluate the volume-normalized heat signal (δQ(V) = δq/dV) of direct and reverse calorimetry titrations. Additionally, we identify factors that influence the shape of the titration curve and can be used to optimize the initial concentrations of titrant and analyte. We demonstrate the flexibility of our updated DBM by applying these differentials and a global regression analysis to direct and reverse calorimetric titrations of gadolinium ions with multidentate ligands of increasing denticity, namely, diglycolic acid (DGA), citric acid (CIT), and nitrilotriacetic acid (NTA), and use statistical tests to validate the stoichiometries for the metal-ligand pairs studied.

Simple and Automated Coulometric Titration of Acid Using Nonisolated Electrodes

Science.gov (United States)

Kuntzleman, Thomas S.; Kenney, Joshua B.; Hasbrouck, Scott; Collins, Michael J.; Amend, John R.

2011-01-01

Coulometric titrations involve the quantification of analyte by measurements of current and time. In most coulometric titrations, the anode and cathode are placed in isolated cells that are connected by a salt bridge. By contrast, the experiments described here involve coulometric titrations (of acidic protons in solution) using a silver anode and…

A Closer Look at Acid-Base Olfactory Titrations

Science.gov (United States)

Neppel, Kerry; Oliver-Hoyo, Maria T.; Queen, Connie; Reed, Nicole

2005-01-01

Olfactory titrations using raw onions and eugenol as acid-base indicators are reported. An in-depth investigation on olfactory titrations is presented to include requirements for potential olfactory indicators and protocols for using garlic, onions, and vanillin as acid-base olfactory indicators are tested.

Spectrophotometric titration of sulfates in the presence of zirconium

International Nuclear Information System (INIS)

Kuznetsov, V.V.; Kotova, S.S.; Molokanova, L.G.; Chekmarev, A.M.; Yagodin, G.A.

1978-01-01

The procedure has been proposed for express determination of sulphate ions in the presence of zirconium by spectrophotometric titration with the use of barium chloride and nitrochromazo as an indicator. The procedure is based on bonding zirconium into a more stable complex with EDTA (ethylenediaminotetraacetic acid). The presence of excess of EDTA and zirconium (4) complexonate in the solution being titrated does not affect the titration curve shape and the character of break on the curve in the equivalence point. A complete demasking of SO 4 2- is observed in the case of 1O-fold excess of EDTA with respect to zirconium (4). Statistic evaluation of the method has shown that the results of titration can be distorted by chance errors only

Green chemistry volumetric titration kit for pharmaceutical formulations: Econoburette

Directory of Open Access Journals (Sweden)

Man Singh

2009-08-01

Full Text Available Stopcock SC and Spring Sp models of Econoburette (Calibrated, RTC (NR, Ministry of Small Scale Industries, Government of India, developed for semimicro volumetric titration of pharmaceutical formulations are reported. These are economized and risk free titration where pipette is replaced by an inbuilt pipette and conical flask by inbuilt bulb. A step of pipetting of stock solution by mouth is deleted. It is used to allow solution exposure to user’s body. This risk is removed and even volatile and toxic solutions are titrated with full proof safety. Econoburette minimizes use of materials and time by 90 % and prevent discharge of polluting effluent to environment. Few acid and base samples are titrated and an analysis of experimental expenditure is described in the papers.

New applications of corrosion measurements by titration (CMT)

DEFF Research Database (Denmark)

Bech-Nielsen, Gregers

1998-01-01

. It is shown that when aluminium dissolves in alkali, CMT measurements can also be applied, but in this case requiring titration with alkali. Titration with alkali is also required in a special situation, where corrosion of nickel in an acid solution and subsequent formation of a nickel complex results...

The Potentiometric Titration of Filtrates from the Bachmann Process

Science.gov (United States)

1942-06-23

SCIENTIFIC RESEARCH AND DEVELOP11ENT The Potentiometric Titration of Filtrates from the Bachmann Process (OD-12) by F. C. Whitmore OSRD No. 654... Potentiometric Titration of Synthetic Mixtures. A? Nitric Acid-Acetic Acid. A sample of 60 ml. glacial acetic acid war diluted to 200 ml. with distilled...i4flinflr?fj3 TADLE 1 CO) |S?lDBnTl» POTENTIOMETRIC TITRATION OF SYNTHETIC t’.IXTURES WITH CONCENTRATED AJKDNIUM HYDROXIDE A; unonium HNO-j- AcOfi Ky

Comparison of VFA titration procedures used for monitoring the biogas process.

Science.gov (United States)

Lützhøft, Hans-Christian Holten; Boe, Kanokwan; Fang, Cheng; Angelidaki, Irini

2014-05-01

Titrimetric determination of volatile fatty acids (VFAs) contents is a common way to monitor a biogas process. However, digested manure from co-digestion biogas plants has a complex matrix with high concentrations of interfering components, resulting in varying results when using different titration procedures. Currently, no standardized procedure is used and it is therefore difficult to compare the performance among plants. The aim of this study was to evaluate four titration procedures (for determination of VFA-levels of digested manure samples) and compare results with gas chromatographic (GC) analysis. Two of the procedures are commonly used in biogas plants and two are discussed in literature. The results showed that the optimal titration results were obtained when 40 mL of four times diluted digested manure was gently stirred (200 rpm). Results from samples with different VFA concentrations (1-11 g/L) showed linear correlation between titration results and GC measurements. However, determination of VFA by titration generally overestimated the VFA contents compared with GC measurements when samples had low VFA concentrations, i.e. around 1 g/L. The accuracy of titration increased when samples had high VFA concentrations, i.e. around 5 g/L. It was further found that the studied ionisable interfering components had lowest effect on titration when the sample had high VFA concentration. In contrast, bicarbonate, phosphate and lactate had significant effect on titration accuracy at low VFA concentration. An extended 5-point titration procedure with pH correction was best to handle interferences from bicarbonate, phosphate and lactate at low VFA concentrations. Contrary, the simplest titration procedure with only two pH end-points showed the highest accuracy among all titration procedures at high VFA concentrations. All in all, if the composition of the digested manure sample is not known, the procedure with only two pH end-points should be the procedure of

A novel approach for high precision rapid potentiometric titrations: application to hydrazine assay.

Science.gov (United States)

Sahoo, P; Malathi, N; Ananthanarayanan, R; Praveen, K; Murali, N

2011-11-01

We propose a high precision rapid personal computer (PC) based potentiometric titration technique using a specially designed mini-cell to carry out redox titrations for assay of chemicals in quality control laboratories attached to industrial, R&D, and nuclear establishments. Using this technique a few microlitre of sample (50-100 μl) in a total volume of ~2 ml solution can be titrated and the waste generated after titration is extremely low comparing to that obtained from the conventional titration technique. The entire titration including online data acquisition followed by immediate offline analysis of data to get information about concentration of unknown sample is completed within a couple of minutes (about 2 min). This facility has been created using a new class of sensors, viz., pulsating sensors developed in-house. The basic concept in designing such instrument and the salient features of the titration device are presented in this paper. The performance of the titration facility was examined by conducting some of the high resolution redox titrations using dilute solutions--hydrazine against KIO(3) in HCl medium, Fe(II) against Ce(IV) and uranium using Davies-Gray method. The precision of titrations using this innovative approach lies between 0.048% and 1.0% relative standard deviation in different redox titrations. With the evolution of this rapid PC based titrator it was possible to develop a simple but high precision potentiometric titration technique for quick determination of hydrazine in nuclear fuel dissolver solution in the context of reprocessing of spent nuclear fuel in fast breeder reactors. © 2011 American Institute of Physics

Coulometric titration of niobium in 1F sulfuric acid

International Nuclear Information System (INIS)

Pannu, S.S.

1975-01-01

A coulometric titration at constant current has been devised for Nb in 1F sulfuric acid. The titration was based on the oxidation of Nb(III) to Nb(V) by Fe(III) electrogenerated at a graphite anode. Both potentiometric and amperometric end points were used. The Nb(V) was prior reduced at a mercury cathode by exhaustive electrolysis at a current density of 15 ma/mc 2 for at least 10 hr. Ta,V,Ti and a working platinum anode interfered, but the separation of the potentials of Nb(V)/Nb(III) and Ti(IV)/Ti(III) permitted the titration of first Nb and then Ti. The average error for the titration of 0.30 to 13.00 mg of niobium in 100 ml of 1F sulfuric acid was + 0.57%. (author)

Patient-led versus physician-led titration of insulin glargine in patients with uncontrolled type 2 diabetes: a randomized multinational ATLAS study.

Science.gov (United States)

Garg, Satish K; Admane, Karim; Freemantle, Nick; Odawara, Masato; Pan, Chang-Yu; Misra, Anoop; Jarek-Martynowa, Iwona R; Abbas-Raza, Syed; Mirasol, Roberto C; Perfetti, Riccardo

2015-02-01

Self-adjustment of insulin dose is commonly practiced in Western patients with type 2 diabetes but is usually not performed in Asian patients. This multinational, 24-week, randomized study compared patient-led with physician-led titration of once-daily insulin glargine in Asian patients with uncontrolled type 2 diabetes who were on 2 oral glucose-lowering agents. Patient-led (n = 275) or physician-led (n = 277) subjects followed the same dose-titration algorithm guided by self-monitored fasting blood glucose (FBG; target, 110 mg/dL [6.1 mmol/L]). The primary endpoint was change in mean glycated hemoglobin (HbA1c) at week 24 in the patient-led versus physician-led titration groups. Patient-led titration resulted in a significantly higher drop in HbA1c value at 24 weeks when compared with physician-led titration (-1.40% vs. -1.25%; mean difference, -0.15; 95% confidence interval, -0.29 to 0.00; P = .043). Mean decrease in FBG was greatest in the patient-led group (-2.85 mmol/L vs. -2.48 mmol/L; P = .001). The improvements in HbA1c and FBG were consistent across countries, with similar improvements in treatment satisfaction in both groups. Mean daily insulin dose was higher in the patient-led group (28.9 units vs. 22.2 units; Ptitration achieved near-target blood glucose levels in Asian patients with uncontrolled type 2 diabetes who were on 2 oral glucose-lowering drugs, demonstrating that Asian patients can self-uptitrate insulin dose effectively when guided.

Acid-base titrations by stepwise addition of equal volumes of titrant with special reference to automatic titrations-III Presentation of a fully automatic titration apparatus and of results supporting the theories given in the preceding parts.

Science.gov (United States)

Pehrsson, L; Ingman, F

1977-02-01

This paper forms Part III of a series in which the first two parts describe methods for evaluating titrations performed by stepwise addition of equal volumes of titrant. The great advantage of these methods is that they do not require an accurate calibration of the electrode system. This property makes the methods very suitable for routine work. e.g., in automatic analysis. An apparatus for performing such titrations automatically is presented. Further, results of titrations of monoprotic acids, a diprotic acid, an ampholyte, a mixture of an acid with its conjugate base, and mixtures of two acids with a small difference between the stability constants are given. Most of these titrations cannot be evaluated by the Gran or Hofstee methods but yield results having errors of the order of 0.1% if the methods proposed in Parts I and II of this series are employed. The advantages of the method of stepwise addition of equal volumes of titrant combined with the proposed evaluation methods, in comparison with common methods such as titration to a preset pH, are that all the data are used in the evaluation, permitting a statistical treatment and giving better possibilities for tracing systematic errors.

Feasibility and Association of Neurohumoral Blocker Up-titration After Cardiac Resynchronization Therapy.

Science.gov (United States)

Martens, Pieter; Verbrugge, Frederik H; Nijst, Petra; Bertrand, Philippe B; Dupont, Matthias; Tang, Wilson H; Mullens, Wilfried

2017-08-01

Cardiac resynchronization therapy (CRT) improves mortality and morbidity on top of optimal medical therapy in heart failure with reduced ejection fraction (HFrEF). This study aimed to elucidate the association between neurohumoral blocker up-titration after CRT implantation and clinical outcomes. Doses of angiotensin-converting enzyme inhibitors (ACE-Is), angiotensin receptor blockers (ARBs), and beta-blockers were retrospectively evaluated in 650 consecutive CRT patients implanted from October 2008 to August 2015 and followed in a tertiary multidisciplinary CRT clinic. All 650 CRT patients were on a maximal tolerable dose of ACE-I/ARB and beta-blocker at the time of CRT implantation. However, further up-titration was successful in 45.4% for ACE-I/ARB and in 56.8% for beta-blocker after CRT-implantation. During a mean follow-up of 37 ± 22 months, a total of 139 events occurred for the combined end point of heart failure admission and all-cause mortality. Successful, versus unsuccessful, up-titration was associated with adjusted hazard ratios of 0.537 (95% confidence interval 0.316-0.913; P = .022) for ACE-I/ARB and 0.633 (0.406-0.988; P = .044) for beta-blocker on the combined end point heart failure admission and all-cause mortality. Patients in the up-titration group exhibited a similar risk for death or heart failure admission as patients treated with the maximal dose (ACE-I/ARB: P = .133; beta-blockers: P = .709). After CRT, a majority of patients are capable of tolerating higher dosages of neurohumoral blockers. Up-titration of neurohumoral blockers after CRT implantation is associated with improved clinical outcomes, similarly to patients treated with the guideline-recommended target dose at the time of CRT implantation. Copyright © 2017 Elsevier Inc. All rights reserved.

Colloid Titration--A Rapid Method for the Determination of Charged Colloid.

Science.gov (United States)

Ueno, Keihei; Kina, Ken'yu

1985-01-01

"Colloid titration" is a volumetric method for determining charged polyelectrolytes in aqueous solutions. The principle of colloid titration, reagents used in the procedure, methods of endpoint detection, preparation of reagent solutions, general procedure used, results obtained, and pH profile of colloid titration are considered. (JN)

Effects of positive end-expiratory pressure titration and recruitment maneuver on lung inflammation and hyperinflation in experimental acid aspiration-induced lung injury.

Science.gov (United States)

Ambrosio, Aline M; Luo, Rubin; Fantoni, Denise T; Gutierres, Claudia; Lu, Qin; Gu, Wen-Jie; Otsuki, Denise A; Malbouisson, Luiz M S; Auler, Jose O C; Rouby, Jean-Jacques

2012-12-01

In acute lung injury positive end-expiratory pressure (PEEP) and recruitment maneuver are proposed to optimize arterial oxygenation. The aim of the study was to evaluate the impact of such a strategy on lung histological inflammation and hyperinflation in pigs with acid aspiration-induced lung injury. Forty-seven pigs were randomly allocated in seven groups: (1) controls spontaneously breathing; (2) without lung injury, PEEP 5 cm H2O; (3) without lung injury, PEEP titration; (4) without lung injury, PEEP titration + recruitment maneuver; (5) with lung injury, PEEP 5 cm H2O; (6) with lung injury, PEEP titration; and (7) with lung injury, PEEP titration + recruitment maneuver. Acute lung injury was induced by intratracheal instillation of hydrochloric acid. PEEP titration was performed by incremental and decremental PEEP from 5 to 20 cm H2O for optimizing arterial oxygenation. Three recruitment maneuvers (pressure of 40 cm H2O maintained for 20 s) were applied to the assigned groups at each PEEP level. Proportion of lung inflammation, hemorrhage, edema, and alveolar wall disruption were recorded on each histological field. Mean alveolar area was measured in the aerated lung regions. Acid aspiration increased mean alveolar area and produced alveolar wall disruption, lung edema, alveolar hemorrhage, and lung inflammation. PEEP titration significantly improved arterial oxygenation but simultaneously increased lung inflammation in juxta-diaphragmatic lung regions. Recruitment maneuver during PEEP titration did not induce additional increase in lung inflammation and alveolar hyperinflation. In a porcine model of acid aspiration-induced lung injury, PEEP titration aimed at optimizing arterial oxygenation, substantially increased lung inflammation. Recruitment maneuvers further improved arterial oxygenation without additional effects on inflammation and hyperinflation.

Characterization of pH titration shifts for all the nonlabile proton resonances in a protein by two-dimensional NMR: The case of mouse epidermal growth factor

International Nuclear Information System (INIS)

Kohda, Daisuke; Sawada, Toshie; Inagaki, Fuyuhiko

1991-01-01

The pH titration shifts for all the nonlabile proton resonances in a 53-residue protein (mouse epidermal growth factor) were measured in the p 2 H range 1.5-9 with two-dimensional (2D) 1 H NMR. The 2D NMR pH titration experiment made it possible to determine the pK values for all the ionizable group which were titrated in the pH range 1.5-9 in the protein. The pK values of the nine ionizable groups (α-amino group, four Asp, two Glu, one His, and α-carboxyl group) were found to be near their normal values. The 2D titration experiment also provided a detailed description of the pH-dependent behavior of the proton chemical shifts and enabled us to characterize the pH-dependent changes of protein conformation. Analysis of the pH-dependent shifts of ca. 200 proton resonances offered evidence of conformational changes in slightly basic pH solution: The deprotonation of the N-terminal α-amino group induced a widespread conformational change over the β-sheet structure in the protein, while the effects of deprotonation of the His22 imidazole group were relatively localized. The authors found that the 2D NMR pH titration experiment is a powerful tool for investigating the structural and dynamic properties of proteins

Potentiometric titration curves of aluminium salt solutions and its ...

African Journals Online (AJOL)

Potentiometric titration curves of aluminium salt solutions and its species conversion ... of aluminium salt solutions under the moderate slow rate of base injection. ... silicate radical, and organic acid radical on the titration curves and its critical ...

Computer Aided Flowsheet Design using Group Contribution Methods

DEFF Research Database (Denmark)

Bommareddy, Susilpa; Eden, Mario R.; Gani, Rafiqul

2011-01-01

In this paper, a systematic group contribution based framework is presented for synthesis of process flowsheets from a given set of input and output specifications. Analogous to the group contribution methods developed for molecular design, the framework employs process groups to represent...... information of each flowsheet to minimize the computational load and information storage. The design variables for the selected flowsheet(s) are identified through a reverse simulation approach and are used as initial estimates for rigorous simulation to verify the feasibility and performance of the design....

Effectiveness of a management program for outpatient clinic or remote titration of beta-blockers in CRT patients: The RESTORE study.

Science.gov (United States)

D'Onofrio, Antonio; Palmisano, Pietro; Rapacciuolo, Antonio; Ammendola, Ernesto; Calò, Leonardo; Ruocco, Antonio; Bianchi, Valter; Maresca, Fabio; Del Giorno, Giuseppe; Martino, Annamaria; Mauro, Ciro; Campari, Monica; Valsecchi, Sergio; Accogli, Michele

2017-06-01

Many patients fail to receive β-blockers before cardiac resynchronization therapy defibrillator (CRT-D) implantation, or receive them at a suboptimal dose, and require optimization after implantation. We assessed the effectiveness of a structured program for β-blocker titration in CRT-D patients followed up by means of conventional in-clinic visits or remote monitoring. 130 patients undergoing CRT implantation and treated according to the standard practice of the centers were included as a control group. A second group of 124 CRT-D candidates (Study Group) underwent up-titration visits every 2weeks after implantation (target dose: 10mg/day of bisoprolol or 50mg/day of carvedilol). In the Study Group, remote monitoring was undertaken in 66 patients, who received additional equipment for daily transmission of weight and blood pressure data, and scheduled titration telephone calls. In the Control Group, the maximal dose of β-blockers was being administered to 12 (9%) patients on implantation and 21 (16%) on 6-month follow-up examination (p>0.05). In the Study Group, 25 (20%) patients were receiving the maximal dose of β-blockers on implantation and 72 (58%) on follow-up examination (ptitration (versus 38% of patients followed up conventionally, ptitration increased the number of patients reaching the target dose and improved the response to the therapy. The use of remote monitoring and daily transfer of weight and blood pressure data facilitated β-blocker titration. URL: http://clinicaltrials.gov/ Identifier: NCT02173028. Copyright © 2017. Published by Elsevier B.V.

A new sensor for thermometric titrations.

Science.gov (United States)

Najib, Fadhil M; Zewar, Sardir; Abdulla, Ahmad M

2007-01-15

A new thermometric sensor, which is a transistor (OC71), has been introduced to follow thermometric titrations successfully to clear end points. The sensor was suitable in both normal and differential modes of titration. It is possible to titrate down to 1.32micromol of HCl and 26.4micromol of H(3)BO(3)in a final 20ml solution with accuracy and precision of 1%, 2.2% and 1.4%, 2.2%, respectively. The sensor, in association with a pH glass electrode, was used for the determination of pK values of some well established weak acids such as, acetic acid (4.77), phosphoric acid (pK(1)=2.18, pK(2)=7.20 and pK(3)=12.32) as well as for a very weak acid of uncertain pK values H(3)BO(3) (pK(1)=9.20, pK(2)=12.7 and pK(3)=13.80). The sensor was also examined for kinetic catalytic determination of iron(III) in water, milk and pharmaceuticals.

The fluorimetric titration of zirconium in the ppm-range

International Nuclear Information System (INIS)

Linden, W.E. von der; Boef, G. den; Ozinga, W.

1976-01-01

A fluorimetric titration of zirconium(IV) with EDTA is proposed. The fluorescence intensity of the zirconium-morin complex is used to indicate the end-point. More than twenty other cations were investigated and it was found that they did not interfere, neither did common anions. Mercury(II) can only be tolerated in amount not exceeding that of zirconium. Bismuth(III) interferes and hafnium(IV0 is titrated together with zirconium. The relative standard deviation of the titration of 10ml of a solution containing 1 ppm of zirconium does not exceed 1.5%

Potentiometric titrations of molybdenum and vanadium in aqueous and mixed so lvents

International Nuclear Information System (INIS)

Das, S.K.; Dhaneshwar, R.G.

1990-01-01

Potentiometric titration method was developed for molybdenum, employing different electrode systems. Molybdenum(VI) is reduced to molybdenum(V) by ferrous solution in presence of phosphoric acid and then titrated with potassium dichromate. It was found that ferrous concentration should be five times more than molybdenum and phosphoric acid should be 1.0 ml for 0.1N titration and 0.5 ml for lower concentration titrations. The method is also applicable to vanadium titrations. Employing Au/SCE and Pt/SCE systems, it was observed that generally curve heights obtained for platinum electrode are higher than those for gold electrode. Also for both the electrode systems, the curve heights for vanadium titrations were found to be more than those for molybdenum. Lower limits of titrations for Au/SCE system are 0.01N for molybdenum and 0.0001N for vanadium, whereas for Pt/SCE system, the lower limits obtained were 0.01N for both molybdenum and vanadium titrations. In order to improve the sensitivities of the method, the bimetallic electrode systems Au/Pt and Pt/Au were employed. Au/Pt system was found to give better results than Pt/Au systems. Addition of organic solvent was found to have beneficial effects for titrations of 0.001N and below. Methanol was found to be a better solvent than ethanol. Molybdenum titrations, at 0.0001N level could be performed in methanol with Au/Pt system, which is to b e generally preferred than Pt/Au system. (author). 7 refs., 3 tabs

Analysis of the Purity of Cetrimide by Titrations

DEFF Research Database (Denmark)

Andersen, Jens Enevold Thaulov; Rasmussen, Claus/Dallerup; Nielsen, Hans/Boye

2006-01-01

. Titration by perchloric acid showed a 99.69 ± 0.05 % purity of cetrimide and titration by silver nitrate showed a 99.85% ± 0.05 % purity while the traditional assay method predicted a purity of only 97.1 ± 0.4. It was found that the discrepancy could be identified as differences in selectivity during...

Thermometric titrations of amines with nitrosyl perchlorate in acetonitrile solvent.

Science.gov (United States)

Gündüz, T; Kiliç, E; Cakirer, O

1996-05-01

Thirteen aliphatic and four aromatic amines, namely diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-butylamine, isopropylamine, di-isopropylamine, n-butylamine, di-n-butylamine, tri-n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, aniline, N,N-dimethylaniline, 2-nitroaniline and 4-nitroaniline were titrated thermometrically with nitrosyl perchlorate in acetonitrile solvent. All the aliphatic amines gave very well-shaped thermometric titration curves. The calculated recovery values of the amines were very good. In comparison, the aromatic amines, aniline and N,N-dimethylaniline gave rather well-shaped titration curves, but the recovery values were fairly low. 2-Nitro- and 4-nitro anilines gave no thermometric response at all. The heats of reaction of the amines with nitrosyl perchlorate are rather high. However, the average heat of reaction of the aromatic amines is approximately two-thirds that of the average heat of the aliphatic amines. To support this method all the amines were also titrated potentiometrically and very similar results to those obtained with the thermometric method are seen. The nitrosyl ion is a Lewis acid, strong enough to titrate quantitatively aliphatic amines in acetonitrile solvent, but not strong enough to titrate aromatic amines at the required level in the same solvent.

Gran method for end point anticipation in monosegmented flow titration

Directory of Open Access Journals (Sweden)

Aquino Emerson V

2004-01-01

Full Text Available An automatic potentiometric monosegmented flow titration procedure based on Gran linearisation approach has been developed. The controlling program can estimate the end point of the titration after the addition of three or four aliquots of titrant. Alternatively, the end point can be determined by the second derivative procedure. In this case, additional volumes of titrant are added until the vicinity of the end point and three points before and after the stoichiometric point are used for end point calculation. The performance of the system was assessed by the determination of chloride in isotonic beverages and parenteral solutions. The system employs a tubular Ag2S/AgCl indicator electrode. A typical titration, performed according to the IUPAC definition, requires only 60 mL of sample and about the same volume of titrant (AgNO3 solution. A complete titration can be carried out in 1 - 5 min. The accuracy and precision (relative standard deviation of ten replicates are 2% and 1% for the Gran and 1% and 0.5% for the Gran/derivative end point determination procedures, respectively. The proposed system reduces the time to perform a titration, ensuring low sample and reagent consumption, and full automatic sampling and titrant addition in a calibration-free titration protocol.

A randomised controlled trial evaluating IGF1 titration in contrast to current GH dosing strategies in children born small for gestational age: the North European Small-for-Gestational-Age Study.

Science.gov (United States)

Jensen, Rikke Beck; Thankamony, Ajay; O'Connell, Susan M; Kirk, Jeremy; Donaldson, Malcolm; Ivarsson, Sten-A; Söder, Olle; Roche, Edna; Hoey, Hilary; Dunger, David B; Juul, Anders

2014-10-01

Short children born small for gestational age (SGA) are treated with a GH dose based on body size, but treatment may lead to high levels of IGF1. The objective was to evaluate IGF1 titration of GH dose in contrast to current dosing strategies. In the North European Small-for-Gestational-Age Study (NESGAS), 92 short pre-pubertal children born SGA were randomised after 1 year of high-dose GH treatment (67 μg/kg per day) to three different regimens: high dose (67 μg/kg per day), low dose (35 μg/kg per day) or IGF1 titration. The average dose during the second year of the randomised trial did not differ between the IGF1 titration group (38 μg/kg per day, s.d. 0.019) and the low-dose group (35 μg/kg per day, s.d. 0.002; P=0.46), but there was a wide variation in the IGF1 titration group (range 10-80 μg/kg per day). The IGF1 titration group had significantly lower height gain (0.17 SDS, s.d. 0.18) during the second year of the randomised trial compared with the high-dose group (0.46 SDS, s.d. 0.25), but not significantly lower than the low-dose group (0.23 SDS, s.d. 0.15; P=0.17). The IGF1 titration group had lower IGF1 levels after 2 years of the trial (mean 1.16, s.d. 1.24) compared with both the low-dose (mean 1.76, s.d. 1.48) and the high-dose (mean 2.97, s.d. 1.63) groups. IGF1 titration of GH dose in SGA children proved less effective than current dosing strategies. IGF1 titration resulted in physiological IGF1 levels with a wide range of GH dose and a poorer growth response, which indicates the role of IGF1 resistance and highlights the heterogeneity of short SGA children. © 2014 European Society of Endocrinology.

Thermometric Titration for Rapid Determination of Trace Water in Jet Fuel

Directory of Open Access Journals (Sweden)

Jian-Qiang Hu

2017-01-01

Full Text Available Water content in jet fuels is detected by thermometric titration (TMT, and the optimal detected system is 2,2-dimethoxypropane as titrant, cyclohexane and isopropanol as titration solvents, and methanesulfonic acid as catalyst in this method. The amounts of oil, concentration and delivery rate of titrant, volumes, and the reliability and accuracy of thermometric titration were emphasized. The results show that the accuracy, validity, and reliability of TMT are excellent by different indicated spiked water contents. The obtained results between TMT and Karl Fischer titration have been proven to be in accord. But, the duration of titration merely spends 3–5 min in the whole process, greatly shortening the detected time. Therefore, rapid and accurate determination of trace water in a jet fuel can be realized by TMT.

Filtrates & Residues: Olfactory Titration.

Science.gov (United States)

Wood, John T.; Eddy, Roberta M.

1996-01-01

Presents an experiment that uses a unique acid-base indicator--the odor of raw onion--to indicate the end point of the titration of sodium hydroxide with hydrochloric acid. Allows the student to detect the completion of the neutralization reaction by olfaction rather than sight. (JRH)

Free Software Development. 3. Numerical Description of Soft Acid with Soft Base Titration

Directory of Open Access Journals (Sweden)

Lorentz JÄNTSCHI

2002-12-01

Full Text Available The analytical methods of qualitative and quantitative determination of ions in solutions are very flexible to automation. The present work is focus on modeling the process of titration and presents a numerical simulation of acid-base titration. A PHP program to compute all iterations in titration process that solves a 3th rank equation to find value of pH for was built and is available through http internet protocol at the address: http://vl.academicdirect.org/molecular_dynamics/ab_titrations/v1.1/ The method allows expressing the value of pH in any point of titration process and permits to observe the equivalence point of titration.

Ionization behavior of polyphosphoinositides determined via the preparation of pH titration curves using solid-state 31P NMR.

Science.gov (United States)

Graber, Zachary T; Kooijman, Edgar E

2013-01-01

Detailed knowledge of the degree of ionization of lipid titratable groups is important for the evaluation of protein-lipid and lipid-lipid interactions. The degree of ionization is commonly evaluated by acid-base titration, but for lipids localized in a multicomponent membrane interface this is not a suitable technique. For phosphomonoester-containing lipids such as the polyphosphoinositides, phosphatidic acid, and ceramide-1-phosphate, this is more conveniently accomplished by (31)P NMR. Here, we describe a solid-state (31)P NMR procedure to construct pH titration curves to determine the degree of ionization of phosphomonoester groups in polyphosphoinositides. This procedure can also be used, with suitable sample preparation conditions, for other important signaling lipids. Access to a solid-state, i.e., magic angle spinning, capable NMR spectrometer is assumed. The procedures described here are valid for a Bruker instrument, but can be adapted for other spectrometers as needed.

Amperometric, Bipotentiometric, and Coulometric Titration.

Science.gov (United States)

Stock, John T.

1980-01-01

Discusses recent review articles in various kinds of titration. Also discusses new research in apparatus and methodology, acid-base reactions, precipitation and complexing reactions, oxidation-reduction reactions, and nomenclature. Cites 338 references. (CS)

Switching From Age-Based Stimulus Dosing to Dose Titration Protocols in Electroconvulsive Therapy: Empirical Evidence for Better Patient Outcomes With Lower Peak and Cumulative Energy Doses.

Science.gov (United States)

O'Neill-Kerr, Alex; Yassin, Anhar; Rogers, Stephen; Cornish, Janie

2017-09-01

The aim of this study was to test the proposition that adoption of a dose titration protocol may be associated with better patient outcomes, at lower treatment dose, and with comparable cumulative dose to that in patients treated using an age-based stimulus dosing protocol. This was an analysis of data assembled from archived records and based on cohorts of patients treated respectively on an age-based stimulus dosing protocol and on a dose titration protocol in the National Health Service in England. We demonstrated a significantly better response in the patient cohort treated with dose titration than with age-based stimulus dosing. Peak doses were less and the total cumulative dose was less in the dose titration group than in the age-based stimulus dosing group. Our findings are consistent with superior outcomes in patients treated using a dose titration protocol when compared with age-based stimulus dosing in a similar cohort of patients.

Digital movie-based on automatic titrations.

Science.gov (United States)

Lima, Ricardo Alexandre C; Almeida, Luciano F; Lyra, Wellington S; Siqueira, Lucas A; Gaião, Edvaldo N; Paiva Junior, Sérgio S L; Lima, Rafaela L F C

2016-01-15

This study proposes the use of digital movies (DMs) in a flow-batch analyzer (FBA) to perform automatic, fast and accurate titrations. The term used for this process is "Digital movie-based on automatic titrations" (DMB-AT). A webcam records the DM during the addition of the titrant to the mixing chamber (MC). While the DM is recorded, it is decompiled into frames ordered sequentially at a constant rate of 26 frames per second (FPS). The first frame is used as a reference to define the region of interest (ROI) of 28×13pixels and the R, G and B values, which are used to calculate the Hue (H) values for each frame. The Pearson's correlation coefficient (r) is calculated between the H values of the initial frame and each subsequent frame. The titration curves are plotted in real time using the r values and the opening time of the titrant valve. The end point is estimated by the second derivative method. A software written in C language manages all analytical steps and data treatment in real time. The feasibility of the method was attested by application in acid/base test samples and edible oils. Results were compared with classical titration and did not present statistically significant differences when the paired t-test at the 95% confidence level was applied. The proposed method is able to process about 117-128 samples per hour for the test and edible oil samples, respectively, and its precision was confirmed by overall relative standard deviation (RSD) values, always less than 1.0%. Copyright © 2015 Elsevier B.V. All rights reserved.

When acid-base titrations are carried out in unusual conditions

Directory of Open Access Journals (Sweden)

Domenico De Marco

2012-12-01

Full Text Available Uncommon aspects in acid-base titrations are presented, which occur in titrations between both mono- and/or poly-functional acid and bases but are rarely introduced in ordinary analytical chemistry courses.

Spasmodic dysphonia: a seven-year audit of dose titration and demographics in the Indian population.

Science.gov (United States)

Nerurkar, N K; Banu, T P

2014-07-01

This study aimed to evaluate the demographics of spasmodic dysphonia in the Indian population and to analyse the optimum dose titration of botulinum toxin type A in this group. A comparative analysis with international studies was also performed. The study involved a retrospective analysis and audit of botulinum toxin type A dose titration in spasmodic dysphonia patients who visited our voice clinic between January 2005 and January 2012. The average total therapeutic dose required for patients with adductor spasmodic dysphonia was 4.2 U per patient per vocal fold (total 8.4 U per patient), and for patients with abductor spasmodic dysphonia, it was 4.6 U per patient. Our audit revealed that 80 per cent of the spasmodic dysphonia patients were male, which contrasts dramatically with international studies, wherein around 80 per cent of spasmodic dysphonia patients were female. Our study also revealed a higher dose titration of botulinum toxin for the Indian spasmodic dysphonia population in both adductor and abductor spasmodic dysphonia cases.

Spectrophotometric titrations: Application to the determination of some elements in uranium solutions

International Nuclear Information System (INIS)

L'Her, M.

1967-01-01

The aim of this work is the application of spectrophotometric titrations to the analysis of uranium-containing solutions. We have been led to examine the general principles involved in these titrations, and we give a brief outline of these principles. In the first part we deal therefore with spectrophotometric titrations from a general point of view, examining their fundamental principle, their practical execution as well as the various possibilities of the method. The advantage of the titration are examined, in particular that of lending itself simultaneous determination of two species. The possibility of applying these spectrophotometric titrations to the analysis of uranium-containing solutions is the subject of the second part of this report: the dosage of a few species in uranium (VI) solutions is described. To this second part is added an experimental appendix consisting of a description of the apparatus, as well as of the operational techniques used for certain titrations, in particular those involving solutions containing uranium. (author) [fr

Prescribing and up-titration in recently hospitalized heart failure patients attending a disease management program.

Science.gov (United States)

Carroll, Robert; Mudge, Alison; Suna, Jessica; Denaro, Charles; Atherton, John

2016-08-01

Heart failure (HF) medications improve clinical outcomes, with optimal doses defined in clinical trials. Patient, provider and system barriers may limit achievement of optimal doses in real life settings, although disease management programs (HF-DMPs) can facilitate up-titration. Secondary analysis of a prospective cohort of 216 participants recently hospitalized with systolic HF, attending 5 HF-DMPs in Queensland, Australia. Medication history at baseline (6weeks after discharge) and 6months provided data to describe prescription rates, dosage and optimal titration of HF medications, and associations with patient and system factors were explored. At baseline, 94% were on an angiotensin converting enzyme inhibitor/angiotensin II receptor blocker (ACEI/ARB), 94% on a beta-blocker (BB) and 42% on a mineralocorticoid receptor antagonist (MRA). The proportion of participants on optimal doses of ACEI/ARB increased from 38% (baseline) to 52% (6months, p=0.001) and on optimal BB dose from 23% to 49% (ptitration were body mass index (BMI)titration were BMItitration in HF DMPs is influenced by patient, disease and service factors. Better understanding of barriers to effective up-titration in women, normal weight, and established HF patients may help provide targeted strategies for improving outcomes in these groups. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Group Contribution Method for Estimating Cetane and Octane Numbers

Energy Technology Data Exchange (ETDEWEB)

Kubic, William Louis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Process Modeling and Analysis Group

2016-07-28

Much of the research on advanced biofuels is devoted to the study of novel chemical pathways for converting nonfood biomass into liquid fuels that can be blended with existing transportation fuels. Many compounds under consideration are not found in the existing fuel supplies. Often, the physical properties needed to assess the viability of a potential biofuel are not available. The only reliable information available may be the molecular structure. Group contribution methods for estimating physical properties from molecular structure have been used for more than 60 years. The most common application is estimation of thermodynamic properties. More recently, group contribution methods have been developed for estimating rate dependent properties including cetane and octane numbers. Often, published group contribution methods are limited in terms of types of function groups and range of applicability. In this study, a new, broadly-applicable group contribution method based on an artificial neural network was developed to estimate cetane number research octane number, and motor octane numbers of hydrocarbons and oxygenated hydrocarbons. The new method is more accurate over a greater range molecular weights and structural complexity than existing group contribution methods for estimating cetane and octane numbers.

The Davies-Gray titration for the assay of uranium in nuclear materials: a performance study

International Nuclear Information System (INIS)

Bickel, M.

1997-01-01

An interlaboratory comparison in two phases was organized to assess the precision and accuracy concerning the assay of uranium in nuclear materials by the potentiometric titration method. This contribution presents the results of this exercise in terms of method performance. Variations to be expected between different laboratories and within a single laboratory are estimated. In general, the method proved again very reliable. (orig.)

Carbon dioxide titration method for soil respiration measurements

OpenAIRE

Martín Rubio, Luis

2017-01-01

This thesis was commissioned by Tampere University of Applied Sciences, which was interested in studying and developing a titration measurement method for soil respiration and biodegradability. Some experiments were carried out measuring soil respiration for testing the method and others adding some biodegradable material like polylactic acid compressed material and 100% biodegradable plastic bags to test its biodegradability and the possibility to measure it via titration. The thesi...

The Mobile Insulin Titration Intervention (MITI) for Insulin Glargine Titration in an Urban, Low-Income Population: Randomized Controlled Trial Protocol.

Science.gov (United States)

Levy, Natalie; Moynihan, Victoria; Nilo, Annielyn; Singer, Karyn; Bernik, Lidia S; Etiebet, Mary-Ann; Fang, Yixin; Cho, James; Natarajan, Sundar

2015-03-13

Patients on insulin glargine typically visit a clinician to obtain advice on how to adjust their insulin dose. These multiple clinic visits can be costly and time-consuming, particularly for low-income patients. It may be feasible to achieve insulin titration through text messages and phone calls with patients instead of face-to-face clinic visits. The objectives of this study are to (1) evaluate if the Mobile Insulin Titration Intervention (MITI) is clinically effective by helping patients reach their optimal dose of insulin glargine, (2) determine if the intervention is feasible within the setting and population, (3) assess patient satisfaction with the intervention, and (4) measure the costs associated with this intervention. This is a pilot study evaluating an approach to insulin titration using text messages and phone calls among patients with insulin-dependent type 2 diabetes in the outpatient medical clinic of Bellevue Hospital Center, a safety-net hospital in New York City. Patients will be randomized in a 1:1 ratio to either the MITI arm (texting/phone call intervention) or the usual-care arm (in-person clinic visits). Using a Web-based platform, weekday text messages will be sent to patients in the MITI arm, asking them to text back their fasting blood glucose values. In addition to daily reviews for alarm values, a clinician will rereview the texted values weekly, consult our physician-approved titration algorithm, and call the patients with advice on how to adjust their insulin dose. The primary outcome will be whether or not a patient reaches his/her optimal dose of insulin glargine within 12 weeks. Recruitment for this study occurred between June 2013 and December 2014. We are continuing to collect intervention and follow-up data from our patients who are currently enrolled. The results of our data analysis are expected to be available in 2015. This study explores the use of widely-available text messaging and voice technologies for insulin titration

Using Spectrophotometric Titrations To Characterize Humic Acid Reactivity at Environmental Concentrations

International Nuclear Information System (INIS)

Janot, N.; Benedetti, M. F.; Janot, N.; Reiller, P. E.; Korshin, G. V.

2010-01-01

Potentiometric titration is a common method to characterize dissolved organic matter (DOM) reactivity. Because of the sensitivity of pH electrodes, it is necessary to work with very high DOM (≥1 g/L) concentrations that are unrealistic compared to those found in natural waters (0. 1 to 100 mg/L). To obtain proton binding data for concentrations closer to environmental values, spectroscopic titration methodology is a viable alternative to traditional potentiometric titrations. Spectrophotometric titrations and UV visible spectra of a diluted solution of purified Aldrich humic acid (5 mg(DOC)/L) are used to estimate changes in proton binding moieties as function of pH and ionic strength after calculation of differential absorbance spectra variations. After electrostatic correction of spectrophotometric data, there is a linear operational correlation between spectrophotometric and potentiometric data which can be used as a transfer function between the two properties. Spectrophotometric titrations are then used to determine the changes of humic acid protonation after adsorption onto alpha-alumina. (authors)

Using Spectrophotometric Titrations To Characterize Humic Acid Reactivity at Environmental Concentrations

Energy Technology Data Exchange (ETDEWEB)

Janot, N.; Benedetti, M. F. [Univ Paris Diderot, Lab Geochim Eaux, UMR CNRS 7154, IPGP, F-75025 Paris 13 (France); Janot, N.; Reiller, P. E. [CE Saclay, CEA DEN DANS DPC SECR, Lab Speciat Radionucleides and Mol, F-91191 Gif Sur Yvette (France); Korshin, G. V. [Univ Washington, Dept Civil and Environm Engn, Seattle, WA 98195 (United States)

2010-07-01

Potentiometric titration is a common method to characterize dissolved organic matter (DOM) reactivity. Because of the sensitivity of pH electrodes, it is necessary to work with very high DOM ({>=}1 g/L) concentrations that are unrealistic compared to those found in natural waters (0. 1 to 100 mg/L). To obtain proton binding data for concentrations closer to environmental values, spectroscopic titration methodology is a viable alternative to traditional potentiometric titrations. Spectrophotometric titrations and UV visible spectra of a diluted solution of purified Aldrich humic acid (5 mg(DOC)/L) are used to estimate changes in proton binding moieties as function of pH and ionic strength after calculation of differential absorbance spectra variations. After electrostatic correction of spectrophotometric data, there is a linear operational correlation between spectrophotometric and potentiometric data which can be used as a transfer function between the two properties. Spectrophotometric titrations are then used to determine the changes of humic acid protonation after adsorption onto alpha-alumina. (authors)

Electroconvulsive therapy stimulus titration: Not all it seems.

Science.gov (United States)

Rosenman, Stephen J

2018-05-01

To examine the provenance and implications of seizure threshold titration in electroconvulsive therapy. Titration of seizure threshold has become a virtual standard for electroconvulsive therapy. It is justified as individualisation and optimisation of the balance between efficacy and unwanted effects. Present day threshold estimation is significantly different from the 1960 studies of Cronholm and Ottosson that are its usual justification. The present form of threshold estimation is unstable and too uncertain for valid optimisation or individualisation of dose. Threshold stimulation (lowest dose that produces a seizure) has proven therapeutically ineffective, and the multiples applied to threshold to attain efficacy have never been properly investigated or standardised. The therapeutic outcomes of threshold estimation (or its multiples) have not been separated from simple dose effects. Threshold estimation does not optimise dose due to its own uncertainties and the different short-term and long-term cognitive and memory effects. Potential harms of titration have not been examined. Seizure threshold titration in electroconvulsive therapy is not a proven technique of dose optimisation. It is widely held and practiced; its benefit and harmlessness assumed but unproven. It is a prematurely settled answer to an unsettled question that discourages further enquiry. It is an example of how practices, assumed scientific, enter medicine by obscure paths.

Graphical evaluation of complexometric titration curves.

Science.gov (United States)

Guinon, J L

1985-04-01

A graphical method, based on logarithmic concentration diagrams, for construction, without any calculations, of complexometric titration curves is examined. The titration curves obtained for different kinds of unidentate, bidentate and quadridentate ligands clearly show why only chelating ligands are usually used in titrimetric analysis. The method has also been applied to two practical cases where unidentate ligands are used: (a) the complexometric determination of mercury(II) with halides and (b) the determination of cyanide with silver, which involves both a complexation and a precipitation system; for this purpose construction of the diagrams for the HgCl(2)/HgCl(+)/Hg(2+) and Ag(CN)(2)(-)/AgCN/CN(-) systems is considered in detail.

Determination of uranium by direct titration with dipicolinic acid

International Nuclear Information System (INIS)

Baumann, E.W.

1984-01-01

Direct titration of uranium with dipicolinic acid, in the presence of Arsenazo I, is a simple, precise, and accurate method for uranium determination. The method is particularly attractive because it can be totally automated. Detecting the end point (color change from blue to pink) depends on the concentration range. For the Micro Method (1 to 20 ppM U in the solution titrated), the gradual color change is monitored spectrophotometrically. For the Macro Method (20 to 300 ppM), the end point is determined either visually or spectrophotometrically. The spectrophotometric end point is computed by fitting the titration curve. The relative standard deviation is +-1 to 3% for the Micro Method and +-0.3% for the Macro Method

Initial Evaluation of a Titration Appliance for Temporary Treatment of Obstructive Sleep Apnea.

Science.gov (United States)

Levendowski, Daniel J; Morgan, Todd; Westbrook, Philip

2012-01-01

Custom oral appliances that adjustably advance the mandible provide superior outcomes when treating patients with moderate or severe sleep apnea. Custom appliances, however, are expensive, must be fitted by a dentist, and the likelihood of successful outcomes are difficult to predict. An inexpensive trial appliance, if proven efficacious, might be used to predict custom appliance outcomes or to provide temporary therapeutic benefit. The aim of this initial study was to assess the treatment efficacy of a novel titration oral appliance with that of an optimized custom appliance. Seventeen patients, treated with a custom oral appliance for at least one year, successfully completed a three-night home sleep test. The baseline obstructive sleep apnea severity was established on Night 1 with seven patients exhibiting severe, six moderate and four mild apnea/hypopnea indexes. Patients were randomly assigned to wear their custom appliance or the titration appliance on Nights 2 and 3. Significant reductions in the mean overall and supine apnea indexes (p titration and custom appliances. The proportion of patients who exhibited at least a 50% reduction in the overall apnea index and supine apnea/hypopnea were similar for the titration and custom appliance (~60%). The custom appliance reduced the overall apnea/hypopnea index by 50% in a greater proportion of the patients compared to the titration appliance (77% vs. 53%). The titration appliance significantly reduced the degree of hypoxic exposure across sleep disordered breathing events overall (p titration appliance, but preferred the titration appliance to no therapy. The titration appliance may be useful in assessing oral appliance treatment efficacy. When set to 70% of maximum protrusion, the titration appliance may provide immediate, temporary therapeutic benefit.

Thermodynamic investigations of protein's behaviour with ionic liquids in aqueous medium studied by isothermal titration calorimetry.

Science.gov (United States)

Bharmoria, Pankaj; Kumar, Arvind

2016-05-01

While a number of reports appear on ionic liquids-proteins interactions, their thermodynamic behaviour using suitable technique like isothermal titration calorimetry is not systematically presented. Isothermal titration calorimetry (ITC) is a key technique which can directly measure the thermodynamic contribution of IL binding to protein, particularly the enthalpy, heat capacities and binding stoichiometry. Ionic liquids (ILs), owing to their unique and tunable physicochemical properties have been the central area of scientific research besides graphene in the last decade, and growing unabated. Their encounter with proteins in the biological system is inevitable considering their environmental discharge though most of them are recyclable for a number of cycles. In this article we will cover the thermodynamics of proteins upon interaction with ILs as osmolyte and surfactant. The up to date literature survey of IL-protein interactions using isothermal titration calorimetry will be discussed and parallel comparison with the results obtained for such studies with other techniques will be highlighted to demonstrate the accuracy of ITC technique. Net stability of proteins can be obtained from the difference in the free energy (ΔG) of the native (folded) and denatured (unfolded) state using the Gibbs-Helmholtz equation (ΔG=ΔH-TΔS). Isothermal titration calorimetry can directly measure the heat changes upon IL-protein interactions. Calculation of other thermodynamic parameters such as entropy, binding constant and free energy depends upon the proper fitting of the binding isotherms using various fitting models. Copyright © 2015 Elsevier B.V. All rights reserved.

Monitoring Acid–Base Titrations on Wax Printed Paper Microzones Using a Smartphone

Directory of Open Access Journals (Sweden)

Sandro A. Nogueira

2017-05-01

Full Text Available This study describes the use of a smartphone for monitoring acid–base titrations on wax printed paper microzones. An array of twelve microzones of 5 mm diameter each was wax printed on filter paper. The analytical performance of the proposed devices was explored with acid–base titrations examples, where jaboticaba peel extract was used as a natural pH indicator. The color intensity was captured using a smartphone and analyzed through a free App named Photometrix®. Before titrations, color intensity versus pH was calibrated to be used as a reference in titrations as (i strong acid versus strong base; (ii strong base versus strong acid; and (iii weak acid versus strong base. In all examples, images were obtained after the addition of each aliquot of titrant solutions. The obtained titration curves showed the same behavior as the conventional titration curves. After evaluating the feasibility of the proposed methodology, the concentration level of acetic acid was obtained in three vinegar samples. Although the obtained values ranged from 5% to 8% compared to the concentrations on the conventional method, the proposed methodology presented high analytical reliability. The calculated concentrations of acetic acid in three samples ranged from 3.87% to 3.93%, and the proposed methodology did not significantly differ from classic acid–base titration at a confidence level of 95%. The acid–base titration on paper-based devices is outstanding, since any titration can be completed within 5 min using 20 µL volumes. Besides, the use of a smartphone to capture images followed by analysis in a free app offers simplicity to all users. The proposed methodology arises as a new strand to be exploited in the diffusion of the analytical chemistry education field as well as an alternative for quantitative analysis with extremely simplified instrumentation.

Group Contribution Based Process Flowsheet Synthesis, Design and Modelling

DEFF Research Database (Denmark)

d'Anterroches, Loïc; Gani, Rafiqul

2005-01-01

In a group contribution method for pure component property prediction, a molecule is described as a set of groups linked together to form a molecular structure. In the same way, for flowsheet "property" prediction, a flowsheet can be described as a set of process-groups linked together to represent...... the flowsheet structure. Just as a functional group is a collection of atoms, a process-group is a collection of operations forming an "unit" operation or a set of "unit" operations. The link between the process-groups are the streams similar to the bonds that are attachments to atoms/groups. Each process-group...... provides a contribution to the "property" of the flowsheet, which can be performance in terms of energy consumption, thereby allowing a flowsheet "property" to be calculated, once it is described by the groups. Another feature of this approach is that the process-group attachments provide automatically...

Thermometric Titration for Rapid Determination of Trace Water in Jet Fuel

OpenAIRE

Hu, Jian-Qiang; Zhang, Jian-Jian; Yang, Shi-Zhao; Xin, Yong-Liang; Guo, Li; Yao, Ting

2017-01-01

Water content in jet fuels is detected by thermometric titration (TMT), and the optimal detected system is 2,2-dimethoxypropane as titrant, cyclohexane and isopropanol as titration solvents, and methanesulfonic acid as catalyst in this method. The amounts of oil, concentration and delivery rate of titrant, volumes, and the reliability and accuracy of thermometric titration were emphasized. The results show that the accuracy, validity, and reliability of TMT are excellent by different indicate...

The predictive value of drug-induced sleep endoscopy for CPAP titration in OSA patients.

Science.gov (United States)

Lan, Ming-Chin; Hsu, Yen-Bin; Lan, Ming-Ying; Huang, Yun-Chen; Kao, Ming-Chang; Huang, Tung-Tsun; Chiu, Tsan-Jen; Yang, Mei-Chen

2017-12-15

The aim of this study was to identify possible upper airway obstructions causing a higher continuous positive airway pressure (CPAP) titration level, utilizing drug-induced sleep endoscopy (DISE). A total of 76 patients with obstructive sleep apnea (OSA) underwent CPAP titration and DISE. DISE findings were recorded using the VOTE classification system. Polysomnographic (PSG) data, anthropometric variables, and patterns of airway collapse during DISE were analyzed with CPAP titration levels. A significant association was found between the CPAP titration level and BMI, oxygen desaturation index (ODI), apnea-hypopnea index (AHI), and neck circumference (NC) (P CPAP titration level (P CPAP titration level and any other collapse at the tongue base or epiglottis. By analyzing PSG data, anthropometric variables, and DISE results with CPAP titration levels, we can better understand possible mechanisms resulting in a higher CPAP titration level. We believe that the role of DISE can be expanded as a tool to identify the possible anatomical structures that may be corrected by oral appliance therapy or surgical intervention to improve CPAP compliance.

The determination of titratable acidity and total tannins in red wine

OpenAIRE

Rajković Miloš B.; Sredović Ivana D.

2009-01-01

Titration acidity and content of total tannins in mass-market red wines are analyzed in this paper. The content of total acids in wine, expressed through wine acid, was analyzed by potentiometric titration on 7.00 pH value. According to titratable acidity in analyzed wines, all wines (only) with analyzed parameters according to Regulations about wine quality. The analysis of differential potentiometric curves shows that these curves can give the answer to the question if non organic substance...

Potentiometric titration of molybdenum (6) with a cathode-polarized solid electrode

International Nuclear Information System (INIS)

Boeva, L.V.; Kimstach, V.A.; Bagdasarov, K.N.

1980-01-01

The possibility has been studied of using solid electrodes for potentiometric precipitation titration of molybdenum (6). A cathode-polarized electrode, electrochemically covered with a molybdenum blue layer, can be used as indicator electrode. The best results were obtained during deposition of molybdenum blue on a tungsten electrode. The mechanism of electrode work during titration has been investigated. A procedure has been developed of titration of molybdenum (6) in acid solutions using hydroxylamine N-aryl derivatives as titrants

Acid/base titrations of simulated PWR crevice environments

International Nuclear Information System (INIS)

Pang, J.; Macdonald, D.D.; Millett, P.J.

1993-01-01

The construction and operation of a titration system that is capable of exploring the acid/base properties of aqueous systems at temperatures solution is measured using YSZ sensors of the type Hg/HgO/ZrO 2 (Y 2 O 3 )/Solution in conjunction with a suitable reference electrode. The use of the system for measuring the pH of the titrated solutions (NaOH/H 2 SO 4 ) is discussed, and we show that the YSZ pH sensor is capable of consistent and precise pH measurements at elevated temperature (275-325 degrees C) and pressures (100-150 bars). However, the accuracy of the measured pH depends critically on the performance of the reference electrode. In the present work, we ensure the viability of the reference electrode. In the present work, we ensure the viability of the reference electrode by periodically calibrating it in situ using the pH sensor and a standard solution of known pH versus temperature characteristics. The titration data obtained in this study are compared with predictions from EPRI's MULTEQ code, and are found to be in satisfactory agreement in the alkaline pH region. Observed discrepancies in the acidic pH region between the two sets of data are attributed to corrosion of the alloys used to fabricate the titration system

Construction and use of an optical semi-automatic titrator employing the technique of reflectance photometry

International Nuclear Information System (INIS)

Hwang, Hoon

2001-01-01

An optical semi-automatic titrator was constructed employing the technique of the reflectance spectrometry and was tested for the determination of the end points of the acid-base, precipitation, and EDTA titrations. And since the current optical semi-automatic titrator built on the principle of the reflectance spectrometry could be successfully used even for the determination of the end of the end point in the precipitation titration where the solid particles are formed during the titration process, it was found to be feasible that a completely automated optical titrator would be designed and built based on the current findings

Evaluation of the performance of a metrohm titrator titrando-836 in potentiometric analysis of uranium for safeguards purposes

International Nuclear Information System (INIS)

Cristiano, Barbara Fernandes; Silva, Jose Wanderley S. da; Barros, Pedro Dionisio de; Araujo, Radier Mario S. de

2009-01-01

To achieve the requirements of the Brazilian State System of Accounting for and Control of Nuclear Materials - SSAC the Safeguards Laboratory of Brazilian Nuclear Energy Commission, LASAL, has been applying the 'Davies and Gray/NBL' method for Potentiometric determination of total uranium concentration in several forms of nuclear materials since 1984. To improve the accuracy and the repeatability the method uses as titrant, standard reference potassium dichromate NIST SRM 136e and the results are also corrected for bias with NBL CRM 112A uranium metal assay standard. This work describes the assays performed for validation of a Metrohm 836 potentiometric titrator acquired by LASAL in order to improve the analytical methodology of the laboratory. The titrator is attached to a Pt:Rh (90:10) as indicator electrode and a mercurous sulfate as the reference electrode. The evaluation of accuracy and repeatability were made by comparison, the results provided by the titrator with the certified value of standards and also by the participation in round robin program sponsored by New Brunswick Laboratory - NBL. The validation was done by a comparison of the performance between the Metrohm 836 and a Mettler - DL67 titrator which has currently been used by the laboratory. It included evaluation of the results of both equipment, the repeatability of the measurement, any systematic contributions and its uncertainties. (author)

Error assessment in recombinant baculovirus titration: evaluation of different methods.

Science.gov (United States)

Roldão, António; Oliveira, Rui; Carrondo, Manuel J T; Alves, Paula M

2009-07-01

The success of baculovirus/insect cells system in heterologous protein expression depends on the robustness and efficiency of the production workflow. It is essential that process parameters are controlled and include as little variability as possible. The multiplicity of infection (MOI) is the most critical factor since irreproducible MOIs caused by inaccurate estimation of viral titers hinder batch consistency and process optimization. This lack of accuracy is related to intrinsic characteristics of the method such as the inability to distinguish between infectious and non-infectious baculovirus. In this study, several methods for baculovirus titration were compared. The most critical issues identified were the incubation time and cell concentration at the time of infection. These variables influence strongly the accuracy of titers and must be defined for optimal performance of the titration method. Although the standard errors of the methods varied significantly (7-36%), titers were within the same order of magnitude; thus, viral titers can be considered independent of the method of titration. A cost analysis of the baculovirus titration methods used in this study showed that the alamarblue, real time Q-PCR and plaque assays were the most expensive techniques. The remaining methods cost on average 75% less than the former methods. Based on the cost, time and error analysis undertaken in this study, the end-point dilution assay, microculture tetrazolium assay and flow cytometric assay were found to be the techniques that combine all these three main factors better. Nevertheless, it is always recommended to confirm the accuracy of the titration either by comparison with a well characterized baculovirus reference stock or by titration using two different methods and verification of the variability of results.

A titration model for evaluating calcium hydroxide removal techniques

Directory of Open Access Journals (Sweden)

Mark PHILLIPS

2015-02-01

Full Text Available Objective Calcium hydroxide (Ca(OH2 has been used in endodontics as an intracanal medicament due to its antimicrobial effects and its ability to inactivate bacterial endotoxin. The inability to totally remove this intracanal medicament from the root canal system, however, may interfere with the setting of eugenol-based sealers or inhibit bonding of resin to dentin, thus presenting clinical challenges with endodontic treatment. This study used a chemical titration method to measure residual Ca(OH2 left after different endodontic irrigation methods. Material and Methods Eighty-six human canine roots were prepared for obturation. Thirty teeth were filled with known but different amounts of Ca(OH2 for 7 days, which were dissolved out and titrated to quantitate the residual Ca(OH2 recovered from each root to produce a standard curve. Forty-eight of the remaining teeth were filled with equal amounts of Ca(OH2 followed by gross Ca(OH2 removal using hand files and randomized treatment of either: 1 Syringe irrigation; 2 Syringe irrigation with use of an apical file; 3 Syringe irrigation with added 30 s of passive ultrasonic irrigation (PUI, or 4 Syringe irrigation with apical file and PUI (n=12/group. Residual Ca(OH2 was dissolved with glycerin and titrated to measure residual Ca(OH2 left in the root. Results No method completely removed all residual Ca(OH2. The addition of 30 s PUI with or without apical file use removed Ca(OH2 significantly better than irrigation alone. Conclusions This technique allowed quantification of residual Ca(OH2. The use of PUI (with or without apical file resulted in significantly lower Ca(OH2 residue compared to irrigation alone.

Amperometric titration of indium with edta solution in propanol

International Nuclear Information System (INIS)

Gevorgyan, A.M.; Talipov, Sh.T.; Khadeev, V.A.; Kostylev, V.S.; Khadeeva, L.A.

1980-01-01

Optimum conditions have been chosen for titration of indium with EDTA solution in anhydrous propanol and its mixtures with some aprotic solvents using amperometric and point detection. A procedure is suggested of determining indium microcontents in the presence of large amounts of other elements. The procedure is based on its extraction preseparation followed by direct titration in the extract with a standard EDTA solution [ru

An RCT Investigating Patient-Driven Versus Physician-Driven Titration of BIAsp 30 in Patients with Type 2 Diabetes Uncontrolled Using NPH Insulin.

Science.gov (United States)

Chraibi, Abdelmjid; Al-Herz, Shoorook; Nguyen, Bich Dao; Soeatmadji, Djoko W; Shinde, Anil; Lakshmivenkataraman, Balasubramanian; Assaad-Khalil, Samir H

2017-08-01

The aim of this study was to confirm the efficacy of patient-driven titration of BIAsp 30 in terms of glycemic control, by comparing it to physician-driven titration of BIAsp 30, in patients with type 2 diabetes in North Africa, the Middle East, and Asia. A 20-week, open-label, randomized, two-armed, parallel-group, multicenter study in Egypt, Indonesia, Morocco, Saudi Arabia, and Vietnam. Patients (n = 155) with type 2 diabetes inadequately controlled using neutral protamine Hagedorn (NPH) insulin were randomized to either patient-driven or physician-driven BIAsp 30 titration. The noninferiority of patient-driven compared to physician-driven titration with respect to the reduction in HbA1c was confirmed. The estimated mean change in HbA1c from baseline to week 20 was -1.27% in the patient-driven arm and -1.04% in the physician-driven arm, with an estimated treatment difference of -0.23% (95% confidence interval: -0.54; 0.08). After 20 weeks of treatment, the proportions of patients achieving the target of HbA1c titration arms; the proportions of patients achieving the target of ≤6.5% were also similar. Both titration algorithms were well tolerated, and hypoglycemic episode rates were similar in both arms. Patient-driven titration of BIAsp 30 can be as effective and safe as physician-driven titration in non-Western populations. Overall, the switch from NPH insulin to BIAsp 30 was well tolerated in both titration arms and led to improved glycemic control. A limitation of the study was the relatively small number of patients recruited in each country. ClinicalTrials.gov NCT01589653. Novo Nordisk A/S, Denmark.

Two-phase titration of cerium(III) by permanganate

International Nuclear Information System (INIS)

Lazarev, A.I.; Lazareva, V.I.; Gerko, V.V.

1987-01-01

This paper presents a method for the two-phase titrimetric determination of cerium(III) with permanganate which does not require an expenditure of sugar and preliminary removal of chlorides and nitrates. The interaction of cerium(III) with permanganate at room temperature was studied as a function of the pH, the concentration of pyrophosphate, tetraphenylphosphonium (TPP), permanganate, and extraneous compounds, the rate of titration, and the time of stay of the solution in air before titration. The investigations were conducted according to the following methodology: water, solution of cerium(III) pyrophosphate, and TPP were introduced into an Erlenmeyer flask with a side branch near the bottom for clearer observation of the color of the chloroform phase. The authors established the given pH value, poured the water into a volume of 50 ml, and added chloroform. The result was titrated with permanganate solutions of various concentrations until a violet color appeared in the chloroform phase

Determination of boron as boric acid by automatic potentiometric titration

International Nuclear Information System (INIS)

Midgley, D.

1988-06-01

Boron in PWR primary coolant and related waters may be determined as boric acid by titration with sodium hydroxide, using a glass electrode as a pH indicator. With a modern automatic titrator, the analysis is quick, convenient, accurate and precise. In the titration of 8 mg B (e.g. 4 ml of 2000 mg 1 -1 solution), no significant bias was observed and relative standard deviations were about 0.25%. With 0.8 g B, a bias of about 2% appears, although this could be reduced by restandardizing the titrant, but the relative standard deviation was still -1 B, depending on the stage of the fuel cycle. (author)

Comparison of methods for accurate end-point detection of potentiometric titrations

Science.gov (United States)

Villela, R. L. A.; Borges, P. P.; Vyskočil, L.

2015-01-01

Detection of the end point in potentiometric titrations has wide application on experiments that demand very low measurement uncertainties mainly for certifying reference materials. Simulations of experimental coulometric titration data and consequential error analysis of the end-point values were conducted using a programming code. These simulations revealed that the Levenberg-Marquardt method is in general more accurate than the traditional second derivative technique used currently as end-point detection for potentiometric titrations. Performance of the methods will be compared and presented in this paper.

Comparison of methods for accurate end-point detection of potentiometric titrations

International Nuclear Information System (INIS)

Villela, R L A; Borges, P P; Vyskočil, L

2015-01-01

Detection of the end point in potentiometric titrations has wide application on experiments that demand very low measurement uncertainties mainly for certifying reference materials. Simulations of experimental coulometric titration data and consequential error analysis of the end-point values were conducted using a programming code. These simulations revealed that the Levenberg-Marquardt method is in general more accurate than the traditional second derivative technique used currently as end-point detection for potentiometric titrations. Performance of the methods will be compared and presented in this paper

Ruthenium determination in new composite materials by coulometric titration with generated iron(2)

International Nuclear Information System (INIS)

Butakova, N.A.; Oganesyan, L.B.

1983-01-01

A coulometric technique is developed for ruthenium (4) titration with generated iron (2) in a mixture of hydrochloric-, sulfuric- and phosphoric acids with potentiometric and biammetric indication of the final titration point. Bi (3), Pd (2), Nb (5), Pt (4) Pb (2), Rh (3) do not interfere with the titration. Together with Ru (4) titrated are Ir (4), V (5), Au (3). The method is applied to analyze commercial samples of ruthenium dioxides, lead- and bismuth ruthenites, ruthenium pentafluorides containing 30-80% of ruthenium. The Ssub(r) values do not exceed 0.002

The ion-sensitive field effect transistor in rapid acid-base titrations

NARCIS (Netherlands)

Bos, M.; Bergveld, Piet; van Veen-Blaauw, A.M.W.

1979-01-01

Ion-sensitive field effect transistors (ISFETs) are used as the pH sensor in rapid acid—base titrations. Titration speeds at least five times greater than those with glass electrodes are possible for accuracies better than ±1%.

Coulometrische titration von hypochloriten und chloraten.

Science.gov (United States)

Gründler, P; Holzapfel, H

1970-03-01

Hypochlorite was determined by direct coulometric titration with iron(II) in an acetate buffered solution. Chlorate was titrated with titanium(III) in 2M hydrochloric acid. Amperometric indication with one and two electrodes, respectively, was used. Mixtures of hypochlorites and chlorates, e.g., in industrial electrolytes, may be analysed. On a déterminé l'hypochlorite par titrage coulométrique direct avec le fer(II) dans une solution tamponnée à l'acétate. On a titré le chlorate avec le titane(III) en acide chlorhydrique 2M. On a utilisé l'indication ampérométrique une et deux électrodes respectivement. On peut analyser des mélanges d'hypochlorites et de chlorates, par exemple dans des électrolytes industriels.

The coulometric titration of acids and bases in dimethylsulfoxide media

NARCIS (Netherlands)

Bos, M.; IJpma, S.T.; Dahmen, E.A.M.F.

1976-01-01

The coulometric titration of 20–200 μeq of acids and bases in DMSO media is described. In the titration of bases, the electro-oxidation of hydrogen at a platinized platinum electrode is used as the source of protons. The conditions for 100 % current efficiency at this electrode are low current

Simultaneous determination of equivalence volumes and acid dissociation constants from potentiometric titration data.

Science.gov (United States)

Papanastasiou, G; Ziogas, I

1995-06-01

New iterative methods for analysis of potentiometric titration data of (a) mixtures of weak monoprotic acids with their conjugate bases, (b) solutions of polyprotic (di- and triprotic) acids, and (c) mixtures of two diprotic acids are presented. These methods, using data exclusively resulting from the acidic region of the titration curve permits the accurate determination of the analytical concentration of one or more acids even if the titration is stopped well before the end point of the titration. For the titration of a solution containing a conjugate acid/base pair, the proposed procedure enables the extraction of the initial composition of the mixture, as well as the dissociation constant of the concerned acid. Thus, it is possible by this type of analysis to distinguish whether a weak acid has been contaminated by a strong base and define the extent of the contamination. On the other hand, for the titration of polyprotic acids, the proposed approach enables the extraction of the accurate values of the equivalence volume and the dissociation constants K(i) even when the ionization stages overlap. Finally, for the titration of a mixture of two diprotic acids the proposed procedure enables the determination of the composition of the mixture even if the sum of the concentrations of the acids is not known. This method can be used in the analysis of solutions containing two diastereoisomeric forms of a weak diprotic acid. The test of the proposed procedures by means of ideal and Monte Carlo simulated data revealed that these methods are fairly applicable even when the titration data are considerably obscured by 'noise' or contain an important systematic error. The proposed procedures were also successfully applied to experimental titration data.

A model for oxygen conservation associated with titration during pediatric oxygen therapy.

Directory of Open Access Journals (Sweden)

Grace Wu

Full Text Available Continuous oxygen treatment is essential for managing children with hypoxemia, but access to oxygen in low-resource countries remains problematic. Given the high burden of pneumonia in these countries and the fact that flow can be gradually reduced as therapy progresses, oxygen conservation through routine titration warrants exploration.To determine the amount of oxygen saved via titration during oxygen therapy for children with hypoxemic pneumonia.Based on published clinical data, we developed a model of oxygen flow rates needed to manage hypoxemia, assuming recommended flow rate at start of therapy, and comparing total oxygen used with routine titration every 3 minutes or once every 24 hours versus no titration.Titration every 3 minutes or every 24 hours provided oxygen savings estimated at 11.7% ± 5.1% and 8.1% ± 5.1% (average ± standard error of the mean, n = 3, respectively. For every 100 patients, 44 or 30 kiloliters would be saved-equivalent to 733 or 500 hours at 1 liter per minute.Ongoing titration can conserve oxygen, even performed once-daily. While clinical validation is necessary, these findings could provide incentive for the routine use of pulse oximeters for patient management, as well as further development of automated systems.

flower extract as an improvised indicator in acid – base titration

African Journals Online (AJOL)

USER

laboratory practical with an instructional material that is useful, economical, simple and accurate for the said titration. Therefore, it is recommended for integrated science and chemistry instructions. Keywords: Flower, acid, base, indicator, titration. INTRODUCTION. In Nigeria, factors militating against science education.

Effect of Self-monitoring and Medication Self-titration on Systolic Blood Pressure in Hypertensive Patients at High Risk of Cardiovascular Disease

OpenAIRE

McManus, Richard J.; Mant, Jonathan; Haque, M. Sayeed; Bray, Emma P.; Bryan, Stirling; Greenfield, Sheila M.; Jones, Miren I.; Jowett, Sue; Little, Paul; Penaloza, Cristina; Schwartz, Claire; Shackleford, Helen; Shovelton, Claire; Varghese, Jinu; Williams, Bryan

2014-01-01

IMPORTANCE: Self-monitoring of blood pressure with self-titration of antihypertensives (self-management) results in lower blood pressure in patients with hypertension, but there are no data about patients in high-risk groups.\\ud \\ud OBJECTIVE: To determine the effect of self-monitoring with self-titration of antihypertensive medication compared with usual care on systolic blood pressure among patients with cardiovascular disease, diabetes, or chronic kidney disease.\\ud \\ud DESIGN, SETTING, AN...

Null-point titration measurements of free magnesium in stored erythrocytes

International Nuclear Information System (INIS)

Bock, J.L.; Yusuf, Y.; Puntillo, E.

1987-01-01

Free intracellular magnesium concentration (Mg/sub i/) was measured in stored human erythrocytes, using null-point titration with ionophore A23187. For cells stored 31 P NMR spectroscopy, which showed a decrease in Mg/sub i/ with storage. However, the NMR measurements are performed with no pretreatment of the cells, while the null-point method requires an initial washing step, which alters pH/sub i/ and may also alter Mg/sub i/. The titration-measured Mg/sub i/ values are still surprisingly low for long-stored cells, considering that depletion of ATP and 2,3-DPG should release bound Mg. Using the titration-measured Mg/sub i/ values along with measurements of total Mg, ATP, and 2,3-DPG, they estimate that an additional buffer contains about 47% of total Mg in cells stored 21 days. Mg/sub i/ determinations by both 31 P NMR and null-point titration thus indicate that erythrocyte Mg is largely bound to a high-capacity, low-affinity buffer whose relative importance increases during cell storage. Discrepancies between the methods require further investigation

Successful management of a difficult cancer pain patient by appropriate adjuvant and morphine titration

Directory of Open Access Journals (Sweden)

Shiv PS Rana

2011-01-01

Full Text Available Morphine has been used for many years to relieve cancer pain. Oral morphine (in either immediate release or modified release form remains the analgesic of choice for moderate or severe cancer pain. The dose of oral morphine is titrated up to achieve adequate relief from pain with minimal side effects. Antidepressant and anticonvulsant drugs, when used in addition to conventional analgesics, give excellent relief from cancer pain. Most cancer pain responds to pharmacological measures with oral morphine but some pain like neuropathic and bony pain, pain in children and elderly age group, and advanced malignancy pain are very difficult to treat. Here, we report the management of a similar patient of severe cancer pain and the difficulty that we came across during dose titration of oral morphine and adjuvant analgesic.

Acidity titration curves - a versatile tool for the characterisation of acidic mine waste water

International Nuclear Information System (INIS)

Fyson, A.

2000-01-01

Acidity titrations with NaOH are valuable tools for characterisation of acidic mine waters. - Titrations can be used to estimate metal concentrations. - Titrations can be carried out in the field, minimising changes in water chemistry due to sample handling time and procedure. (orig.)

Protometric thermometric titrations of sparingly soluble compounds in water in the presence of n-octanol.

Science.gov (United States)

Burgot, G; Burgot, J-L

2002-10-15

Thermometric titrimetry permits titration of acido-basic compounds in water in the presence of n-octanol. n-Octanol permits the solubilization of protolytes and moreover may also displace the equilibria of the titration reactions. Hydrochlorides of highly insoluble derivatives such as phenothiazine derivatives can be titrated with satisfactory accuracy and precision by sodium hydroxide despite their high pK(a) values. Likewise barbiturate salts can be titrated by hydrochloric acid. In the case of some salts, the methodology may permit the sequential titration of the ion and counter ion. Copyright 2002 Elsevier Science B.V.

Safety of the Up-titration of Nifedipine GITS and Valsartan or Low-dose Combination in Uncontrolled Hypertension: the FOCUS Study.

Science.gov (United States)

Park, Jeong Bae; Shin, Joon-Han; Kim, Dong-Soo; Youn, Ho-Joong; Park, Seung Woo; Shim, Wan Joo; Park, Chang Gyu; Kim, Dong-Woon; Lee, Hae-Young; Choi, Dong-Ju; Rim, Se-Joong; Lee, Sung-Yun; Kim, Ju-Han

2016-04-01

Doubling the dose of antihypertensive drugs is necessary to manage hypertension in patients whose disease is uncontrolled. However, this strategy can result in safety issues. This study compared the safety and efficacy of up-titration of the nifedipine gastrointestinal therapeutic system (GITS) with up-titration of valsartan monotherapy; these were also compared with low-dose combinations of the two therapies. This prospective, open-label, randomized, active-controlled, multicenter study lasted 8 weeks. If patients did not meet the target blood pressure (BP) after 4 weeks of treatment with low-dose monotherapy, they were randomized to up-titration of the nifedipine GITS dose from 30 mg (N30) to 60 mg or valsartan from 80 mg to 160 mg or they were randomized to receive a low-dose combination of N30 and valsartan 80 mg for another 4 weeks. BP variability was assessed by using the SD or the %CV of the short-term BP measured at clinic. Of the 391 patients (20~70 years with stage II or higher hypertension) screened for study inclusion, 362 patients who had 3 BP measurements were enrolled. The reduction in the mean systolic/diastolic BP from baseline to week 4 was similar in both low-dose monotherapy groups with either N30 or valsartan 80 mg. BP variability (SD) was unchanged with either therapy, but the %CV was slightly increased in the N30 group. There was no significant difference in BP variability either in SD or %CV between responders and nonresponders to each monotherapy despite the significant difference in the mean BP changes. The up-titration effect of nifedipine GTS from 30 to 60 mg exhibited an additional BP reduction, but this effect was not shown in the up-titration of valsartan from 80 to 160 mg. Although the difference in BP was obvious between high-dose nifedipine GTS and valsartan, the BP variability was unchanged between the 2 drugs and was similar to the low-dose combinations. There was a low rate of adverse events in all treatment groups. In addition

Kinetic Titration Series with Biolayer Interferometry

Science.gov (United States)

Frenzel, Daniel; Willbold, Dieter

2014-01-01

Biolayer interferometry is a method to analyze protein interactions in real-time. In this study, we illustrate the usefulness to quantitatively analyze high affinity protein ligand interactions employing a kinetic titration series for characterizing the interactions between two pairs of interaction patterns, in particular immunoglobulin G and protein G B1 as well as scFv IC16 and amyloid beta (1–42). Kinetic titration series are commonly used in surface plasmon resonance and involve sequential injections of analyte over a desired concentration range on a single ligand coated sensor chip without waiting for complete dissociation between the injections. We show that applying this method to biolayer interferometry is straightforward and i) circumvents problems in data evaluation caused by unavoidable sensor differences, ii) saves resources and iii) increases throughput if screening a multitude of different analyte/ligand combinations. PMID:25229647

Peer assessment of individual contributions to a group project: Student perceptions

International Nuclear Information System (INIS)

Kench, Peter L.; Field, Nikki; Agudera, Maila; Gill, Margo

2009-01-01

Group work has many benefits for a student's professional development but it is difficult to determine the individual contributions to the group assessment tasks. Peer assessment of an individual's contribution to group work can be used to encourage student participation. It is important that the method of peer assessment is fair and that the students' submissions be treated confidentially. A model for peer assessment of individual contributions to the group assessment is described. Students who did not participate adequately in the group were penalised resulting in a reduced individual grade. Perceptions of the peer assessment method are reported for students enrolled (n = 169) in the subject 'Medical Radiations Project'. The questionnaire showed a positive student response towards the peer assessment model.

Insights into optimal basal insulin titration in type 2 diabetes: Results of a quantitative survey.

Science.gov (United States)

Berard, Lori; Bonnemaire, Mireille; Mical, Marie; Edelman, Steve

2018-02-01

Basal insulin (BI) treatment initiation and dose titration in type 2 diabetes (T2DM) are often delayed. Such "clinical inertia" results in poor glycaemic control and high risk of long-term complications. This survey aimed to determine healthcare professional (HCP) and patient attitudes to BI initiation and titration. An online survey (July-August 2015) including HCPs and patients with T2DM in the USA, France and Germany. Patients were ≥18 years old and had been on BI for 6 to 36 months, or discontinued BI within the previous 12 months. Participants comprised 386 HCPs and 318 people with T2DM. While >75% of HCPs reported discussing titration at the initiation visit, only 16% to 28% of patients remembered such discussions, many (32%-42%) were unaware of the need to titrate BI, and only 28% to 39% recalled mention of the time needed to reach glycaemic goals. Most HCPs and patients agreed that more effective support tools to assist BI initiation/titration are needed; patients indicated that provision of such tools would increase confidence in self-titration. HCPs identified fear of hypoglycaemia, failure to titrate in the absence of symptoms, and low patient motivation as important titration barriers. In contrast, patients identified weight gain, the perception that titration meant worsening disease, frustration over the time to reach HbA1c goals and fear of hypoglycaemia as major factors. A disconnect exists between HCP- and patient-perceived barriers to effective BI titration. To optimize titration, strategies should be targeted to improve HCP-patient communication, and provide support and educational tools. © 2017 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.

Molybdenum (6) determination by the method of high-frequency and pH titration

International Nuclear Information System (INIS)

Lukianets, I.G.; Kulish, N.G.

1981-01-01

A possibility to determine Mo(6) using the method of high frequency and pH-metric titration is investigated. By means of the high frequency contact R-cell Mo(6) titration is performed using different precipitators: 8-oxiquinoline, lead nitrate and acetate and silver nitrate. It is established that the best conditions are achieved during titration of 67.2-1343 mg/10 ml Mo(6) with lead acetate (pH 4.5-6.5). Relative standard deviation Ssub(r) constitutes 0.005 pH-metric titration of Mo(6) with complexone 3 is studied. The range of Mo(6) concentrations determined constitutes 13.43-134.3 mg at pH initial value of 3.5-5.5. Relative standard deviation Ssub(r) constitutes 0.003. Techniques of molybdenum determination in ferromolybdenum using the method of high frequency and pH-metric titration are developed [ru

A fully automatic system for acid-base coulometric titrations

OpenAIRE

Cladera, A.; Caro, A.; Estela, J. M.; Cerdà, V.

1990-01-01

An automatic system for acid-base titrations by electrogeneration of H+ and OH- ions, with potentiometric end-point detection, was developed. The system includes a PC-compatible computer for instrumental control, data acquisition and processing, which allows up to 13 samples to be analysed sequentially with no human intervention. The system performance was tested on the titration of standard solutions, which it carried out with low errors and RSD. It was subsequently applied to the analysis o...

Application of »Mass Titration« to Determination of Surface Charge of Metal Oxides

OpenAIRE

1998-01-01

The mass titration method, used for the point of zero charge determination, was extended to the measurement of the surface charge density. The results agree with the common method, which is the acid-base titration of the colloidal suspension. The advantage of mass titration is that one does not need to perform blank titration, instead one simply adds metal oxide powder to the electrolyte aqueous solution of known pH. To cover the pH range above and below the point of zero charge, two experime...

TITRATION METHOD OF AB0 ANTIBODIES WITH THE USE OF MODERN GEL TECHNOLOGY IN AB0-INCOMPATIBLE TRANSPLANTATION

Directory of Open Access Journals (Sweden)

A. K. Porunova

2014-01-01

Full Text Available It is shown that developed method of titrating AB0 antibodies allows defi ning the titer of the investigational antibodies more precisely on 1–3 dilution of serum compared to the prototype method (titration method of antibodiesin saline medium on the plane. It is more obvious as it excludes hardly interpretable results due to the possibility of conducting visual assessment of agglutination reaction in the gel card thick column and requires less time foranalysis. The results can be saved for comparison with the results of further research. That is not possible under prototype titration method. Aim: our aim is to create a laboratory technique that can accurately, reliably and clearly produce titration of AB0 system antibodies, including in patients with low initial concentration of agglutinins in the blood; a technique more economical in terms of spending serum and that takes less time.Materials and methods: those modes were empirically chosen which allow titration of AB0 system agglutinins using gel technology based micro typing; to titer group antibodies 1640 serum assays of recipients in AB0-incompatibletransplantation were analyzed.The result of the use of specially developed method in organ transplantation from incompatible blood donors consists in enhancing accuracy, sensitivity of natural, complete and incomplete AB0 system immune antibodies titration, in its clarity, using of blood micro-doses for earlier detection of sensitizing of the patient, which is especially important in Pediatrics. Conclusion: the developed procedure of AB0-antibodies’ titration using modern gel technology makes possible a more precise monitoring of the titer of antibodies that is necessary to predict the graft rejection risk, to select the Protocol of preoperative preparation and postoperative management of patients, to assess the effectiveness of therapy in patients for whom it is diffi cult to fi nd a compatible blood type donor, and for whom today AB

End-point detection in potentiometric titration by continuous wavelet transform.

Science.gov (United States)

Jakubowska, Małgorzata; Baś, Bogusław; Kubiak, Władysław W

2009-10-15

The aim of this work was construction of the new wavelet function and verification that a continuous wavelet transform with a specially defined dedicated mother wavelet is a useful tool for precise detection of end-point in a potentiometric titration. The proposed algorithm does not require any initial information about the nature or the type of analyte and/or the shape of the titration curve. The signal imperfection, as well as random noise or spikes has no influence on the operation of the procedure. The optimization of the new algorithm was done using simulated curves and next experimental data were considered. In the case of well-shaped and noise-free titration data, the proposed method gives the same accuracy and precision as commonly used algorithms. But, in the case of noisy or badly shaped curves, the presented approach works good (relative error mainly below 2% and coefficients of variability below 5%) while traditional procedures fail. Therefore, the proposed algorithm may be useful in interpretation of the experimental data and also in automation of the typical titration analysis, specially in the case when random noise interfere with analytical signal.

Dose titration of BAF312 attenuates the initial heart rate reducing effect in healthy subjects.

Science.gov (United States)

Legangneux, Eric; Gardin, Anne; Johns, Donald

2013-03-01

Previous studies have shown transient decreases in heart rate (HR) following administration of sphingosine 1-phosphate (S1P) receptor modulators including BAF312. This study was conducted to determine whether dose titration of BAF312 reduces or eliminates these effects. Fifty-six healthy subjects were randomized 1:1:1:1 to receive BAF312 in one of two dose titration (DT) regimens (DT1 and DT2: 0.25-10 mg over 9-10 days), no titration (10 mg starting dose) or placebo. Pharmacodynamic and pharmacokinetic parameters were assessed. Neither DT1 nor DT2 resulted in clinically significant bradycardia or atrioventricular conduction effects. Both titration regimens showed a favourable difference on each of days 1-12 vs. the non-titration regimen on day 1 for HR effects (P titration was 1.18 (95% confidence interval [CI] 1.13, 1.23) and 1.14 (95% CI 1.09, 1.18) for DT2 (both P titration HRs showed considerable separation from placebo throughout the study. There was no statistically significant reduction in HR vs. placebo on day 1 in either titration regimen. On days 3-7 subjects in DT1 and DT2 experienced minor reductions in HR vs. placebo (approximately 5 beats min⁻¹; P ≤ 0.0001). From days 9-12, HRs in both titration regimens were comparable with placebo. Both titration regimens effectively attenuated the initial bradyarrhythmia observed on day 1 of treatment with BAF312 10 mg. © 2012 Novartis Institutes for BioMedical Research (NIBIR). British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.

Determination of organic bases in non-aqueous solvents by catalytic thermometric titration.

Science.gov (United States)

Vajgand, V J; Kiss, T A; Gaál, F F; Zsigrai, I J

1968-07-01

Catalytic thermometric titrations have been developed for bases (brucine, diethylaniline, potassium acetate and triethylamine) in acetic acid by continuous and discontinuous addition of the standard solution and automatic temperature recording. The determination of weak bases, e.g., antipyrine, unsuccessful in acetic acid by catalytic thermometric titration, has been achieved by using nitromethane or acetic anhydride as solvent. Catalytic thermometric titrations were also performed by coulometric generation of hydrogen ions for the determination of micro amounts of weak bases in a mixture of acetic anhyride and acetic acid.

Integration and global analysis of isothermal titration calorimetry data for studying macromolecular interactions.

Science.gov (United States)

Brautigam, Chad A; Zhao, Huaying; Vargas, Carolyn; Keller, Sandro; Schuck, Peter

2016-05-01

Isothermal titration calorimetry (ITC) is a powerful and widely used method to measure the energetics of macromolecular interactions by recording a thermogram of differential heating power during a titration. However, traditional ITC analysis is limited by stochastic thermogram noise and by the limited information content of a single titration experiment. Here we present a protocol for bias-free thermogram integration based on automated shape analysis of the injection peaks, followed by combination of isotherms from different calorimetric titration experiments into a global analysis, statistical analysis of binding parameters and graphical presentation of the results. This is performed using the integrated public-domain software packages NITPIC, SEDPHAT and GUSSI. The recently developed low-noise thermogram integration approach and global analysis allow for more precise parameter estimates and more reliable quantification of multisite and multicomponent cooperative and competitive interactions. Titration experiments typically take 1-2.5 h each, and global analysis usually takes 10-20 min.

Simple modification of karl-Fischer titration method for determination of water content in colored samples.

Science.gov (United States)

Tavčar, Eva; Turk, Erika; Kreft, Samo

2012-01-01

The most commonly used technique for water content determination is Karl-Fischer titration with electrometric detection, requiring specialized equipment. When appropriate equipment is not available, the method can be performed through visual detection of a titration endpoint, which does not enable an analysis of colored samples. Here, we developed a method with spectrophotometric detection of a titration endpoint, appropriate for moisture determination of colored samples. The reaction takes place in a sealed 4 ml cuvette. Detection is performed at 520 nm. Titration endpoint is determined from the graph of absorbance plotted against titration volume. The method has appropriate reproducibility (RSD = 4.3%), accuracy, and linearity (R(2) = 0.997).

Linear regression analysis of potentiometric titration data for asymmetric redox reactions

International Nuclear Information System (INIS)

Mar'yanov, B.M.; Gavrilenko, M.A.

1997-01-01

A statistical method of processing the curves of potentiometric titration for homogeneous asymmetric redox reactions has been suggested. The method was tested using a model titrimetric system Mohr's salt-K 2 Cr 2 O 7 and was employed for Te determination in an individual solution, semiconductor alloy and CdTe ceramics. Random error of the equivalence point evaluation by the data of a specific titration of 0.1-0.01 M solutions does not exceed 0.3% in case of titration of 0.001 M solutions it increases up to 1.2%. The value of s r varies from 0.0006 to 0.007

Implementation of 'Davies and Gray/NBL Method' for potentiometric titration of uranium in the Safeguards Laboratory of CNEN by the use of a DL-67 mettler titrator

International Nuclear Information System (INIS)

Araujo, Radier Mario Silveira de; Barros, Pedro Dionisio de

2005-01-01

To meet the requirements of the Brazilian State System of Accounting for and Control of Nuclear Materials - SSAC, the Safeguards Laboratory of CNEN - LASAL has been applying the 'Davies and Gray/NBL' method for potentiometric determination of total uranium concentration in uranium samples taken during safeguards inspections at nuclear facilities since 1984, using a Radiometer ETS 822 titrator. In order to improve the analytical capability and the procedures related to the titration methodology, the same method was also implemented by using a METTLER DL - 67 titrator. This equipment is microprocessor - controlled and can be connected to additional devices such as printers, analytical balances, etc. It also provides accurate and reproducible results for end-point titrations, providing analytical performance according to the current international safeguards requirements. The implementation of the method in such equipment included the addition of analytical data as well as the improvement of the equipment parameters for uranium determination. Parameters like predispensing volume; titrant data and end-point value were studied. Some uranium samples (solids and solutions) were used during the initial tests with the titrator. A solution of pure uranyl nitrate was used as reference sample for this paper. From this, aliquots were analyzed in both Radiometer ETS-822 and METTLER DL-67. Results obtained from each equipment were compared with the reference value of the sample. The comparison showed that results from METTLER DL-67 meets the precision and accuracy requirements for this kind of analysis and led to the conclusion that the performance of this titrator is adequate for the determination of total uranium content in samples of nuclear materials for safeguards purposes. (author)

Determination of free acid in U(VI)-Al(III) solution by Gran plot titration

International Nuclear Information System (INIS)

Suh, Moo Yul; Lee, Chang Heon; Sohn, Se Chul; Kim, Jung Suk; Kim, Won Ho; Eom, Tae Yoon

1999-01-01

The determination method of free acid in spent U-Al nuclear fuel solutions by Gran plot titration was described. Effect of U(VI) and Al(III) on the alkalimetric titration of nitric acid was investigation in oxalate complexing media as well as in noncomplexing media. Positive biases were observed in both titration media when the end-point was estimated by the Gran plot method. It was found that the cause of the bias was U(VI) in the oxalate complexing media, but Al(III) in the noncomplexing media. The relative error was less than 1% in the titration of 0.1 M HNO 3 at a U(VI):Al(III):H + mole ratio of up to 2:12:1 as long as the pH of the oxalate titration media was sustained to be below 5.0 at the beginning of titration. The method was successfully applied to the determination of nitric acid in a solution of HANARO reactor fuel with U:Al mole ratio of 1:6

Investigation of iodine liberation process in redox titration of potassium iodate with sodium thiosulfate

International Nuclear Information System (INIS)

Asakai, Toshiaki; Hioki, Akiharu

2011-01-01

Potassium iodate is often used as a reference material to standardize a sodium thiosulfate solution which is a familiar titrant for redox titrations. In the standardization, iodine (triiodide) liberated by potassium iodate in an acidic potassium iodide solution is titrated with a sodium thiosulfate solution. The iodine liberation process is significantly affected by the amount of acid, that of potassium iodide added, the waiting time for the liberation, and light; therefore, the process plays a key role for the accuracy of the titration results. Constant-voltage biamperometry with a modified dual platinum-chip electrode was utilized to monitor the amount of liberated iodine under several liberation conditions. Coulometric titration was utilized to determine the concentration of a sodium thiosulfate solution on an absolute basis. Potassium iodate was assayed by gravimetric titration with the sodium thiosulfate solution under several iodine liberation conditions. The liberation process was discussed from the changes in the apparent assay of potassium iodate. The information of the appropriate titration procedure obtained in the present study is useful for any analysts utilizing potassium iodate to standardize a thiosulfate solution.

Investigation of iodine liberation process in redox titration of potassium iodate with sodium thiosulfate

Energy Technology Data Exchange (ETDEWEB)

Asakai, Toshiaki, E-mail: t-asakai@aist.go.jp [National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 3-9, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563 (Japan); Hioki, Akiharu [National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 3-9, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563 (Japan)

2011-03-09

Potassium iodate is often used as a reference material to standardize a sodium thiosulfate solution which is a familiar titrant for redox titrations. In the standardization, iodine (triiodide) liberated by potassium iodate in an acidic potassium iodide solution is titrated with a sodium thiosulfate solution. The iodine liberation process is significantly affected by the amount of acid, that of potassium iodide added, the waiting time for the liberation, and light; therefore, the process plays a key role for the accuracy of the titration results. Constant-voltage biamperometry with a modified dual platinum-chip electrode was utilized to monitor the amount of liberated iodine under several liberation conditions. Coulometric titration was utilized to determine the concentration of a sodium thiosulfate solution on an absolute basis. Potassium iodate was assayed by gravimetric titration with the sodium thiosulfate solution under several iodine liberation conditions. The liberation process was discussed from the changes in the apparent assay of potassium iodate. The information of the appropriate titration procedure obtained in the present study is useful for any analysts utilizing potassium iodate to standardize a thiosulfate solution.

A microcomputer-controlled system for titration analysis

NARCIS (Netherlands)

Boelema, Gerrit Jan

1982-01-01

This thesis deals with the results of the implementation of microprocessor technology in automatic titration equipment to obtain a versatile system for pharmaceutical, chemical analytical and optimization research purposes. ... Zie: Summary

Statistical evaluation of an interlaboratory comparison for the determination of uranium by potentiometric titration

International Nuclear Information System (INIS)

Ketema, D.J.; Harry, R.J.S.; Zijp, W.L.

1990-09-01

Upon request of the ESARDA working group 'Low enriched uranium conversion - and fuel fabrication plants' an interlaboratory comparison was organized, to assess the precision and accuracy concerning the determination of uranium by the potentiometric titration method. This report presents the results of a statistical evaluation on the data of the first phase of this exercise. (author). 9 refs.; 5 figs.; 24 tabs

Simple Modification of Karl-Fischer Titration Method for Determination of Water Content in Colored Samples

Science.gov (United States)

Tavčar, Eva; Turk, Erika; Kreft, Samo

2012-01-01

The most commonly used technique for water content determination is Karl-Fischer titration with electrometric detection, requiring specialized equipment. When appropriate equipment is not available, the method can be performed through visual detection of a titration endpoint, which does not enable an analysis of colored samples. Here, we developed a method with spectrophotometric detection of a titration endpoint, appropriate for moisture determination of colored samples. The reaction takes place in a sealed 4 ml cuvette. Detection is performed at 520 nm. Titration endpoint is determined from the graph of absorbance plotted against titration volume. The method has appropriate reproducibility (RSD = 4.3%), accuracy, and linearity (R 2 = 0.997). PMID:22567558

Simple Modification of Karl-Fischer Titration Method for Determination of Water Content in Colored Samples

Directory of Open Access Journals (Sweden)

Eva Tavčar

2012-01-01

Full Text Available The most commonly used technique for water content determination is Karl-Fischer titration with electrometric detection, requiring specialized equipment. When appropriate equipment is not available, the method can be performed through visual detection of a titration endpoint, which does not enable an analysis of colored samples. Here, we developed a method with spectrophotometric detection of a titration endpoint, appropriate for moisture determination of colored samples. The reaction takes place in a sealed 4 ml cuvette. Detection is performed at 520 nm. Titration endpoint is determined from the graph of absorbance plotted against titration volume. The method has appropriate reproducibility (RSD=4.3%, accuracy, and linearity (2=0.997.

Increasing the Detection Limit of the Parkinson Disorder through a Specific Surface Chemistry Applied onto Inner Surface of the Titration Well

Directory of Open Access Journals (Sweden)

Fabienne Poncin-Epaillard

2012-04-01

Full Text Available The main objective of this paper was to illustrate the enhancement of the sensitivity of ELISA titration for neurodegenerative proteins by reducing nonspecific adsorptions that could lead to false positives. This goal was obtained thanks to the association of plasma and wet chemistries applied to the inner surface of the titration well. The polypropylene surface was plasma-activated and then, dip-coated with different amphiphilic molecules. These molecules have more or less long hydrocarbon chains and may be charged. The modified surfaces were characterized in terms of hydrophilic—phobic character, surface chemical groups and topography. Finally, the coated wells were tested during the ELISA titration of the specific antibody capture of the α-synuclein protein. The highest sensitivity is obtained with polar (Θ = 35°, negatively charged and smooth inner surface.

Further investigation on the degree of deacetylation of chitosan determined by potentiometric titration

OpenAIRE

Kamal Sweidan; Abdel-Motalleb Jaber; Nawzat Al-jbour; Rana Obaidat; Mayyas Al- Remawi; Adnan Badwan

2011-01-01

The degree of deacetylation (DDA) of various low molecular weight chitosan (LMWC) species as the hydrochloride and free base (amine form) was determined by direct and back potentiometric titration, respectively. The DDA values obtained for the chitosan hydrochloride by direct titration were greater than 93% for all oligomers tested (Molecular weight (Mwt) between about 1.3 to 30.0 kDa). However, the DDA values obtained for chitosan amine oligomers using back titration were significantly lower...

Optimizing Glycemic Control Through Titration of Insulin Glargine 100 U/mL: A Review of Current and Future Approaches with a Focus on Asian Populations.

Science.gov (United States)

Deerochanawong, Chaicharn; Bajpai, Shailendra; Dwipayana, I Made Pande; Hussein, Zanariah; Mabunay, Maria Aileen; Rosales, Reynaldo; Tsai, Shih-Tzer; Tsang, Man Wo

2017-12-01

Various data have demonstrated inadequate glycemic control amongst Asians with type 2 diabetes mellitus (T2DM), possibly on account of suboptimal titration of basal insulin-an issue which needs to be further examined. Here we review the available global and Asia-specific data on titration of basal insulin, with a focus on the use of insulin glargine 100 U/mL (Gla-100). We also discuss clinical evidence on the efficacy and safety of titrating Gla-100, different approaches to titration, including some of the latest technological advancements, and guidance on the titration of basal insulin from international and local Asian guidelines. The authors also provide their recommendations for the initiation and titration of basal insulin for Asian populations. Discussion of the data included in this review and in relation to the authors' clinical experience with treating T2DM in Asian patients is also included. Briefly, clinical studies demonstrate the achievement of adequate glycemic control in adults with T2DM through titration of Gla-100. However, studies investigating approaches to titration, specifically in Asian populations, are lacking and need to be conducted. Given that the management of insulin therapy is a multidisciplinary team effort involving endocrinologists, primary care physicians, nurse educators, and patients, greater resources and education targeted at these groups are needed regarding the optimal titration of basal insulin. Technological advancements in the form of mobile or web-based applications for automated dose adjustment can aid different stakeholders in optimizing the dose of basal insulin, enabling a larger number of patients in Asia to reach their target glycemic goals with improved outcomes.

Acid-base titrations by stepwise addition of equal volumes of titrant with special reference to automatic titrations-II Theory of titration of mixtures of acids, polyprotic acids, acids in mixture with weak bases, and ampholytes.

Science.gov (United States)

Pehrsson, L; Ingman, F; Johansson, S

A general method for evaluating titration data for mixtures of acids and for acids in mixture with weak bases is presented. Procedures are given that do not require absolute [H]-data, i.e., relative [H]-data may be used. In most cases a very rough calibration of the electrode system is enough. Further, for simple systems, very approximate values of the stability constants are sufficient. As examples, the titration of the following are treated in some detail: a mixture of two acids, a diprotic acid, an acid in presence of its conjugate base, and an ampholyte.

A 24-Week, Randomized, Controlled Study to Evaluate the Tolerability, Safety and Efficacy of 2 Different Titration Schemes of the Rivastigmine Patch in Japanese Patients with Mild to Moderate Alzheimer's Disease

Directory of Open Access Journals (Sweden)

Yu Nakamura

2015-09-01

Full Text Available Aim: To investigate whether 1-step titration of the rivastigmine patch (initiated at 5 cm2 and titrated to 10 cm2 after 4 weeks is well tolerated in Japanese patients with Alzheimer's disease (AD as compared to 3-step titration (initiated at 2.5 cm2 and titrated by 2.5 cm2 every 4 weeks to 10 cm2. Methods: A 24-week, multicenter, randomized, double-blind study was conducted in Japan between July 2012 and May 2014. Patients with mild to moderate AD aged 50-85 years were randomized 1:1 to 1-step or 3-step titration of the rivastigmine once-daily patch. The primary endpoint was the proportion of patients with adverse events leading to discontinuation. Results: Of 216 patients randomized, 215 (1-step, n = 107; 3-step, n = 108 were included in the safety analysis. The primary endpoint outcome was 15.0% in the 1-step group and 18.5% in the 3-step group. The observed treatment difference was −3.6% (95% confidence interval: −17.0, 9.6, falling within the prespecified acceptance range. Conclusion: The tolerability of two different titration schemes was similar in Japanese patients with AD.

Contribution of Food Groups to Energy and Nutrient Intakes in Five Developed Countries

Directory of Open Access Journals (Sweden)

Nancy Auestad

2015-06-01

Full Text Available Economic growth in developing countries and globalization of the food sector is leading to increasingly similar food consumption patterns worldwide. The aim of this study was to describe similarities and differences in the contributions of main food groups to energy and nutrient intakes in five developed countries across three continents. We obtained summary reports of national food consumption survey data from Australia, France, Denmark, the Netherlands, and the United States. Survey years spanned 2003–2012; sample size ranged from 1444 to 17,386. To mitigate heterogeneity of food groups across countries, we recategorized each survey’s reported food groups and subgroups into eight main food groups and, for three countries, a ninth “mixed dishes” group. We determined the percent contribution of each food group to mean daily intakes of energy, saturated fat, sodium, fiber, and ten vitamins and minerals that are commonly under-consumed. Differences in findings from surveys utilizing a foods-as-consumed versus a disaggregated or ingredients approach to food group composition and contributions from the milk and milk products group, a source of several under-consumed nutrients, were explored. Patterns of food group contributions to energy and nutrient intakes were generally similar across countries. Some differences were attributable to the analytical approach used by the surveys. For the meat/protein, milk and milk products, vegetables, and fruit groups, percent contributions to key nutrient intakes exceeded percent contributions to energy intake. The mixed dishes group provided 10%–20% of total daily energy and a similar 10%–25% of the daily intake of several nutrients. This descriptive study contributes to an understanding of food group consumption patterns in developed countries.

Contribution of Food Groups to Energy and Nutrient Intakes in Five Developed Countries

Science.gov (United States)

Auestad, Nancy; Hurley, Judith S.; Fulgoni, Victor L.; Schweitzer, Cindy M.

2015-01-01

Economic growth in developing countries and globalization of the food sector is leading to increasingly similar food consumption patterns worldwide. The aim of this study was to describe similarities and differences in the contributions of main food groups to energy and nutrient intakes in five developed countries across three continents. We obtained summary reports of national food consumption survey data from Australia, France, Denmark, the Netherlands, and the United States. Survey years spanned 2003–2012; sample size ranged from 1444 to 17,386. To mitigate heterogeneity of food groups across countries, we recategorized each survey’s reported food groups and subgroups into eight main food groups and, for three countries, a ninth “mixed dishes” group. We determined the percent contribution of each food group to mean daily intakes of energy, saturated fat, sodium, fiber, and ten vitamins and minerals that are commonly under-consumed. Differences in findings from surveys utilizing a foods-as-consumed versus a disaggregated or ingredients approach to food group composition and contributions from the milk and milk products group, a source of several under-consumed nutrients, were explored. Patterns of food group contributions to energy and nutrient intakes were generally similar across countries. Some differences were attributable to the analytical approach used by the surveys. For the meat/protein, milk and milk products, vegetables, and fruit groups, percent contributions to key nutrient intakes exceeded percent contributions to energy intake. The mixed dishes group provided 10%–20% of total daily energy and a similar 10%–25% of the daily intake of several nutrients. This descriptive study contributes to an understanding of food group consumption patterns in developed countries. PMID:26061017

Home blood pressure monitoring and self-titration of antihypertensive medications: Proposed patient selection criteria.

Science.gov (United States)

Hill, James R

2016-05-01

Recent studies have demonstrated that home blood pressure monitoring (HBPM), coupled with self-titration of medications is a viable intervention to control hypertension. There are currently no established criteria to evaluate patients for inclusion in such a program. The purpose of this discussion is to propose criteria for determining if a patient is appropriate to participate in a program of HBPM and self-titration. Inclusion criteria for two self-titration trials were examined, and additional factors in clinical practice were identified and discussed. Additional selection criteria were proposed to support the decision to enroll a patient in an antihypertensive self-titration program. Inclusion criteria from self-titration trials provide a reasonable starting point for choosing appropriate patients in clinical practice, but additional research is necessary. Adaptation of these criteria and consideration of the identified factors can be used to develop decision support instruments. Such instruments should be evaluated for effectiveness and reliability prior to use in clinical practice. HBPM combined with self-titration is an effective patient-centered approach for hypertension management. Decision support instruments to determine appropriate patients are necessary for safe and effective use in clinical practice. ©2015 American Association of Nurse Practitioners.

Free Software Development. 3. Numerical Description of Soft Acid with Soft Base Titration

OpenAIRE

Lorentz JÄNTSCHI; Horea Iustin NAŞCU

2002-01-01

The analytical methods of qualitative and quantitative determination of ions in solutions are very flexible to automation. The present work is focus on modeling the process of titration and presents a numerical simulation of acid-base titration. A PHP program to compute all iterations in titration process that solves a 3th rank equation to find value of pH for was built and is available through http internet protocol at the address: http://vl.academicdirect.org/molecular_dynamics/ab_titra...

Microcalorimetric and potentiometric titration studies on the adsorption of copper by extracellular polymeric substances (EPS), minerals and their composites.

Science.gov (United States)

Fang, Linchuan; Huang, Qiaoyun; Wei, Xing; Liang, Wei; Rong, Xinming; Chen, Wenli; Cai, Peng

2010-08-01

Equilibrium adsorption experiments, isothermal titration calorimetry and potentiometric titration techniques were employed to investigate the adsorption of Cu(II) by extracellular polymeric substances (EPS) extracted from Pseudomonas putida X4, minerals (montmorillonite and goethite) and their composites. Compared with predicted values of Cu(II) adsorption on composites, the measured values of Cu(II) on EPS-montmorillonite composite increased, however, those on EPS-goethite composite decreased. Potentiometric titration results also showed that more surface sites were observed on EPS-montmorillonite composite and less reactive sites were found on EPS-goethite composite. The adsorption of Cu(II) on EPS molecules and their composites with minerals was an endothermic reaction, while that on minerals was exothermic. The positive values of enthalpy change (Delta H) and entropy change (DeltaS) for Cu(II) adsorption on EPS and mineral-EPS composites indicated that Cu(II) mainly interacts with carboxyl and phosphoryl groups as inner-sphere complexes on EPS molecules and their composites with minerals. (c) 2010 Elsevier Ltd. All rights reserved.

The role of titration schedule of topiramate for the development of depression in patients with epilepsy.

Science.gov (United States)

Mula, Marco; Hesdorffer, Dale C; Trimble, Michael; Sander, Josemir W

2009-05-01

To determine whether a fast titration schedule of topiramate (TPM) has different effects on the occurrence of depression, in relation to other risk factors for TPM-induced depression, including history of depression (HxDEP), febrile seizures (FS), and hippocampal sclerosis (HS). Using data from a large case registry of patients prescribed TPM, two models were constructed: Model 1 examined the independent effect of rapid TPM titration after separate adjustment for FS, HxDEP, and HS. Model 2 examined effect of the cooccurrence of rapid titration on the development of depression with each of these risk factors. A total of 423 patients were included (51.8% females), mean age (SD) 35.5 (11.8) years, mean duration of epilepsy of 22.2 (11.5) years. Forty-four patients (10.4%) developed depression during TPM therapy. A rapid TPM titration was associated with 5-fold increased risk of depression that increased to 12.7-fold in the presence of both FS and rapid TPM titration, 23.3-fold in the presence of both HxDEP and rapid TPM titration, and 7.6-fold in the presence of both HS and rapid TPM titration schedule. Our study suggests that a rapid titration schedule is associated with an increased risk of developing depression during TPM therapy. HxDEP and FS are major contraindications to the use of a rapid titration, with a 23.3-fold and 12.7 fold increased risk, respectively.

Method for linearizing the potentiometric curves of precipitation titration in nonaqueous and aqueous-organic solutions

International Nuclear Information System (INIS)

Bykova, L.N.; Chesnokova, O.Ya.; Orlova, M.V.

1995-01-01

The method for linearizing the potentiometric curves of precipitation titration is studied for its application in the determination of halide ions (Cl - , Br - , I - ) in dimethylacetamide, dimethylformamide, in which titration is complicated by additional equilibrium processes. It is found that the method of linearization permits the determination of the titrant volume at the end point of titration to high accuracy in the case of titration curves without a potential jump in the proximity of the equivalent point (5 x 10 -5 M). 3 refs., 2 figs., 3 tabs

Manufacturing of a Secretoneurin Drug Delivery System with Self-Assembled Protamine Nanoparticles by Titration

Science.gov (United States)

Scheicher, Bernhard; Lorenzer, Cornelia; Gegenbauer, Katrin; Partlic, Julia; Andreae, Fritz; Kirsch, Alexander H.; Rosenkranz, Alexander R.; Werzer, Oliver

2016-01-01

Since therapeutic peptides and oligonucleotides are gathering interests as active pharmaceutical ingredients (APIs), nanoparticulate drug delivery systems are becoming of great importance. Thereby, the possibility to design drug delivery systems according to the therapeutic needs of APIs enhances clinical implementation. Over the last years, the focus of our group was laid on protamine-oligonucleotide-nanoparticles (so called proticles), however, the possibility to modify the size, zeta potential or loading efficiencies was limited. Therefore, at the present study we integrated a stepwise addition of protamine (titration) into the formation process of proticles loaded with the angiogenic neuropeptide secretoneurin (SN). A particle size around 130 nm was determined when proticles were assembled by the commonly used protamine addition at once. Through application of the protamine titration process it was possible to modify and adjust the particle size between approx. 120 and 1200 nm (dependent on mass ratio) without influencing the SN loading capacity. Dynamic light scattering pointed out that the difference in particle size was most probably the result of a secondary aggregation. Initially-formed particles of early stages in the titration process aggregated towards bigger assemblies. Atomic-force-microscopy images also revealed differences in morphology along with different particle size. In contrast, the SN loading was only influenced by the applied mass ratio, where a slight saturation effect was observable. Up to 65% of deployed SN could be imbedded into the proticle matrix. An in-vivo biodistribution study (i.m.) showed a retarded distribution of SN from the site of injection after the application of a SN-proticle formulation. Further, it was demonstrated that SN loaded proticles can be successfully freeze-dried and resuspended afterwards. To conclude, the integration of the protamine titration process offers new possibilities for the formulation of proticles in

Titrated Misoprostol Versus Dinoprostone for Labor Induction

African Journals Online (AJOL)

Aim: This study designed to compare titrated misoprostol regarding its safety and efficacy with dinoprostone for induction of labor. ... Statistical analysis done using Student's t-test for quantitative data and ..... induction: A pilot study. Rev Bras ...

A single-beam titration method for the quantification of open-path Fourier transform infrared spectroscopy

International Nuclear Information System (INIS)

Sung, Lung-Yu; Lu, Chia-Jung

2014-01-01

This study introduced a quantitative method that can be used to measure the concentration of analytes directly from a single-beam spectrum of open-path Fourier Transform Infrared Spectroscopy (OP-FTIR). The peak shapes of the analytes in a single-beam spectrum were gradually canceled (i.e., “titrated”) by dividing an aliquot of a standard transmittance spectrum with a known concentration, and the sum of the squared differential synthetic spectrum was calculated as an indicator for the end point of this titration. The quantity of a standard transmittance spectrum that is needed to reach the end point can be used to calculate the concentrations of the analytes. A NIST traceable gas standard containing six known compounds was used to compare the quantitative accuracy of both this titration method and that of a classic least square (CLS) using a closed-cell FTIR spectrum. The continuous FTIR analysis of industrial exhausting stack showed that concentration trends were consistent between the CLS and titration methods. The titration method allowed the quantification to be performed without the need of a clean single-beam background spectrum, which was beneficial for the field measurement of OP-FTIR. Persistent constituents of the atmosphere, such as NH 3 , CH 4 and CO, were successfully quantified using the single-beam titration method with OP-FTIR data that is normally inaccurate when using the CLS method due to the lack of a suitable background spectrum. Also, the synthetic spectrum at the titration end point contained virtually no peaks of analytes, but it did contain the remaining information needed to provide an alternative means of obtaining an ideal single-beam background for OP-FTIR. - Highlights: • Establish single beam titration quantification method for OP-FTIR. • Define the indicator for the end-point of spectrum titration. • An ideal background spectrum can be obtained using single beam titration. • Compare the quantification between titration

Titration Calculations with Computer Algebra Software

Science.gov (United States)

Lachance, Russ; Biaglow, Andrew

2012-01-01

This article examines the symbolic algebraic solution of the titration equations for a diprotic acid, as obtained using "Mathematica," "Maple," and "Mathcad." The equilibrium and conservation equations are solved symbolically by the programs to eliminate the approximations that normally would be performed by the student. Of the three programs,…

Determination of dissolved inorganic species of iodine by spectrophotometric titration

Energy Technology Data Exchange (ETDEWEB)

Pesavento, Maria; Profumo, Antonella; Biesuz, Raffaela

1987-09-01

A method for determining iodate and iodine (+1) in aqueous solutions is proposed. The assay is similar to a previously described method for the determination of iodide and iodine (O), which were titrated with standard iodate in hydrochloric acid solution. A sample solution made 0.5-1.5 M in hydrochloric acid is titrated with a standard iodide solution and monitored spectrophotometrically at 230 nm. The species involved have strong absorbances that are well differentiated at this wavelength. By combining the two titrations it is possible to resolve any mixture of species of iodine in different oxidation states. The precision of the method (standard deviation) is the same both when determining a single species (IO/sub 3/-,I+,1/sub 2/ or I-) and a mixture, and is equal to 2 x 10/sup -7/ M. Chloride and bromide, even at very high concentrations, do not interfere.

Determination of dissolved inorganic species of iodine by spectrophotometric titration

International Nuclear Information System (INIS)

Pesavento, Maria; Profumo, Antonella

1987-01-01

A method for determining iodate and iodine (+1) in aqueous solutions is proposed. The assay is similar to a previously described method for the determination of iodide and iodine (O), which were titrated with standard iodate in hydrochloric acid solution. A sample solution made 0.5-1.5 M in hydrochloric acid is titrated with a standard iodide solution and monitored spectrophotometrically at 230 nm. The species involved have strong absorbances that are well differentiated at this wavelength. By combining the two titrations it is possible to resolve any mixture of species of iodine in different oxidation states. The precision of the method (standard deviation) is the same both when determining a single species (IO 3 -,I+,1 2 or I-) and a mixture, and is equal to 2 x 10 -7 M. Chloride and bromide, even at very high concentrations, do not interfere. (author)

Thermometric titration of cadmium with sodium diethyldithiocarbamate, with oxidation by hydrogen peroxide as indicator reaction.

Science.gov (United States)

Hattori, T; Yoshida, H

1987-08-01

A new method of end-point indication is described for thermometric titration of cadmium with sodium diethyldithiocarbamate (DDTC). It is based on the redox reaction between hydrogen peroxide added to the system before titration, and the first excess of DDTC. Amounts of cadmium in the range 10-50 mumoles are titrated within 1% error.

Process monitored spectrophotometric titration coupled with chemometrics for simultaneous determination of mixtures of weak acids.

Science.gov (United States)

Liao, Lifu; Yang, Jing; Yuan, Jintao

2007-05-15

A new spectrophotometric titration method coupled with chemometrics for the simultaneous determination of mixtures of weak acids has been developed. In this method, the titrant is a mixture of sodium hydroxide and an acid-base indicator, and the indicator is used to monitor the titration process. In a process of titration, both the added volume of titrant and the solution acidity at each titration point can be obtained simultaneously from an absorption spectrum by least square algorithm, and then the concentration of each component in the mixture can be obtained from the titration curves by principal component regression. The method only needs the information of absorbance spectra to obtain the analytical results, and is free of volumetric measurements. The analyses are independent of titration end point and do not need the accurate values of dissociation constants of the indicator and the acids. The method has been applied to the simultaneous determination of the mixtures of benzoic acid and salicylic acid, and the mixtures of phenol, o-chlorophenol and p-chlorophenol with satisfactory results.

Effect of dissolved oxygen on two bacterial pathogens examined using ATR-FTIR spectroscopy, microelectrophoresis, and potentiometric titration.

Science.gov (United States)

Castro, Felipe D; Sedman, Jacqueline; Ismail, Ashraf A; Asadishad, Bahareh; Tufenkji, Nathalie

2010-06-01

The effects of dissolved oxygen tension during bacterial growth and acclimation on the cell surface properties and biochemical composition of the bacterial pathogens Escherichia coli O157:H7 and Yersinia enterocolitica are characterized. Three experimental techniques are used in an effort to understand the influence of bacterial growth and acclimation conditions on cell surface charge and the composition of the bacterial cell: (i) electrophoretic mobility measurements; (ii) potentiometric titration; and (iii) ATR-FTIR spectroscopy. Potentiometric titration data analyzed using chemical speciation software are related to measured electrophoretic mobilities at the pH of interest. Titration of bacterial cells is used to identify the major proton-active functional groups and the overall concentration of these cell surface ligands at the cell membrane. Analysis of titration data shows notable differences between strains and conditions, confirming the appropriateness of this tool for an overall charge characterization. ATR-FTIR spectroscopy of whole cells is used to further characterize the bacterial biochemical composition and macromolecular structures that might be involved in the development of the net surficial charge of the organisms examined. The evaluation of the integrated intensities of HPO(2)(-) and carbohydrate absorption bands in the IR spectra reveals clear differences between growth protocols. Taken together, the three techniques seem to indicate that the dissolved oxygen tension during cell growth or acclimation can noticeably influence the expression of cell surface molecules and the measurable cell surface charge, though in a strain-dependent fashion.

Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method.

Science.gov (United States)

Black, Stuart; Ferrell, Jack R

2017-02-07

Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls cause an increase in viscosity (often referred to as 'aging') during storage of bio-oils. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. Additionally, carbonyls are also responsible for coke formation in bio-oil upgrading processes. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation have long been used for the determination of carbonyl content in pyrolysis bio-oils. Here, we present a modification of the traditional carbonyl oximation procedures that results in less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. While traditional carbonyl oximation methods occur at room temperature, the Faix method presented here occurs at an elevated temperature of 80 °C.

An investigation of the functional groups on the surface of activated carbons

Directory of Open Access Journals (Sweden)

MARYTE DERVINYTE

2004-05-01

Full Text Available Activated carbons were produced in the laboratory from wood using a 20-run Plackett–Burman experimental design for 19 factors. The obtained batches of activated carbon were analysed by potentiometric titration and FTIR spectroscopy to determine the surface functional groups. The results obtained by potentiometric titration displayed the distribution of individual acidity constants of those groups in the pK range. Considering this parameter, the surface functional groups were divided into carboxyl, lactone and phenol. The linear regression equations reflecting the influence of each operation used for the synthesis on the amount of these functional groups in the obtained activated carbons were generated. The FTIR spectra were used in parallel for the evaluation of the amount and the type of the surface functional groups. Relationships between the two data sets obtained by potentiometric titration and FTIR spectroscopy were evaluated by correlation analysis. It was established that the amount of surface functional groups determined by potentiometric titration positively correlates with the intensity of the peaks of hydrophilic functional groups in the FTIR spectra. At the same time, the negative correlation between potentiometrically determined amount of surface functional groups and the intensity of peaks of hydrophobic functional groups was observed. Most probably, these non-polar formations can take part in the interaction of carbon surface with H+/OH- ions and diminish the strength of existent functional groups.

[A double antibody sandwich ELISA based assay for titration of severe fever with thrombocytopenia syndrome virus].

Science.gov (United States)

Liu, Lin; Zhang, Quan-Fu; Li, Chuan; Li, Jian-Dong; Jiang, Xiao-Lin; Zhang, Fu-Shun; Wu, Wei; Liang, Mi-Fang; Li, De-Xin

2013-06-01

To develop an assay for titration of severe fever with thrombocytopenia syndrome virus (SFTSV) based on double antibody sandwich ELISA. A double antibody sandwich ELISA was developed for detection of SFTSV based on SFTSV nucleocapsid (N) protein specific poly- and monoclonal antibodies, procedures were optimized and evaluated. This ELISA based titration assay was compared with fluorescence assasy and plaque assay based titration method. The results suggested that the titers obtained by ELISA based method are consistent with those obtained by IFA based method (R = 0.999) and the plaque assay titration method (R = 0.949). The novel ELISA based titration method with high sensitivity and specificity is easy to manage and perform, and can overcome the subjectivity associated with result determination of the fluorescence assay and plaque assay based methods. The novel ELISA based titration method can also be applied to high throughput detection.

Pregnant teenagers' group: contributions to prenatal care.

Science.gov (United States)

Queiroz, Maria Veraci Oliveira; Menezes, Giselle Maria Duarte; Silva, Thaís Jormanna Pereira; Brasil, Eysler Gonçalves Maia; Silva, Raimunda Magalhães da

2017-06-05

To describe changes in nurses' care following the implementation of a group of pregnant teenagers in prenatal care based on the expectations and experiences of pregnant teenagers. Qualitative and descriptive study conducted from February to November 2013 at a Primary Care Unit in Fortaleza, Ceará, Brazil, through focus groups with 16 adolescents from the group of pregnant women in the second or third trimester of pregnancy. The analysis identified central ideas and units of meanings that formed the categories. The strategy of a group of pregnant teenagers, which provides a space for coexistence and the establishment of ties encourages these individuals to talk about their needs, re-signifying their ties. Educational strategies to promote self-care of pregnant teenagers and care for their babies involve the sharing of experiences, doubts and beliefs. Considerations and suggestions of the adolescents contributed to guide nurses' practice and provide a strategic space of care and support for pregnant adolescents in primary care.

Quick titration of pergolide in cotreatment with domperidone is safe and effective

NARCIS (Netherlands)

Jansen, PAF; Herings, RMC; Samson, MM; Schuurmans-Daemen, LMPJ; Hovestadt, A; Verhaar, HJJ; Van Laar, T; de Vreede, P.

2001-01-01

The purpose of the study was to analyze efficacy and safety of quick pergolide titration combined with domperidone. In an open-label prospective study, pergolide was titrated in 16 days to a maximum of 3 mg/d doses as adjunctive treatment to L-Dopa in 10 elderly patients with Parkinson's disease.

Photometric micro-determination of scandium and lanthanides by direct and successive titration using semi-xylenol orange

International Nuclear Information System (INIS)

Hafez, M.A.E.H.; Eman, M.E.S.M.

1986-01-01

The precision and accuracy attainable in direct titrations of the Sc 3+ , La 3+ or Er 3+ ion with a 0.001 M solution of the disodium salt of EDTA using semi-xylenol orange (SXO) as a metallochromic indicator were studied. Accurate results can be achieved by successive titration. The Sc 3+ ion is titrated at pH 2.4, the pH is adjusted to 5.6-5.9 by adding hexamethylenetetramine buffer solution and the La 3+ ion (or Er 3+ ion) is then titrated. A comparison of SXO and xylenol orange indicators for the successive titration of the Sc 3+ ion and lanthanum or erbium was carried out. (author)

A stable and convenient protein electrophoresis titration device with bubble removing system.

Science.gov (United States)

Zhang, Qiang; Fan, Liu-Yin; Li, Wen-Lin; Cong, Feng-Song; Zhong, Ran; Chen, Jing-Jing; He, Yu-Chen; Xiao, Hua; Cao, Cheng-Xi

2017-07-01

Moving reaction boundary titration (MRBT) has a potential application to immunoassay and protein content analysis with high selectivity. However, air bubbles often impair the accuracy of MRBT, and the leakage of electrolyte greatly decreases the safety and convenience of electrophoretic titration. Addressing these two issues a reliable MRBT device with modified electrolyte chamber of protein titration was designed. Multiphysics computer simulation was conducted for optimization according to two-phase flow. The single chamber was made of two perpendicular cylinders with different diameters. After placing electrophoretic tube, the resident air in the junction next to the gel could be eliminated by a simple fast electrolyte flow. Removing the electrophoretic tube automatically prevented electrolyte leakage at the junction due to the gravity-induced negative pressure within the chamber. Moreover, the numerical simulation and experiments showed that the improved MRBT device has following advantages: (i) easy and rapid setup of electrophoretic tube within 20 s; (ii) simple and quick bubble dissipates from the chamber of titration within 2 s; (iii) no electrolyte leakage from the two chambers: and (iv) accurate protein titration and safe instrumental operation. The developed technique and apparatus greatly improves the performance of the previous MRBT device, and providing a new route toward practical application. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Data processing for potentiometric precipitation titration of mixtures of isovalent ions by linear regression analysis

International Nuclear Information System (INIS)

Mar'yanov, B.M.; Shumar, S.V.; Gavrilenko, M.A.

1994-01-01

A method for the computer processing of the curves of potentiometric differential titration using the precipitation reactions is developed. This method is based on transformation of the titration curve into a line of multiphase regression, whose parameters determine the equivalence points and the solubility products of the formed precipitates. The computational algorithm is tested using experimental curves for the titration of solutions containing Hg(2) and Cd(2) by the solution of sodium diethyldithiocarbamate. The random errors (RSD) for the titration of 1x10 -4 M solutions are in the range of 3-6%. 7 refs.; 2 figs.; 1 tab

Number of independent parameters in the potentiometric titration of humic substances.

Science.gov (United States)

Lenoir, Thomas; Manceau, Alain

2010-03-16

With the advent of high-precision automatic titrators operating in pH stat mode, measuring the mass balance of protons in solid-solution mixtures against the pH of natural and synthetic polyelectrolytes is now routine. However, titration curves of complex molecules typically lack obvious inflection points, which complicates their analysis despite the high-precision measurements. The calculation of site densities and median proton affinity constants (pK) from such data can lead to considerable covariance between fit parameters. Knowing the number of independent parameters that can be freely varied during the least-squares minimization of a model fit to titration data is necessary to improve the model's applicability. This number was calculated for natural organic matter by applying principal component analysis (PCA) to a reference data set of 47 independent titration curves from fulvic and humic acids measured at I = 0.1 M. The complete data set was reconstructed statistically from pH 3.5 to 9.8 with only six parameters, compared to seven or eight generally adjusted with common semi-empirical speciation models for organic matter, and explains correlations that occur with the higher number of parameters. Existing proton-binding models are not necessarily overparametrized, but instead titration data lack the sensitivity needed to quantify the full set of binding properties of humic materials. Model-independent conditional pK values can be obtained directly from the derivative of titration data, and this approach is the most conservative. The apparent proton-binding constants of the 23 fulvic acids (FA) and 24 humic acids (HA) derived from a high-quality polynomial parametrization of the data set are pK(H,COOH)(FA) = 4.18 +/- 0.21, pK(H,Ph-OH)(FA) = 9.29 +/- 0.33, pK(H,COOH)(HA) = 4.49 +/- 0.18, and pK(H,Ph-OH)(HA) = 9.29 +/- 0.38. Their values at other ionic strengths are more reliably calculated with the empirical Davies equation than any existing model fit.

Potentiometric titration of selenic and telluric acids with titanium(III) chloride in nonaqueous solvents

International Nuclear Information System (INIS)

Yoshimura, Chozo; Miyamoto, Kiyoshige

1985-01-01

Selenic and Telluric acids were titrated potentiometrically with titanium(III) chloride solution by using Pt-Cu · Hg bimetallic electrodes in nonaqueous solvents such as N, N-dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA) and the mixtures of these solvents. It was found that selenic and telluric acids were titrated directly at room temperature in DMF solution without hydrochloric acid. The molar ratios of selenic and telluric acids to titanium(III) chloride was 1 : 6. However, the corresponding reactions to SeO 4 2- → SeO 3 2- or TeO 4 2- → TeO 3 2- were not confirmed in the titration curve in DMF. In the titration of selenic acid in mixed solvents of DMF and IPA in 1 : 1 or 1 : 2 ratio, two steps were observed. The first and the second steps were appeared on the titration curve at molar ratios of 1 : 2 and 1 : 6, respectively. It was interpreted that the first step corresponded to the intermediate reaction of SeO 4 2- → SeO 3 2- . Mixed solution of selenic and telluric acids were determined by the proposed method. Three steps were observed on the titration curve. It was interpreted that the first, second and third steps corresponded to the reaction of SeO 4 2- → SeO 3 2- , SeO 3 2- → Se(0), and TeO 4 2- → Te(0), respectively. Less than 5 % of water gave no influence on the titration. (author)

Determination of quaternary ammonium compounds by potentiometric titration with an ionic surfactant electrode: single-laboratory validation.

Science.gov (United States)

Price, Randi; Wan, Ping

2010-01-01

A potentiometric titration for determining the quaternary ammonium compounds (QAC) commonly found in antimicrobial products was validated by a single laboratory. Traditionally, QACs were determined by using a biphasic (chloroform and water) manual titration procedure. Because of safety considerations regarding chloroform, as well as the subjectivity of color indicator-based manual titration determinations, an automatic potentiometric titration procedure was tested with quaternary nitrogen product formulations. By using the Metrohm Titrando system coupled with an ionic surfactant electrode and an Ag/AgCl reference electrode, titrations were performed with various QAC-containing formulation products/matrixes; a standard sodium lauryl sulfate solution was used as the titrant. Results for the products tested are sufficiently reproducible and accurate for the purpose of regulatory product enforcement. The robustness of the method was measured by varying pH levels, as well as by comparing buffered versus unbuffered titration systems. A quantitation range of 1-1000 ppm quaternary nitrogen was established. Eight commercially available antimicrobial products covering a variety of matrixes were assayed; the results obtained were comparable to those obtained by the manual titration method. Recoveries of 94 to 104% were obtained for spiked samples.

Determination of Titratable Acidity in Wine Using Potentiometric, Conductometric, and Photometric Methods

Science.gov (United States)

Volmer, Dietrich A.; Curbani, Luana; Parker, Timothy A.; Garcia, Jennifer; Schultz, Linda D.; Borges, Endler Marcel

2017-01-01

This experiment describes a simple protocol for teaching acid-base titrations using potentiometry, conductivity, and/or photometry to determine end points without an added indicator. The chosen example examines the titratable acidity of a red wine with NaOH. Wines contain anthocyanins, the colors of which change with pH. Importantly, at the…

Interaction of molybdenum (6) with potassium benzyldithiocarbaminate during amperometric titration

International Nuclear Information System (INIS)

Galushko, S.V.; Usatenko, Yu.I.

1975-01-01

The paper is an amperometric study of the mechanism of interaction between molybdenum (VI) and potassium benzyl dithiocarbamate [BDTC] which was based on the use of voltamperometry, electron paramagnetic resonance, infrared spectroscopy, potentiometry and elemental analysis. In amperometric titration Mo(VI) with BDTC (pH 4-2) forms a red compound of low solubility. In more acidic media the intensity of coloration is increased and a violet hue develops. On the basis of the data obtained it is concluded that in the amperometric titration of Mo(VI) with potassium BDTC there is first formation of a Mo(VI) compound, which subsequently acquires a red colour as a result of the reduction of Mo(VI) to Mo(V). It was also established that the degree of reduction is small where titration is carried out in the range pH 4.8-0.1. Quantitative determination of Mo is performed most effectively in slightly acidic media. Mo reacts with potassium BDTC in a ratio of 1:2. (E.P.)

Value of routine investigations to predict loop diuretic down-titration success in stable heart failure.

Science.gov (United States)

Martens, Pieter; Verbrugge, Frederik H; Boonen, Levinia; Nijst, Petra; Dupont, Matthias; Mullens, Wilfried

2018-01-01

Guidelines advocate down-titration of loop diuretics in chronic heart failure (CHF) when patients have no signs of volume overload. Limited data are available on the expected success rate of this practice or how routine diagnostic tests might help steering this process. Fifty ambulatory CHF-patients on stable neurohumoral blocker/diuretic therapy for at least 3months without any clinical sign of volume overload were prospectively included to undergo loop diuretic down-titration. All patients underwent a similar pre-down-titration evaluation consisting of a dyspnea scoring, physical examination, transthoracic echocardiography (diastolic function, right ventricular function, cardiac filling pressures and valvular disease), blood sample (serum creatinine, plasma NT-pro-BNP and neurohormones). Loop diuretic maintenance dose was subsequently reduced by 50% or stopped if dose was ≤40mg furosemide equivalents. Successful down-titration was defined as a persistent dose reduction after 30days without weight increase >1.5kg or new-onset symptoms of worsening heart failure. At 30-day follow-up, down-titration was successful in 62% (n=31). In 12/19 patients exhibiting down-titration failure, this occurred within the first week. Physical examination, transthoracic echocardiography and laboratory analysis had limited predictive capability to detect patients with down-titration success/failure (positive likelihood-ratios below 1.5, or area under the curve [AUC] non-statically different from AUC=0.5). Loop diuretic down-titration is feasible in a majority of stable CHF patients in which the treating clinician felt continuation of loops was unnecessary to sustain euvolemia. Importantly, routine diagnostics which suggest euvolemia, have limited diagnostic impact on the post-test probability. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of total acidity index in bioethanol by automated potentiometric titration; Determinacao do indice de acidez total em bioetanol por titulacao potenciometrica automatizada

Energy Technology Data Exchange (ETDEWEB)

Sobral, Sidney Pereira; Ribeiro, Carla de Matos; Fraga, Isabel Cristina Serta; Goncalves, Mary Ane [Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial (DIMCI/INMETRO), Duque de Caxias, RJ (Brazil). Diretoria de Metrologia Cientifica e Industrial], E-mail: spsobral@inmetro.gov.br

2009-07-01

This paper determines the total acidity index of bioethanol by volumetric titration with potentiometric detection. Also, viewing the optimization of the method, studies are exhibited related to the repeatable, besides the comparison with the colorimetric method with the objective to contribute to the certification of bioethanol reference materials.

Pulsating potentiometric titration technique for assay of dissolved oxygen in water at trace level.

Science.gov (United States)

Sahoo, P; Ananthanarayanan, R; Malathi, N; Rajiniganth, M P; Murali, N; Swaminathan, P

2010-06-11

A simple but high performance potentiometric titration technique using pulsating sensors has been developed for assay of dissolved oxygen (DO) in water samples down to 10.0 microg L(-1) levels. The technique involves Winkler titration chemistry, commonly used for determination of dissolved oxygen in water at mg L(-1) levels, with modification in methodology for accurate detection of end point even at 10.0 microg L(-1) levels DO present in the sample. An indigenously built sampling cum pretreatment vessel has been deployed for collection and chemical fixing of dissolved oxygen in water samples from flowing water line without exposure to air. A potentiometric titration facility using pulsating sensors developed in-house is used to carry out titration. The power of the titration technique has been realised in estimation of very dilute solution of iodine equivalent to 10 microg L(-1) O(2). Finally, several water samples containing dissolved oxygen from mg L(-1) to microg L(-1) levels were successfully analysed with excellent reproducibility using this new technique. The precision in measurement of DO in water at 10 microg L(-1) O(2) level is 0.14 (n=5), RSD: 1.4%. Probably for the first time a potentiometric titration technique has been successfully deployed for assay of dissolved oxygen in water samples at 10 microg L(-1) levels. Copyright 2010 Elsevier B.V. All rights reserved.

Pulsating potentiometric titration technique for assay of dissolved oxygen in water at trace level

International Nuclear Information System (INIS)

Sahoo, P.; Ananthanarayanan, R.; Malathi, N.; Rajiniganth, M.P.; Murali, N.; Swaminathan, P.

2010-01-01

A simple but high performance potentiometric titration technique using pulsating sensors has been developed for assay of dissolved oxygen (DO) in water samples down to 10.0 μg L -1 levels. The technique involves Winkler titration chemistry, commonly used for determination of dissolved oxygen in water at mg L -1 levels, with modification in methodology for accurate detection of end point even at 10.0 μg L -1 levels DO present in the sample. An indigenously built sampling cum pretreatment vessel has been deployed for collection and chemical fixing of dissolved oxygen in water samples from flowing water line without exposure to air. A potentiometric titration facility using pulsating sensors developed in-house is used to carry out titration. The power of the titration technique has been realised in estimation of very dilute solution of iodine equivalent to 10 μg L -1 O 2 . Finally, several water samples containing dissolved oxygen from mg L -1 to μg L -1 levels were successfully analysed with excellent reproducibility using this new technique. The precision in measurement of DO in water at 10 μg L -1 O 2 level is 0.14 (n = 5), RSD: 1.4%. Probably for the first time a potentiometric titration technique has been successfully deployed for assay of dissolved oxygen in water samples at 10 μg L -1 levels.

Determination of uranium and plutonium by sequential potentiometric titration

International Nuclear Information System (INIS)

Kato, Yoshiharu; Takahashi, Masao

1976-01-01

The determination of uranium and plutonium in mixed oxide fuels has been developed by sequential potentiometric titration. A weighed sample of uranium and plutonium oxides is dissolved in a mixture of nitric and hydrofluoric acids and the solution is fumed with sulfuric acid. After the reduction of uranium and plutonium to uranium(IV) and plutonium(III) by chromium(II) sulfate, 5 ml of buffer solution (KCl-HCl, pH 1.0) is added to the solution. Then the solution is diluted to 30 ml with water and the pH of the solution is adjusted to 1.0 -- 1.5 with 1 M sodium hydroxide. The solution is stirred until the oxidation of the excess of chromium(II) by air is completed. After the removal of dissolved oxygen by bubbling nitrogen through the solution for 10 minutes, uranium (IV) is titrated with 0.1 N cerium(IV) sulfate. Then, plutonium is titrated by 0.02 N cerium(IV) sulfate. When a mixture of uranium and plutonium is titrated with 0.1 N potassium dichromate potentiometrically, the potential change at the end point of plutonium is very small and the end point of uranium is also unclear when 0.1 N potassium permanganate is used as a titrant. In the present method, nitrate, fluoride and copper(II) interfere with the determination of plutonium and uranium. Iron interferes quantitatively with the determination of plutonium but not of uranium. Results obtained in applying the proposed method to 50 mg of mixtures of plutonium and uranium ((7.5 -- 50))% Pu were accurate to within 0.15 mg of each element. (auth.)

A reliable and feasible qPCR strategy for titrating AAV vectors.

Science.gov (United States)

Wang, Feng; Cui, Xiuling; Wang, Mingxi; Xiao, Weidong; Xu, Ruian

2013-07-05

Previous studies have revealed that traditional real-time quantitative PCR (qPCR) underestimates adeno-associated virus (AAV) titer. Because the inverted terminal repeat (ITR) exists in all AAV vectors, the only remaining element from the wild genome could form special configurations to interfere with qPCR titration. To solve this problem, a modified and universal qPCR method was tested and established. In this work, there was a great variation in titration of ssAAV2-EGFP (Enhanced Green Fluorescence Protein) and scAAV2-EGFP genome by traditional qPCR. For ssAAV2-EGFP, the highest titer was found by using the targeting EGFP primers and the lowest titer was measured by those targeting bovine growth hormone polyA element (pBGH) primers. Experimental data were reverse for ssAAV2-EGFP and scAAV2-EGFP. Here we report an improved and universal SmaI qPCR method, based on cleaving all ITRs in AAV2 genome by SmaI with several advantages: (1) impact of all ITRs in ssAAV2 and scAAV2 was dismissed; (2) titers increased remarkably, up to 7-fold, especially for scAAV2; (3) the variation of titers was reduced when different primers were applied. A similar phenomenon was also observed in other ssAAV2 and scAAV2 products when the range of titration was at 3×107 to 7×109 V.G/µl in this study. This modified qPCR strategy can increase rAAV' titer and reduce titration variance, possibly become a universal method for titrating AAV vectors.

Characterization of antibody-chelator conjugates: Determination of chelator content by terbium fluorescence titration

Energy Technology Data Exchange (ETDEWEB)

Brandt, K.D.; Schnobrich, K.E.; Johnson, D.K. (Abbott Laboratories, Department 90M, Abbott Park, IL (United States))

1991-01-01

Fluorescence titrations were performed by adding varying mole ratios of terbium(III) to antibody conjugates formed by benzyl isothiocyanate derivatives of three different polyaminopolycarboxylate chelators (NTA, EDTA, and DTPA) and the results compared to values for average chelator content obtained by cobalt-57 binding assays. For two different murine monoclonal antibodies, the average chelator content obtained by terbium fluorescence titration correlated closely with that measured by the cobalt-57 binding assay. It is concluded that lanthanide fluorescence titrations provide a useful alternative to radiometal binding assays for the determination of chelator content in protein-chelator conjugates.

Characterization of antibody-chelator conjugates: Determination of chelator content by terbium fluorescence titration

International Nuclear Information System (INIS)

Brandt, K.D.; Schnobrich, K.E.; Johnson, D.K.

1991-01-01

Fluorescence titrations were performed by adding varying mole ratios of terbium(III) to antibody conjugates formed by benzyl isothiocyanate derivatives of three different polyaminopolycarboxylate chelators (NTA, EDTA, and DTPA) and the results compared to values for average chelator content obtained by cobalt-57 binding assays. For two different murine monoclonal antibodies, the average chelator content obtained by terbium fluorescence titration correlated closely with that measured by the cobalt-57 binding assay. It is concluded that lanthanide fluorescence titrations provide a useful alternative to radiometal binding assays for the determination of chelator content in protein-chelator conjugates

Titration of poly(dA-dT) . poly(dA-dT) in solution at variable NaCl concentration.

Science.gov (United States)

Airoldi, Marta; Boicelli, C Andrea; Cadoni, Fabio; Gennaro, Giuseppe; Giomini, Marcello; Giuliani, Anna M; Giustini, Mauro

2004-10-05

CD and uv absorption data showed that high molecular weight poly(dA-dT) . poly(dA-dT), at 298 K, undergoes an acid-induced transition from B-double helix to random coil in NaCl solutions of different concentrations, ranging from 0.005 to 0.600M. Similarly, titration of the polynucleotide with a strong base causes duplex-to-single strands transition. The base- and acid-induced transitions were both reversible by back-titration (with an acid or, respectively, with a base): the apparent pKa were the same in both directions. However, the number of protons per titratable site (adenine N1) required to reach half-denaturation was in great excess over the stoichiometric value; to a much larger extent, the same effect was observed also for the deprotonation of the N3H sites of thymine. Moreover, in the basic denaturation experiments, at low salt concentrations ([NaCl]acid than calculated was needed to back-titrate the base excess to half-denaturation. Both effects could be qualitatively justified on the basis of the counterion condensation theory of polyelectrolytes and considering the energy barrier created by the negatively charged phosphodiester groups to the penetration of the OH- ions inside the double helix and the screening effect of the Na+ ions on such charges, in the deprotonation experiments.

Determination of polyhexamethylene biguanide hydrochloride using photometric colloidal titration with crystal violet as a color indicator.

Science.gov (United States)

Masadome, Takashi; Miyanishi, Takaaki; Watanabe, Keita; Ueda, Hiroshi; Hattori, Toshiaki

2011-01-01

A solution of polyhexamethylene biguanide hydrochloride (PHMB-HCl) was titrated with a standard solution of potassium poly(vinyl sulfate) (PVSK) using crystal violet (CV) as an photometric indicator cation. The end point was detected by a sharp absorbance change due to an abrupt decrease in the concentration of CV. A linear relationship between the concentration of PHMB-HCl and the end-point volume of the titrant existed in the concentration range from 2 to 10 × 10(-6) eq mol L(-1). Back-titration was based on adding an excess amount of PVSK to a sample solution containing CV, which was titrated with a standard solution of poly(diallyldimethylammonium chloride) (PDADMAC). The calibration curve of the PHMB-HCl concentration to the end point volume of the titrant was also linear in the concentration range from 2 to 8 × 10(-6) eq mol L(-1). Both photometric titrations were applied to the determination of PHMB-HCl in a few contact-lens detergents. Back-titration showed a clear end point, but direct titration showed an unclear end point. The results of the back-titration of PHMB-HCl were compared with the content registered in its labels. 2011 © The Japan Society for Analytical Chemistry

SPECIAL CONSIDERATIONS REGARDING WARFARIN DOSE TITRATION IN PATIENTS WITH ATRIAL FIBRILLATION DEPENDING ON CLINICAL FACTORS

Directory of Open Access Journals (Sweden)

E. L. Artanova

2011-01-01

Full Text Available Aim. To study the relations of clinical characteristics and individual warfarin dose titration in patients with atrial fibrillation. Material and methods. Period of warfarin dose titration was analyzed in 68 patients with atrial fibrillation due to ischemic heart disease. Adjusted warfarin dose in milligram, duration of dose titration in days and maximal international normalized ratio (INR were taken into account. Sex, age, history of myocardial infarction and stroke, concomitant diseases, amiodarone therapy were considered among clinical characteristics. Results. Adjusted warfarin dose was significantly higher in obesity , and it was lower in case of experienced myocardial infarction. The INR highest levels and maximal amplitudes of its fluctuations were observed in patients with thyroid gland nodes and smokers. Period of warfarin dose titration was longer in patients treated with amiodarone. Conclusion. Warfarin dose titration in patients with atrial fibrillation depends on the presence of myocardial infarction, obesity , thyroid nodular changes, smoking and amiodarone treatment.

The formation of amino acid and dipeptide complexes with α-cyclodextrin and cucurbit[6]uril in aqueous solutions studied by titration calorimetry

International Nuclear Information System (INIS)

Buschmann, H.-J.; Schollmeyer, E.; Mutihac, L.

2003-01-01

The complex stabilities and the thermodynamic data for the complexation of α-cyclodextrin and cucurbit[6]uril with some amino acids (glycine, L-alanine, L-valine, L-phenylalanine, 6-amino hexanoic acid, 8-amino octanoic acid, 11-amino undecanoic acid) and dipeptides (glycyl-glycine, glycyl-L-valine, glycyl-L-leucine and glycyl-L-phenylalanine) have been determined in aqueous solution by calorimetric titrations. The complex formation with α-cyclodextrin is mainly favoured by entropic contributions due to the release of water molecules from the cavity of the ligand. The values of the reaction enthalpies are small with the exception of 11-amino undecanoic acid. In case of the ligand cucurbit[6]uril, ion-dipole interactions between the protonated amino groups of the amino acids and the carbonyl groups take place. By steric reasons these interactions are lowered for native amino acids because the polar carboxylic groups are always located outside the hydrophobic cavity of cucurbit[6]uril. The complexes of both ligands with dipeptides in water are characterised by hydrophobic interactions and in case of cucurbit[6]uril by additional ion-dipole interactions

Electrophoretic separation of alginic sodium diester and sodium hexametaphosphate in chondroitin sulfate that interfere with the cetylpyridinium chloride titration assay.

Science.gov (United States)

Weiguo, Zhang; Giancaspro, Gabriel; Adams, Kristie M; Neal-Kababick, James; Hildreth, Jana; Li, Aishan; Roman, Mark C; Betz, Joseph M

2014-01-01

The most commonly used chondroitin sulfate (CS) assay method is cetylpyridinium chloride (CPC) titration. Cellulose acetate membrane electrophoresis (CAME) is the technique used for detection of impurities in the U.S. Pharmacopeia's CS monograph. Because CPC titration is a relatively nonspecific quantitative technique, the apparent amount of CS as determined by CPC titration alone may not reflect the true amount of CS due to possible interference with the CPC assay by impurities that contain CPC titratable functional groups. When CAME is used in conjunction with CPC titration, certain non-CS and adulterants can be visualized and estimated, and a true value for CS can be assigned once the presence of these non-CS impurities has been ruled out. This study examines conjunct application of CPC and CAME in ascertaining CS assay and purity in the presence of certain adulterants. These include propylene glycol alginate sulfate sodium, known in commerce as alginic sodium diester (ASD), and Zero One (Z1), a water-soluble agent newly reported in the CS marketplace and subsequently identified as sodium hexametaphosphate. ASD, Z1, and CS are similar in physical appearance and solubility in water and ethanol. They are also titratable anions and form ionic pairs with CPC, therefore interfering with the CPC titration assay for CS CAME separates these adulterants from each other and from CS by differences in their electrophoretic mobility. CAME is able to detect these impurities in CS at levels as low as 0.66% by weight. Although it is recommended that a method for detecting impurities (e.g., CAME) be used in cormbination with relatively nonspecific assay methods such as CPC titration, this is seldom done in practice. Assay results for CS derived fromn CPC titration may, therefore, be misleading, leaving the CS supply chain vulnerable to adulteration. In this study, the authors investigated ASD and Z1 adulteration of CS and developed an electrophoretic separation of these

SPECIAL CONSIDERATIONS REGARDING WARFARIN DOSE TITRATION IN PATIENTS WITH ATRIAL FIBRILLATION DEPENDING ON CLINICAL FACTORS

OpenAIRE

E. L. Artanova; E. V. Saleeva; I. M. Sokolov; Y. G. Shvarts

2011-01-01

Aim. To study the relations of clinical characteristics and individual warfarin dose titration in patients with atrial fibrillation. Material and methods. Period of warfarin dose titration was analyzed in 68 patients with atrial fibrillation due to ischemic heart disease. Adjusted warfarin dose in milligram, duration of dose titration in days and maximal international normalized ratio (INR) were taken into account. Sex, age, history of myocardial infarction and stroke, concomitant diseases, a...

Simple Modification of Karl-Fischer Titration Method for Determination of Water Content in Colored Samples

OpenAIRE

Eva Tavčar; Erika Turk; Samo Kreft

2012-01-01

The most commonly used technique for water content determination is Karl-Fischer titration with electrometric detection, requiring specialized equipment. When appropriate equipment is not available, the method can be performed through visual detection of a titration endpoint, which does not enable an analysis of colored samples. Here, we developed a method with spectrophotometric detection of a titration endpoint, appropriate for moisture determination of colored samples. The reaction takes p...

Potentiometric Measurement of Transition Ranges and Titration Errors for Acid/Base Indicators

Science.gov (United States)

Flowers, Paul A.

1997-07-01

Sophomore analytical chemistry courses typically devote a substantial amount of lecture time to acid/base equilibrium theory, and usually include at least one laboratory project employing potentiometric titrations. In an effort to provide students a laboratory experience that more directly supports their classroom discussions on this important topic, an experiment involving potentiometric measurement of transition ranges and titration errors for common acid/base indicators has been developed. The pH and visually-assessed color of a millimolar strong acid/base system are monitored as a function of added titrant volume, and the resultant data plotted to permit determination of the indicator's transition range and associated titration error. Student response is typically quite positive, and the measured quantities correlate reasonably well to literature values.

A knowledge based advisory system for acid/base titrations in non-aqueous solvents

NARCIS (Netherlands)

Bos, M.; van der Linden, W.E.

1996-01-01

A computer program was developed that could advice on the choice of solvent and titrant for acid/base titrations in nonaqueous media. It is shown that the feasibility of a titration in a given solvent can be calculated from solvent properties and intrinsic acid/base properties of the sample

Titration ELISA as a Method to Determine the Dissociation Constant of Receptor Ligand Interaction.

Science.gov (United States)

Eble, Johannes A

2018-02-15

The dissociation constant describes the interaction between two partners in the binding equilibrium and is a measure of their affinity. It is a crucial parameter to compare different ligands, e.g., competitive inhibitors, protein isoforms and mutants, for their binding strength to a binding partner. Dissociation constants are determined by plotting concentrations of bound versus free ligand as binding curves. In contrast, titration curves, in which a signal that is proportional to the concentration of bound ligand is plotted against the total concentration of added ligand, are much easier to record. The signal can be detected spectroscopically and by enzyme-linked immunosorbent assay (ELISA). This is exemplified in a protocol for a titration ELISA that measures the binding of the snake venom-derived rhodocetin to its immobilized target domain of α2β1 integrin. Titration ELISAs are versatile and widely used. Any pair of interacting proteins can be used as immobilized receptor and soluble ligand, provided that both proteins are pure, and their concentrations are known. The difficulty so far has been to determine the dissociation constant from a titration curve. In this study, a mathematical function underlying titration curves is introduced. Without any error-prone graphical estimation of a saturation yield, this algorithm allows processing of the raw data (signal intensities at different concentrations of added ligand) directly by mathematical evaluation via non-linear regression. Thus, several titration curves can be recorded simultaneously and transformed into a set of characteristic parameters, among them the dissociation constant and the concentration of binding-active receptor, and they can be evaluated statistically. When combined with this algorithm, titration ELISAs gain the advantage of directly presenting the dissociation constant. Therefore, they may be used more efficiently in the future.

Titrated flow versus fixed flow Bubble Nasal CPAP for respiratory distress in preterm neonates.

Directory of Open Access Journals (Sweden)

Srinivas eMurki

2015-10-01

Full Text Available Background: The clinical effects of a pre-fixed flow of air-oxygen versus a flow titrated according to visible bubbling are not well understood.Objective: To compare the effects of a fixed flow (5 L/min and titrated flow ( flow just enough to ensure bubbling at different set pressures on delivered intra-prong pressure, gas exchange and clinical parameters in preterm infants on bubble CPAP for respiratory distress.Methods: Preterm infants less than 35 weeks gestation on bubble CPAP and less than 96 h of age, were enrolled in this cross over study. They were subjected to 30 minute periods of titrated flow and fixed flow. At the end of both epochs, gas flow rate, set pressure, FiO2, SpO2, Silverman retraction score, respiratory rate , abdominal girth, and blood gases were recorded. The delivered intra-prong pressure was measured by an electronic manometer. Results: Sixty nine recordings were made in 54 infants. For each of the set CPAP pressures (4, 5 and 6 cm H2O, the mean delivered pressure with a fixed flow of 5 L/min was higher than that delivered by the titrated flow. During the fixed flow epoch, the delivered pressure was closer to and higher than the set pressure resulting in higher PaO2 and lower PaCO2 as compared to titrated flow epoch. In the titrated flow period, the delivered pressure was consistently lower than the set pressure. Conclusion: In preterm infants on bubble CPAP with set pressures of 4 to 6 cm H2O, a fixed flow of 5 L/min is more effective than a flow titrated to ensure adequate visible bubbling. It achieves higher delivered pressures, better oxygenation and ventilation.

Plutonium titration by controlled potential coulometry; Dosage du plutonium par coulometrie a potentiel impose

Energy Technology Data Exchange (ETDEWEB)

Leguay, N.

2011-07-01

The LAMMAN (Nuclear Materials Metrology Laboratory) is the support laboratory of the CETAMA (Analytical Method Committee), whose two main activities are developing analytic methods, and making and characterizing reference materials. The LAMMAN chose to develop the controlled potential coulometry because it is a very accurate analytical technique which allows the connection between the quantity of element electrolysed to the quantity of electricity measured thanks to the Faraday's law: it does not require the use of a chemical standard. This method was first used for the plutonium titration and was developed in the Materials Analysis and Metrology Laboratory (LAMM), for upgrading its performances and developing it to the titration of other actinides. The equipment and the material used were developed to allow the work in confined atmosphere (in a glove box), with all the restrictions involved. Plutonium standard solutions are used to qualify the method, and in particular to do titrations with an uncertainty better than 0.1 %. The present study allowed making a bibliographic research about controlled potential coulometry applied to the actinides (plutonium, uranium, neptunium, americium and curium). A full procedure was written to set all the steps of plutonium titration, from the preparation of samples to equipments storage. A method validation was done to check the full procedure, and the experimental conditions: working range, uncertainty, performance... Coulometric titration of the plutonium from pure solution (without interfering elements) was developed to the coulometric titration of the plutonium in presence of uranium, which allows to do accurate analyses for the analyses of some parts of the reprocessing of the spent nuclear fuel. The possibility of developing this method to other actinides than plutonium was highlighted thanks to voltammetric studies, like the coulometric titration of uranium with a working carbon electrode in sulphuric medium. (author)

Determination of the aggregation number for micelles by isothermal titration calorimetry

DEFF Research Database (Denmark)

Olesen, Niels Erik; Holm, Rene; Westh, Peter

2014-01-01

Isothermal titration calorimetry (ITC) has previously been applied to estimate the aggregation number (n), Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of micellization. However, some difficulties of micelle characterization by ITC still remain; most micelles have aggregation numbers...... insight into optimal design of titration protocols for micelle characterization. By applying the new method, the aggregation number of sodium dodecyl sulphate and glycochenodeoxycholate was determined at concentrations around their critical micelle concentration (CMC)...

High frequency titration in non-aqueous solvents. Application to HF and UF6

International Nuclear Information System (INIS)

Neveu, Claude

1965-01-01

In this research thesis, the author first presents the main theoretical notions regarding high frequency titration, notably by studying characteristic curves, i.e. the titration meter indication with respect to conductibility. He reports the use of this method for the study of various reactions in non-aqueous medium: reaction of AlCl 3 with pyridine in acetonitrile, of AlCl 3 with HCl in tetrachloroethane and in nitromethane. He also reports the attempt of application of this method to the titration of HF in presence of UF 6 in CCl 4 as solvent, or by using F acceptors like BF 3 , PF 5 or ClF 3 as reactants [fr

Protofit: A program for determining surface protonation constants from titration data

Science.gov (United States)

Turner, Benjamin F.; Fein, Jeremy B.

2006-11-01

Determining the surface protonation behavior of natural adsorbents is essential to understand how they interact with their environments. ProtoFit is a tool for analysis of acid-base titration data and optimization of surface protonation models. The program offers a number of useful features including: (1) enables visualization of adsorbent buffering behavior; (2) uses an optimization approach independent of starting titration conditions or initial surface charge; (3) does not require an initial surface charge to be defined or to be treated as an optimizable parameter; (4) includes an error analysis intrinsically as part of the computational methods; and (5) generates simulated titration curves for comparison with observation. ProtoFit will typically be run through ProtoFit-GUI, a graphical user interface providing user-friendly control of model optimization, simulation, and data visualization. ProtoFit calculates an adsorbent proton buffering value as a function of pH from raw titration data (including pH and volume of acid or base added). The data is reduced to a form where the protons required to change the pH of the solution are subtracted out, leaving protons exchanged between solution and surface per unit mass of adsorbent as a function of pH. The buffering intensity function Qads* is calculated as the instantaneous slope of this reduced titration curve. Parameters for a surface complexation model are obtained by minimizing the sum of squares between the modeled (i.e. simulated) buffering intensity curve and the experimental data. The variance in the slope estimate, intrinsically produced as part of the Qads* calculation, can be used to weight the sum of squares calculation between the measured buffering intensity and a simulated curve. Effects of analytical error on data visualization and model optimization are discussed. Examples are provided of using ProtoFit for data visualization, model optimization, and model evaluation.

Acid-base titrations using microfluidic paper-based analytical devices.

Science.gov (United States)

Karita, Shingo; Kaneta, Takashi

2014-12-16

Rapid and simple acid-base titration was accomplished using a novel microfluidic paper-based analytical device (μPAD). The μPAD was fabricated by wax printing and consisted of ten reservoirs for reaction and detection. The reaction reservoirs contained various amounts of a primary standard substance, potassium hydrogen phthalate (KHPth), whereas a constant amount of phenolphthalein was added to all the detection reservoirs. A sample solution containing NaOH was dropped onto the center of the μPAD and was allowed to spread to the reaction reservoirs where the KHPth neutralized it. When the amount of NaOH exceeded that of the KHPth in the reaction reservoirs, unneutralized hydroxide ion penetrated the detection reservoirs, resulting in a color reaction from the phenolphthalein. Therefore, the number of the detection reservoirs with no color change determined the concentration of the NaOH in the sample solution. The titration was completed within 1 min by visually determining the end point, which required neither instrumentation nor software. The volumes of the KHPth and phenolphthalein solutions added to the corresponding reservoirs were optimized to obtain reproducible and accurate results for the concentration of NaOH. The μPADs determined the concentration of NaOH at orders of magnitude ranging from 0.01 to 1 M. An acid sample, HCl, was also determined using Na2CO3 as a primary standard substance instead of KHPth. Furthermore, the μPAD was applicable to the titrations of nitric acid, sulfuric acid, acetic acid, and ammonia solutions. The μPADs were stable for more than 1 month when stored in darkness at room temperature, although this was reduced to only 5 days under daylight conditions. The analysis of acidic hot spring water was also demonstrated in the field using the μPAD, and the results agreed well with those obtained by classic acid-base titration.

Design of a multicentre randomized controlled trial to assess the safety and efficacy of dose titration by specialized nurses in patients with heart failure. ETIFIC study protocol.

Science.gov (United States)

Oyanguren, Juana; García-Garrido, LLuisa; Nebot Margalef, Magdalena; Lekuona, Iñaki; Comin-Colet, Josep; Manito, Nicolás; Roure, Julia; Ruiz Rodriguez, Pilar; Enjuanes, Cristina; Latorre, Pedro; Torcal Laguna, Jesús; García-Gutiérrez, Susana

2017-11-01

Heart failure (HF) is associated with many hospital admissions and relatively high mortality, rates decreasing with administration of beta-blockers (BBs), angiotensin-converting-enzyme inhibitors, angiotensin II receptor blockers, and mineralocorticoid receptor antagonists. The effect is dose dependent, suboptimal doses being common in clinical practice. The 2012 European guidelines recommend close monitoring and dose titration by HF nurses. Our main aim is to compare BB doses achieved by patients after 4 months in intervention (HF nurse-managed) and control (cardiologist-managed) groups. Secondary aims include comparing doses of the other aforementioned drugs achieved after 4 months, adverse events, and outcomes at 6 months in the two groups. We have designed a multicentre (20 hospitals) non-inferiority randomized controlled trial, including patients with new-onset HF, left ventricular ejection fraction ≤40%, and New York Heart Association class II-III, with no contraindications to BBs. We will also conduct qualitative analysis to explore potential barriers to and facilitators of dose titration by HF nurses. In the intervention group, HF nurses will implement titration as prescribed by cardiologists, following a protocol. In controls, cardiologists will both prescribe and titrate doses. The study variables are doses of each of the drugs after 4 months relative to the target dose (%), New York Heart Association class, left ventricular ejection fraction, N-terminal pro B-type natriuretic peptide levels, 6 min walk distance, comorbidities, renal function, readmissions, mortality, quality of life, and psychosocial characteristics. The trial seeks to assess whether titration by HF nurses of drugs recommended in practice guidelines is safe and not inferior to direct management by cardiologists. The results could have an impact on clinical practice. © 2017 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of

Acid Rain Analysis by Standard Addition Titration.

Science.gov (United States)

Ophardt, Charles E.

1985-01-01

The standard addition titration is a precise and rapid method for the determination of the acidity in rain or snow samples. The method requires use of a standard buret, a pH meter, and Gran's plot to determine the equivalence point. Experimental procedures used and typical results obtained are presented. (JN)

A General Simulator for Acid-Base Titrations

Science.gov (United States)

de Levie, Robert

1999-07-01

General formal expressions are provided to facilitate the automatic computer calculation of acid-base titration curves of arbitrary mixtures of acids, bases, and salts, without and with activity corrections based on the Davies equation. Explicit relations are also given for the buffer strength of mixtures of acids, bases, and salts.

The acid-base titration of montmorillonite

Science.gov (United States)

Bourg, I. C.; Sposito, G.; Bourg, A. C.

2003-12-01

Proton binding to clay minerals plays an important role in the chemical reactivity of soils (e.g., acidification, retention of nutrients or pollutants). If should also affect the performance of clay barriers for waste disposal. The surface acidity of clay minerals is commonly modelled empirically by assuming generic amphoteric surface sites (>SOH) on a flat surface, with fitted site densities and acidity constant. Current advances in experimental methods (notably spectroscopy) are rapidly improving our understanding of the structure and reactivity of the surface of clay minerals (arrangement of the particles, nature of the reactive surface sites, adsorption mechanisms). These developments are motivated by the difficulty of modelling the surface chemistry of mineral surfaces at the macro-scale (e.g., adsorption or titration) without a detailed (molecular-scale) picture of the mechanisms, and should be progressively incorporated into surface complexation models. In this view, we have combined recent estimates of montmorillonite surface properties (surface site density and structure, edge surface area, surface electrostatic potential) with surface site acidities obtained from the titration of alpha-Al2O3 and SiO2, and a novel method of accounting for the unknown initial net proton surface charge of the solid. The model predictions were compared to experimental titrations of SWy-1 montmorillonite and purified MX-80 bentonite in 0.1-0.5 mol/L NaClO4 and 0.005-0.5 mol/L NaNO3 background electrolytes, respectively. Most of the experimental data were appropriately described by the model after we adjusted a single parameter (silanol sites on the surface of montmorillonite were made to be slightly more acidic than those of silica). At low ionic strength and acidic pH the model underestimated the buffering capacity of the montmorillonite, perhaps due to clay swelling or to the interlayer adsorption of dissolved aluminum. The agreement between our model and the experimental

Laboratory Automatic Titration of Chromium Plating and Electropolishing Solutions

National Research Council Canada - National Science Library

Sopok, Samuel

2001-01-01

.... The analytical chemistry literature lacks an adequate automatic titration method for the monitoring of chromic acid in chromium plating solutions and the monitoring of phosphoric and sulfuric acids...

Non-Aqueous Titration Method for Determining Suppressor Concentration in the MCU Next Generation Solvent (NGS)

International Nuclear Information System (INIS)

Taylor-Pashow, Kathryn M. L.; Jones, Daniel H.

2017-01-01

A non-aqueous titration method has been used for quantifying the suppressor concentration in the MCU solvent hold tank (SHT) monthly samples since the Next Generation Solvent (NGS) was implemented in 2013. The titration method measures the concentration of the NGS suppressor (TiDG) as well as the residual tri-n-octylamine (TOA) that is a carryover from the previous solvent. As the TOA concentration has decreased over time, it has become difficult to resolve the TiDG equivalence point as the TOA equivalence point has moved closer. In recent samples, the TiDG equivalence point could not be resolved, and therefore, the TiDG concentration was determined by subtracting the TOA concentration as measured by semi-volatile organic analysis (SVOA) from the total base concentration as measured by titration. In order to improve the titration method so that the TiDG concentration can be measured directly, without the need for the SVOA data, a new method has been developed that involves spiking of the sample with additional TOA to further separate the two equivalence points in the titration. This method has been demonstrated on four recent SHT samples and comparison to results obtained using the SVOA TOA subtraction method shows good agreement. Therefore, it is recommended that the titration procedure be revised to include the TOA spike addition, and this to become the primary method for quantifying the TiDG.

Non-Aqueous Titration Method for Determining Suppressor Concentration in the MCU Next Generation Solvent (NGS)

Energy Technology Data Exchange (ETDEWEB)

Taylor-Pashow, Kathryn M. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Jones, Daniel H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-10-23

A non-aqueous titration method has been used for quantifying the suppressor concentration in the MCU solvent hold tank (SHT) monthly samples since the Next Generation Solvent (NGS) was implemented in 2013. The titration method measures the concentration of the NGS suppressor (TiDG) as well as the residual tri-n-octylamine (TOA) that is a carryover from the previous solvent. As the TOA concentration has decreased over time, it has become difficult to resolve the TiDG equivalence point as the TOA equivalence point has moved closer. In recent samples, the TiDG equivalence point could not be resolved, and therefore, the TiDG concentration was determined by subtracting the TOA concentration as measured by semi-volatile organic analysis (SVOA) from the total base concentration as measured by titration. In order to improve the titration method so that the TiDG concentration can be measured directly, without the need for the SVOA data, a new method has been developed that involves spiking of the sample with additional TOA to further separate the two equivalence points in the titration. This method has been demonstrated on four recent SHT samples and comparison to results obtained using the SVOA TOA subtraction method shows good agreement. Therefore, it is recommended that the titration procedure be revised to include the TOA spike addition, and this to become the primary method for quantifying the TiDG.

Down-titration of biologics for the treatment of rheumatoid arthritis: a systematic literature review.

Science.gov (United States)

Lau, Chak Sing; Gibofsky, Allan; Damjanov, Nemanja; Lula, Sadiq; Marshall, Lisa; Jones, Heather; Emery, Paul

2017-11-01

Biologic therapies have improved the management of rheumatoid arthritis (RA) and the treat-to-target approach has resulted in many patients achieving remission. In the current treatment landscape, clinicians have begun considering dose reduction/tapering for their patients. Rheumatology guidelines in Asia, Europe, and the United States include down-titration of biologics but admit that the level of evidence is moderate. We conducted a systematic literature review to assess the published studies that evaluate down-titration of biologics in RA. The published literature was searched for studies that down-titrated the following biologics: abatacept, adalimumab, certolizumab, etanercept, golimumab, infliximab, rituximab, and tocilizumab. Eligible studies included randomized controlled trials (RCTs), non-RCTs, observational, and pharmacoeconomic studies. The outcomes of interest were (1) efficacy and health-related quality of life, (2) disease flares, and (3) impact on cost. Eleven full-text publications were identified; only three were RCTs. Study results suggest that dosing down may be an option in many patients who have achieved remission or low disease activity. However, some patients are likely to experience a disease flare. Across the studies, the definition of disease flare and the down-titration criteria were inconsistent, making it difficult to conclude which patients may be appropriate and when to attempt down-titration. Studies have evaluated the practice of dosing down biologic therapy in patients with RA; however, a relatively small number of RCTs have been published. Although down-titration may be an option for some patients in LDA or remission, additional RCTs are needed to provide guidance on this practice.

Automated Potentiometric Titrations in KCl/Water-Saturated Octanol: Method for Quantifying Factors Influencing Ion-Pair Partitioning

Science.gov (United States)

2009-01-01

The knowledge base of factors influencing ion pair partitioning is very sparse, primarily because of the difficulty in determining accurate log PI values of desirable low molecular weight (MW) reference compounds. We have developed a potentiometric titration procedure in KCl/water-saturated octanol that provides a link to log PI through the thermodynamic cycle of ionization and partitioning. These titrations have the advantage of being independent of the magnitude of log P, while maintaining a reproducibility of a few hundredths of a log P in the calculated difference between log P neutral and log P ion pair (diff (log PN − I)). Simple model compounds can be used. The titration procedure is described in detail, along with a program for calculating pKa′′ values incorporating the ionization of water in octanol. Hydrogen bonding and steric factors have a greater influence on ion pairs than they do on neutral species, yet these factors are missing from current programs used to calculate log PI and log D. In contrast to the common assumption that diff (log PN − I) is the same for all amines, they can actually vary more than 3 log units, as in our examples. A major factor affecting log PI is the ability of water and the counterion to approach the charge center. Bulky substituents near the charge center have a negative influence on log PI. On the other hand, hydrogen bonding groups near the charge center have the opposite effect by lowering the free energy of the ion pair. The use of this titration method to determine substituent ion pair stabilization values (IPS) should bring about more accurate log D calculations and encourage species-specific QSAR involving log DN and log DI. This work also brings attention to the fascinating world of nature’s highly stabilized ion pairs. PMID:19265385

Automated potentiometric titrations in KCl/water-saturated octanol: method for quantifying factors influencing ion-pair partitioning.

Science.gov (United States)

Scherrer, Robert A; Donovan, Stephen F

2009-04-01

The knowledge base of factors influencing ion pair partitioning is very sparse, primarily because of the difficulty in determining accurate log P(I) values of desirable low molecular weight (MW) reference compounds. We have developed a potentiometric titration procedure in KCl/water-saturated octanol that provides a link to log P(I) through the thermodynamic cycle of ionization and partitioning. These titrations have the advantage of being independent of the magnitude of log P, while maintaining a reproducibility of a few hundredths of a log P in the calculated difference between log P neutral and log P ion pair (diff (log P(N - I))). Simple model compounds can be used. The titration procedure is described in detail, along with a program for calculating pK(a)'' values incorporating the ionization of water in octanol. Hydrogen bonding and steric factors have a greater influence on ion pairs than they do on neutral species, yet these factors are missing from current programs used to calculate log P(I) and log D. In contrast to the common assumption that diff (log P(N - I)) is the same for all amines, they can actually vary more than 3 log units, as in our examples. A major factor affecting log P(I) is the ability of water and the counterion to approach the charge center. Bulky substituents near the charge center have a negative influence on log P(I). On the other hand, hydrogen bonding groups near the charge center have the opposite effect by lowering the free energy of the ion pair. The use of this titration method to determine substituent ion pair stabilization values (IPS) should bring about more accurate log D calculations and encourage species-specific QSAR involving log D(N) and log D(I). This work also brings attention to the fascinating world of nature's highly stabilized ion pairs.

Isothermal Titration Calorimetry in the Student Laboratory

Science.gov (United States)

Wadso, Lars; Li, Yujing; Li, Xi

2011-01-01

Isothermal titration calorimetry (ITC) is the measurement of the heat produced by the stepwise addition of one substance to another. It is a common experimental technique, for example, in pharmaceutical science, to measure equilibrium constants and reaction enthalpies. We describe a stirring device and an injection pump that can be used with a…

Using Spreadsheets to Produce Acid-Base Titration Curves.

Science.gov (United States)

Cawley, Martin James; Parkinson, John

1995-01-01

Describes two spreadsheets for producing acid-base titration curves, one uses relatively simple cell formulae that can be written into the spreadsheet by inexperienced students and the second uses more complex formulae that are best written by the teacher. (JRH)

Studies of factors affecting uranium determinations by automated coulometric titration (New Brunswick Laboratory/Davies--Gray Method)

International Nuclear Information System (INIS)

Harrar, J.E.; Boyle, W.G.

1976-01-01

The method's errors are defined to ascertain its absolute accuracy. An analytical technique was developed to examine vanadyl sulfate diluent for vanadium (V). None could be found in any of the lots tested. Certain lots of reagent-grade phosphoric acid contained an unidentified impurity that caused high generator-electrode potentials and a positive error. The current-potential characteristics of the generator electrode were measured. The data indicated that a significant fraction of uranium (IV) was oxidized directly during the early stages of titration. Using equations theoretically applicable to such a titration, a negligible difference was found between the inflection point of the titration curve and the equivalence point in the titration. However, the actual experimental curves did not agree with the theoretical curves early in the titration. Measurements of the background current indicated a level equivalent to approximately 0.2 mg uranium. The evaluation of the reagent delivery system used in the automated analyzer revealed adequate reproducibility. 8 tables

Thermodynamic signatures of fragment binding: Validation of direct versus displacement ITC titrations.

Science.gov (United States)

Rühmann, Eggert; Betz, Michael; Fricke, Marie; Heine, Andreas; Schäfer, Martina; Klebe, Gerhard

2015-04-01

Detailed characterization of the thermodynamic signature of weak binding fragments to proteins is essential to support the decision making process which fragments to take further for the hit-to-lead optimization. Isothermal titration calorimetry (ITC) is the method of choice to record thermodynamic data, however, weak binding ligands such as fragments require the development of meaningful and reliable measuring protocols as usually sigmoidal titration curves are hardly possible to record due to limited solubility. Fragments can be titrated either directly under low c-value conditions (no sigmoidal curve) or indirectly by use of a strong binding ligand displacing the pre-incubated weak fragment from the protein. The determination of Gibbs free energy is reliable and rather independent of the applied titration protocol. Even though the displacement method achieves higher accuracy, the obtained enthalpy-entropy profile depends on the properties of the used displacement ligand. The relative enthalpy differences across different displacement experiments reveal a constant signature and can serve as a thermodynamic fingerprint for fragments. Low c-value titrations are only reliable if the final concentration of the fragment in the sample cell exceeds 2-10 fold its K(D) value. Limited solubility often prevents this strategy. The present study suggests an applicable protocol to characterize the thermodynamic signature of protein-fragment binding. It shows however, that such measurements are limited by protein and fragment solubility. Deviating profiles obtained by use of different displacement ligands indicate that changes in the solvation pattern and protein dynamics most likely take influence on the resulting overall binding signature. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of uranium by a gravimetric-volumetric titration method

International Nuclear Information System (INIS)

Krtil, J.

1998-01-01

A volumetric-gravimetric modification of a method for the determination of uranium based on the reduction of uranium to U (IV) in a phosphoric acid medium and titration with a standard potassium dichromate solution is described. More than 99% of the stoichiometric amount of the titrating solution is weighed and the remainder is added volumetrically by using the Mettler DL 40 RC Memotitrator. Computer interconnected with analytical balances collects continually the data on the analyzed samples and evaluates the results of determination. The method allows to determine uranium in samples of uranium metal, alloys, oxides, and ammonium diuranate by using aliquot portions containing 30 - 100 mg of uranium with the error of determination, expressed as the relative standard deviation, of 0.02 - 0.05%. (author)

Thermometric titration of acids in pyridine.

Science.gov (United States)

Vidal, R; Mukherjee, L M

1974-04-01

Thermometric titration of HClO(4), HI, HNO(3), HBr, picric acid o-nitrobenzoic acid, 2,4- and 2,5-dinitrophenol, acetic acid and benzoic acid have been attempted in pyridine as solvent, using 1,3-diphenylguanidine as the base. Except in the case of 2,5-dinitrophenol, acetic acid and benzoic acid, the results are, in general, reasonably satisfactory. The approximate molar heats of neutralization have been calculated.

Determination of nitric acid in highly radioactive solutions by the method of coulometric titration

International Nuclear Information System (INIS)

Gromov, V.S.; Kuperman, A.Ya.; Smirnov, Yu.A.

1988-01-01

A procedure, a cell, and an electronic block have been developed for a long-distance determination of nitric acid in highly radioactive industrial solutions by coulometric titration under hot chamber conditions. A solution of a mixture of ammonium and potassium oxalates was used for the background and anoide electrolytes. This solution prevents the hydrolysis of the metal ions and appreciably decreases the rate of accumulation of the acid in the anode chamber of the cell. Titration with 0.1-0.5 A currents is carried out with internal generation of hydroxyl ions. The cell was prepared from a radiation-resistant and transparent material, poly(methyl methacrylate). The anode and cathode chambers were separated by a cellophane membrane, reinforced by a porous glass filter. By using the electronic coulometric block working together with a pH-meter (EV-74 or I-130) and with an automatic titration block (BAT-15), the titration can be carried out automatically, and the determination results can be obtained in a digital form

Accurate and precise determination of 2-25mg amounts of uranium by means of a special automatic potentiometric titration

International Nuclear Information System (INIS)

Slanina, J.; Bakker, F.; Groen, A.J.P.; Lingerak, W.A.

1978-01-01

A precise and accurate potentiometric titration of 2-25 mg of uranium is described. The uranium is reduced to U(IV) according to the method of Eberle et al. [3], and titrated with 0.05 N potassium dichromate, using a platinum indicator electrode. During the sample preparation the walls of the titration vessel are cleaned by centrifugation. To avoid overshoot of the set point a special differentiator is described, that interrupts the titration until equilibrium is reached. The precision of the method is 0.02%, the accuracy is better than 0.04% rel. Each titration takes 5 min. (orig.) [de

A Titration Technique for Demonstrating a Magma Replenishment Model.

Science.gov (United States)

Hodder, A. P. W.

1983-01-01

Conductiometric titrations can be used to simulate subduction-setting volcanism. Suggestions are made as to the use of this technique in teaching volcanic mechanisms and geochemical indications of tectonic settings. (JN)

Linear titration plot for the determination of boron in the primary coolant of a pressurized water reactor

International Nuclear Information System (INIS)

Midgley, D.; Gatford, C.

1992-01-01

A linear titration plot method has been devised for the determination of boron as boric acid in partly neutralized solution, such as occurs in the primary coolant of pressurized water reactors. The total boron and the alkali in the sample are determined simultaneously. Although it is not essential to add mannitol in this method, it is more accurate when the solution is saturated with mannitol. Comparisons are made with other modes of titration: Gran plots, first and second differential potentiometric titrations and indicator titrations. None of these gives the total boron directly in partly neutralized solutions. (author)

Thermodynamic analysis of Bacillus subtilis endospore protonation using isothermal titration calorimetry

Science.gov (United States)

Harrold, Zoë R.; Gorman-Lewis, Drew

2013-05-01

Bacterial proton and metal adsorption reactions have the capacity to affect metal speciation and transport in aqueous environments. We coupled potentiometric titration and isothermal titration calorimetry (ITC) analyses to study Bacillus subtilis spore-proton adsorption. We modeled the potentiometric data using a four and five-site non-electrostatic surface complexation model (NE-SCM). Heats of spore surface protonation from coupled ITC analyses were used to determine site specific enthalpies of protonation based on NE-SCMs. The five-site model resulted in a substantially better model fit for the heats of protonation but did not significantly improve the potentiometric titration model fit. The improvement observed in the five-site protonation heat model suggests the presence of a highly exothermic protonation reaction circa pH 7 that cannot be resolved in the less sensitive potentiometric data. From the log Ks and enthalpies we calculated corresponding site specific entropies. Log Ks and site concentrations describing spore surface protonation are statistically equivalent to B. subtilis cell surface protonation constants. Spore surface protonation enthalpies, however, are more exothermic relative to cell based adsorption suggesting a different bonding environment. The thermodynamic parameters defined in this study provide insight on molecular scale spore-surface protonation reactions. Coupled ITC and potentiometric titrations can reveal highly exothermic, and possibly endothermic, adsorption reactions that are overshadowed in potentiometric models alone. Spore-proton adsorption NE-SCMs derived in this study provide a framework for future metal adsorption studies.

Microchemical analysis of materials based on Y-Ba-Cu by spectrophotometric titration

International Nuclear Information System (INIS)

Kuznetsov, V.V.; Samorukova, O.L.; Zakharov, Eh.K.

1990-01-01

A complex method for analysis of superconductor and similar materials on Y-Ba-Cu basis has been developed, which comprises yttrium and copper determination by their indicator spectrophotometric titration by EDTA and/or complexone 4 in the presence of arsenazo 3. The use of complexone 4 is more favourable. Titration is carried out at λ=650 nm. The method has a sufficient accuracy, provides for rapid determination and does not reguire preliminary separation of components

Molecular Weight Measurement of Biobased Furan Polyamides via Non-Aqueous Potentiometric Titration

Science.gov (United States)

2013-06-01

electromagnetic fields, all titrations were completed in a chemical hood, which acted as a Faraday cage (a shield used to blocks external static and...while using DMF as a solvent. Additionally, no Faraday cage was used in the experimental setup, so the titrations were conducted inside the chemical...monomer was becoming more soluble in glacial acetic acid and the amount of chlorobenzene had less of an effect on the solution properties (i.e

[Acids in coffee. XI. The proportion of individual acids in the total titratable acid].

Science.gov (United States)

Engelhardt, U H; Maier, H G

1985-07-01

22 acids in ground roast coffees and instant coffees were determined by GLC of their silyl derivatives (after preseparation by gel electrophoresis) or isotachophoresis. The contribution to the total acidity (which was estimated by titration to pH 8 after cation exchange of the coffee solutions) was calculated for each individual acid. The mentioned acids contribute with 67% (roast coffee) and 72% (instant coffee) to the total acidity. In the first place citric acid (12.2% in roast coffee/10.7% in instant coffee), acetic acid (11.2%/8.8%) and the high molecular weight acids (8%/9%) contribute to the total acidity. Also to be mentioned are the shares of chlorogenic acids (9%/4.8%), formic acid (5.3%/4.6%), quinic acid (4.7%/5.9%), malic acid (3.9%/3%) and phosphoric acid (2.5%/5.2%). A notable difference in the contribution to total acidity between roast and instant coffee was found for phosphoric acid and pyrrolidonecarboxylic acid (0.7%/1.9%). It can be concluded that those two acids are formed or released from e.g. their esters in higher amounts than other acids during the production of instant coffee.

Concurrent determination of total serum calcium and magnesium by thermometric titration with ethylenediaminetetraacetate.

Science.gov (United States)

Callicott, R H; Carr, P W

1976-07-01

Total serum calcium and magnesium may be determined in one thermometric titration, with disodium ethylenediaminetetraacetate as the titrant. A 1-ml serum sample is diluted with 1 ml of tris(hydroxymethyl)aminomethane buffer (pH 8) and titrated at a constant rate with a motorized syringe buret. Results by the thermometric method compared well with those by atomic absorption spectroscopy.

Measuring titratable alkalinity by single versus double endpoint titration: An evaluation in two cyprinodont species and implications for characterizing net H+ flux in aquatic organisms.

Science.gov (United States)

Brix, Kevin V; Wood, Chris M; Grosell, Martin

2013-01-01

In this study, Na(+) uptake and acid-base balance in the euryhaline pupfish Cyprinodon variegatus variegatus were characterized when fish were exposed to pH 4.5 freshwater (7mM Na(+)). Similar to the related cyprinodont, Fundulus heteroclitus, Na(+) uptake was significantly inhibited when exposed to low pH water. However, it initially appeared that C. v. variegatus increased apparent net acid excretion at low pH relative to circumneutral pH. This result is opposite to previous observations for F. heteroclitus under similar conditions where fish were observed to switch from apparent net H(+) excretion at circumneutral pH to apparent net H(+) uptake at low pH. Further investigation revealed disparate observations between these studies were the result of using double endpoint titrations to measure titratable alkalinity fluxes in the current study, while the earlier study utilized single endpoint titrations to measure these fluxes (i.e.,. Cyprinodon acid-base transport is qualitatively similar to Fundulus when characterized using single endpoint titrations). This led to a comparative investigation of these two methods. We hypothesized that either the single endpoint methodology was being influenced by a change in the buffer capacity of the water (e.g., mucus being released by the fish) at low pH, or the double endpoint methodology was not properly accounting for ammonia flux by the fish. A series of follow-up experiments indicated that buffer capacity of the water did not change significantly, that excretion of protein (a surrogate for mucus) was actually reduced at low pH, and that the double endpoint methodology does not properly account for NH(3) excretion by fish under low pH conditions. As a result, it overestimates net H(+) excretion during low pH exposure. After applying the maximum possible correction for this error (i.e., assuming that all ammonia is excreted as NH(3)), the double endpoint methodology indicates that net H(+) transport was reduced to

Group Contribution Based Process Flowsheet Synthesis, Design and Modelling

DEFF Research Database (Denmark)

d'Anterroches, Loïc; Gani, Rafiqul

2004-01-01

This paper presents a process-group-contribution Method to model. simulate and synthesize a flowsheet. The process-group based representation of a flowsheet together with a process "property" model are presented. The process-group based synthesis method is developed on the basis of the computer...... aided molecular design methods and gives the ability to screen numerous process alternatives without the need to use the rigorous process simulation models. The process "property" model calculates the design targets for the generated flowsheet alternatives while a reverse modelling method (also...... developed) determines the design variables matching the target. A simple illustrative example highlighting the main features of the methodology is also presented....

Amperometric titration of thorium and some lanthanoids in acetic-acid medium using two indicator electrodes

International Nuclear Information System (INIS)

Khadeev, V.A.; Gevorgyan, A.M.; Talipov, Sh.T.; Kostylev, V.S.

1979-01-01

The votammetric behaviour of nitriletrimethylphosphonic acid (NTMP) in the medium of anhydrous acetic acid with different backgrounds in the anode region of polarization of a platinum microdisk electrode, is studied. The optimal conditions are found for the amperometric titration with two indicator electrodes of thorium and same lanthanides by a NTMP solution in anhydrous acetic medium. The influence of foreign anions and cations on the results of titration by the NTPM solution in anhydrous acetic acid is studied. The selectivity of titration in anhydrous medium is higher than in aqueous

Group contribution modelling for the prediction of safety-related and environmental properties

DEFF Research Database (Denmark)

Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

warming potential and ozone depletion potential. Process safety studies and environmental assessments rely on accurate property data. Safety data such as flammability limits, heat of combustion or auto ignition temperature play an important role in quantifying the risk of fire and explosions among others......We present a new set of property prediction models based on group contributions to predict major safety-related and environmental properties for organic compounds. The predicted list of properties includes lower and upper flammability limits, heat of combustion, auto ignition temperature, global...... models like group contribution (GC) models can estimate data. However, the estimation needs to be accurate, reliable and as little time-consuming as possible so that the models can be used on the fly. In this study the Marrero and Gani group contribution (MR GC) method has been used to develop the models...

Potentiometric titration of zinc and cadmium in electrolytes of in galvanic baths

International Nuclear Information System (INIS)

Kosyuga, E.A.; Kalugin, A.A.; Gur'ev, I.A.

1979-01-01

The method of potentiometric titration of zinc and cadmium by complexone 3 in electrolytes of galvanic baths using sulphide - silver electrode for determining the finite point of titration is suggested. Copper (2) ions are proposed as indicator ions. The potentiometric determination should be performed at pH=10. The method is verified on model electrolyte solutions and on the electrolyte solutions of operating baths.The technique can be used for automatic control. The time for analysis is 10 minutes

Titration of thorium and rare earths with ethylenediaminetetraacetic acid using semimethylthymol blue by visual end-point indication

International Nuclear Information System (INIS)

Hafez, M.A.H.; Kenawy, I.M.M.; Ramadan, M.A.M.

1994-01-01

The precision and accuracy attainable in direct complexometric titrations of Thsup(4+) consecutively with either lighter (La 3+ , Nd 3+ , Sm 3+ , Eu 3+ or Gd 3+ ) or heavier lanthanides (Dy 3+ ) in different proportions using Semimethylthymol Blue (SMTB) as a metallochromic indicator and disodium dihydrogen ethylenediaminetetraacetate were studied. Thorium (IV) was titrated at pH 2, the Ph was adjusted to 5.5-6.0 by adding hexamethylenetetramine (hexamine) buffer and acetylacetone-acetone solution and La 3+ (or Nd 3+ , Sm 3+ , Eu 3+ , Gd 3+ or Dy 3+ ) was then titrated. A comparison of the indicators SMTB and Methylthymol Blue (MTB) for successive titrations of Th 4+ and any of the rare earth ions was carried out. The proposed titration method was applied successfully to some naturally occurring ores and minerals containing thorium and some lanthanides and the results were satisfactory. (Author)

A new titration system of a novel split-type superconducting magnet NMR spectrometer.

Science.gov (United States)

Kitagawa, Isao; Tanaka, Hideki; Okada, Michiya; Kitaguchi, Hitoshi; Kohzuma, Takamitsu

2008-12-01

A new titration system for studying protein-ligand interactions has been developed. In this system, the sample solution is circulated in the route formed by an access path in a split superconducting magnet to maintain a constant protein concentration during the titration experiments. A concentration-control procedure for the ligand/protein ratio is devised, and the ligand/protein ratio is well controlled by this apparatus.

Application of cause-and-effect analysis to potentiometric titration.

Science.gov (United States)

Kufelnicki, A; Lis, S; Meinrath, G

2005-08-01

A first attempt has been made to interpret physicochemical data from potentiometric titration analysis in accordance with the complete measurement-uncertainty budget approach (bottom-up) of ISO and Eurachem. A cause-and-effect diagram is established and discussed. Titration data for arsenazo III are used as a basis for this discussion. The commercial software Superquad is used and applied within a computer-intensive resampling framework. The cause-and-effect diagram is applied to evaluation of seven protonation constants of arsenazo III in the pH range 2-10.7. The data interpretation is based on empirical probability distributions and their analysis by second-order correct confidence estimates. The evaluated data are applied in the calculation of a speciation diagram including uncertainty estimates using the probabilistic speciation software Ljungskile.

Catalytic thermometric titrations in non-aqueous solvents by coulometrically generated titrant.

Science.gov (United States)

Vajgand, V J; Gaál, F F; Brusin, S S

1970-05-01

Catalytic thermometric titrations have been developed for tertiary amines and salts of organic acids in acetic and propionic anhydride with titrant coulometrically generated at a mercury and/or platinum anode, hydroquinone being added to the solution titrated if the platinum anode is used. The results obtained are compared with those obtained by coulometric titration with the end-point detected either photometrically or potentiometrically. On a élaboré des titrages thermométriques catalytiques pour les amines tertiaires et les sels d'acides organiques en anhydrides aétique et propionique avec l'agent de titrage engendré coulométriquement sur une anode de mercure et/ou platine, de l'hydroquinone étant ajoutée à la solution titrée si l'on emploie l'anode de platine. Les résultats obtenus sont comparés avec ceux obtenus par titrage coulométrique avec le point de fin de réaction détecté soit photométriquement soit potentioétriquement.

A comparison of cationic polymerization and esterification for end-point detection in the catalytic thermometric titration of organic bases.

Science.gov (United States)

J Greenhow, E; Viñas, P

1984-08-01

A systematic comparison has been made of two indicator systems for the non-aqueous catalytic thermometric titration of strong and weak organic bases. The indicator reagents, alpha-methylstyrene and mixtures of acetic anhydride and hydroxy compounds, are shown to give results (for 14 representative bases) which do not diner significantly in coefficient of variation or titration error. Calibration graphs for all the samples, in the range 0.01-0.1 meq, are linear, with correlation coefficients of 0.995 or better. Aniline, benzylamine, n-butylamine, morpholine, pyrrole, l-dopa, alpha-methyl-l-dopa, dl-alpha-alanine, dl-leucine and l-cysteine cannot be determined when acetic anhydride is present in the sample solution, but some primary and second amines can. This is explained in terms of rates of acetylation of the amino groups.

Axitinib dose titration: analyses of exposure, blood pressure and clinical response from a randomized phase II study in metastatic renal cell carcinoma.

Science.gov (United States)

Rini, B I; Melichar, B; Fishman, M N; Oya, M; Pithavala, Y K; Chen, Y; Bair, A H; Grünwald, V

2015-07-01

In a randomized, double-blind phase II trial in patients with metastatic renal cell carcinoma (mRCC), axitinib versus placebo titration yielded a significantly higher objective response rate. We evaluated pharmacokinetic and blood pressure (BP) data from this study to elucidate relationships among axitinib exposure, BP change, and efficacy. Patients received axitinib 5 mg twice daily during a lead-in period. Patients who met dose-titration criteria were randomized 1:1 to stepwise dose increases with axitinib or placebo. Patients ineligible for randomization continued without dose increases. Serial 6-h and sparse pharmacokinetic sampling were carried out; BP was measured at clinic visits and at home in all patients, and by 24-h ambulatory BP monitoring (ABPM) in a subset of patients. Area under the plasma concentration-time curve from 0 to 24 h throughout the course of treatment (AUCstudy) was higher in patients with complete or partial responses than those with stable or progressive disease in the axitinib-titration arm, but comparable between these groups in the placebo-titration and nonrandomized arms. In the overall population, AUCstudy and efficacy outcomes were not strongly correlated. Mean BP across the population was similar when measured in clinic, at home, or by 24-h ABPM. Weak correlations were observed between axitinib steady-state exposure and diastolic BP. When grouped by change in diastolic BP from baseline, patients in the ≥10 and ≥15 mmHg groups had longer progression-free survival. Optimal axitinib exposure may differ among patients with mRCC. Pharmacokinetic or BP measurements cannot be used exclusively to guide axitinib dosing. Individualization of treatment with vascular endothelial growth factor receptor tyrosine kinase inhibitors, including axitinib, is thus more complex than anticipated and cannot be limited to a single clinical factor. © The Author 2015. Published by Oxford University Press on behalf of the European Society for Medical

Estimation of Physical Properties of Amino Acids by Group-Contribution Method

DEFF Research Database (Denmark)

Jhamb, Spardha Virendra; Liang, Xiaodong; Gani, Rafiqul

2018-01-01

In this paper, we present group-contribution (GC) based property models for estimation of physical properties of amino acids using their molecular structural information. The physical properties modelled in this work are normal melting point (Tm), aqueous solubility (Ws), and octanol....../water partition coefficient (Kow) of amino acids. The developed GC-models are based on the published GC-method by Marrero and Gani (J. Marrero, R. Gani, Fluid Phase Equilib. 2001, 183-184, 183-208) with inclusion of new structural parameters (groups and molecular weight of compounds). The main objective...... of introducing these new structural parameters in the GC-model is to provide additional structural information for amino acids having large and complex structures and thereby improve predictions of physical properties of amino acids. The group-contribution values were calculated by regression analysis using...

Isothermal Titration Calorimetry Can Provide Critical Thinking Opportunities

Science.gov (United States)

Moore, Dale E.; Goode, David R.; Seney, Caryn S.; Boatwright, Jennifer M.

2016-01-01

College chemistry faculties might not have considered including isothermal titration calorimetry (ITC) in their majors' curriculum because experimental data from this instrumental method are often analyzed via automation (software). However, the software-based data analysis can be replaced with a spreadsheet-based analysis that is readily…

Determination of arsenate and organic arsenic via potentiometric titration of its heteropoly anions.

Science.gov (United States)

Metelka, R; Slavíková, S; Vytras, K

2002-08-16

Determination of arsenate based on its conversion to molybdoarsenate heteropoly anions followed by potentiometric titration is described. The titration is realized on the ion-pairing principle using cetylpyridinium chloride (or an analogous titrant containing a lipophilic cation), and is monitored by a carbon paste electrode, although other liquid-polymeric membrane-based electrodes can also be used. Calibration plots of the titrant end-point consumption versus concentration of arsenic were constructed and used to evaluate the content of arsenic in aqueous samples. The method could be applied in the analyses of samples with quite low arsenic content (amounts approximately 10 mug As in 50 cm(3) could be titrated). Organic arsenic was determined analogously after the Schöniger combustion of the sample and conversion of its arsenic to arsenate.

A randomized primary care trial of steroid titration against mannitol in persistent asthma: STAMINA trial.

Science.gov (United States)

Lipworth, Brian J; Short, Philip M; Williamson, Peter A; Clearie, Karine L; Fardon, Thomas C; Jackson, Cathy M

2012-03-01

We compared titrating inhaled corticosteroid (ICS) against mannitol airway hyperresponsiveness (AHR) or a reference strategy (control) based on symptoms, reliever use, and lung function in primary care. One hundred sixty-four patients with persistent asthma were randomized in parallel group fashion following an initial ICS tapering. Subsequent ICS doses (as ciclesonide) were titrated against either the provocative dose of mannitol causing a 10% fall in FEV(1) (PD(10)) (AHR strategy) or a control group (reference strategy) over a 1-year period. One hundred nineteen participants (n = 61 AHR, n = 58 control) completed the study. Time to first mild exacerbation was not significantly different: hazard ratio, 1.29; 95% CI, 0.716-2.31; P = .40. Although there were 27% fewer total number of mild exacerbations over 12 months in AHR vs control groups (n = 84 vs n = 115, P = .03), there was no difference in severe exacerbations (n = 12 vs n = 13). No other significant differences were seen between groups with the exception of mannitol PD(10) and ICS dose. There was a 1.52 (95% CI, 0.61-2.42; P = .001) doubling dose difference in mannitol PD(10) between AHR vs control groups. The final mean daily ciclesonide dose was higher (P < .0001) in AHR vs control groups (514 μg vs 208 μg), with no associated significant suppression of overnight urinary cortisol/creatinine. Significant improvements were seen within the AHR group but not the control group for the provocative concentration of methacholine causing a 20% fall in FEV(1) (P < .05), salivary eosinophilic cationic protein (P < .05), exhaled nitric oxide (P < .05), symptoms (P < .005), and reliever use (P < .001). Mannitol challenge was well tolerated in a primary care setting. Using mannitol resulted in exposure to a higher dose of ciclesonide, which was associated with equivocal effects on exacerbations without associated adrenal suppression. Large-scale trials using mannitol in patients with more severe disease may now be

Trace analysis of acids and bases by conductometric titration with multiparametric non-linear regression.

Science.gov (United States)

Coelho, Lúcia H G; Gutz, Ivano G R

2006-03-15

A chemometric method for analysis of conductometric titration data was introduced to extend its applicability to lower concentrations and more complex acid-base systems. Auxiliary pH measurements were made during the titration to assist the calculation of the distribution of protonable species on base of known or guessed equilibrium constants. Conductivity values of each ionized or ionizable species possibly present in the sample were introduced in a general equation where the only unknown parameters were the total concentrations of (conjugated) bases and of strong electrolytes not involved in acid-base equilibria. All these concentrations were adjusted by a multiparametric nonlinear regression (NLR) method, based on the Levenberg-Marquardt algorithm. This first conductometric titration method with NLR analysis (CT-NLR) was successfully applied to simulated conductometric titration data and to synthetic samples with multiple components at concentrations as low as those found in rainwater (approximately 10 micromol L(-1)). It was possible to resolve and quantify mixtures containing a strong acid, formic acid, acetic acid, ammonium ion, bicarbonate and inert electrolyte with accuracy of 5% or better.

Coulometric thermometric titration of halides in molten calcium nitrate tetrahydrate.

Science.gov (United States)

Zsigrai, I J; Bartusz, D B

1983-01-01

A method for coulometric thermometric precipitation titrations of chloride, bromide and iodide in molten calcium nitrate tetrahydrate at 55 degrees with coulometrically generated silver ions has been developed. The change in temperature during the titration is followed with the aid of a thermistor bridge coupled to a recorder. To minimize the temperature effect of the passage of current through the melt, two thermistors are connected in opposition in the bridge, with one in the anodic and the other in the cathodic cell compartment. Amounts of 62-80 mumole of halide have been determined with relative error below 0.4% and relative standard deviation less than 2.7%. The relative error in determination of 40 mumole of iodide was + 2%.

Oxygen titration in sodium. The mercury method and its use for very low values

International Nuclear Information System (INIS)

Champeix, L.; Darras, R.; Duflo, J.

1958-01-01

The mercury method for the oxygen titration in sodium has now been known for ten years and is probably the more frequently used. In this text, precision are given to what extent it is valuable when used in microanalysis. Details are given on the apparatus, its manipulation and its calibration. After testing, we have decided to use flame spectroscopy to titrate the sodium hydroxide formed. Discussions are exposed on the errors due to the presence of sodium chloride and calcium. Results are examined from the point of view of their reproducibility and accuracy. If great care is taken, this method allows oxygen titration in sodium even for values below 10 ppm with satisfactory precision. (author) [fr

1H NMR study of effects of synergistic anion and metal ion binding on pH titration of the histidinyl side-chain residues of the half-molecules of ovotransferrin

International Nuclear Information System (INIS)

Woodworth, R.C.; Butcher, N.D.; Brown, S.A.; Brown-Mason, A.

1987-01-01

Separation of ovotransferrin into C-terminal (OTf/2C) and N-terminal (OTf/2N) half-molecules has made possible the resolution of all expected histidinyl C(2)H resonances by proton nuclear magnetic resonance at 250 MHz. The chemical shift of many of the resonances decreases with increasing pH, allowing construction of titration curves, whereas a few resonances fail to titrate. On formation of the Ga/sup III/OTf/2(C 2 O 4 ) ternary complexes, two of the low-field C(2)H resonances in each half-molecule fail to titrate. This behavior implicates the imidazole groups giving rise to these resonances as ligands to the bound metal ion. A third C(2)H resonance in each half-molecule undergoes a marked reduction in pK'/sub a/ on formation of the ternary complex. The imidazole group displaying this resonance is implicated in a proton-relay scheme involved in binding the synergistic anion, oxalate, and a water of hydration on the bound metal ion. The titration curves for the various imidazole resonances have been fit to a four-parameter equation involving estimation of the pK'/sub a/, the limiting chemical shift values, and a Hill constant n. Hill constants of 1, which suggests positive cooperativity in the titration of this residue. The basis for this behavior cannot be rationalized at this time. 13 C NMR studies of [zeta- 13 C]Arg-OTf suggest the Arg side chains may not be intimately involved in formation of the ternary complex

[Research on determination of chemical purity of andrographolide by coulometric titration method].

Science.gov (United States)

Yang, Ning; Yang, Dezhi; Xu, Lishen; Lv, Yang

2010-04-01

The determination of chemical purity of andrographolide by coulometric titration method is studied in this paper. The coulometric titration was carried out in a mixture composed of 4 mol x L(-1) hydrochloric acid and 1 mol x L(-1) potassium bromide solution and 1 mol x L(-1) potassium nitrate solution (1:1). Bromine is electrogenerated at the anode and reacts with the andrographolide. The number of electrons involved in the eleatrode reaction is 2. Purity of andrographolide is 99.76% compared with 99.77% utilizing area normalization method by HPLC. The RSD are 0.33% and 0.02% respectively. The results from two methods are consistent, so the determination of chemical purity of andrographolide by coulometric titration method is scientific and feasible. The method is rapid, simple, convenient, sensitive and accurate. The reference material is not essential in the method. The method is suitable for determination of chemical purity of andrographolide.

Spectroscopic study on variations in illite surface properties after acid-base titration.

Science.gov (United States)

Liu, Wen-xin; Coveney, R M; Tang, Hong-xiao

2003-07-01

FT-IR, Raman microscopy, XRD, 29Si and 27Al MAS NMR, were used to investigate changes in surface properties of a natural illite sample after acid-base potentiometric titration. The characteristic XRD lines indicated the presence of surface Al-Si complexes, preferable to Al(OH)3 precipitates. In the microscopic Raman spectra, the vibration peaks of Si-O and Al-O bonds diminished as a result of treatment with acid, then increased after hydroxide back titration. The varied ratio of signal intensity between (IV)Al and (VI)Al species in 27Al MAS NMR spectra, together with the stable BET surface area after acidimetric titration, suggested that edge faces and basal planes in the layer structure of illite participated in dissolution of structural components. The combined spectroscopic evidence demonstrated that the reactions between illite surfaces and acid-leaching silicic acid and aluminum ions should be considered in the model description of surface acid-base properties of the aqueous illite.

pH-metric solubility. 3. Dissolution titration template method for solubility determination.

Science.gov (United States)

Avdeef, A; Berger, C M

2001-12-01

The main objective of this study was to develop an effective potentiometric saturation titration protocol for determining the aqueous intrinsic solubility and the solubility-pH profile of ionizable molecules, with the specific aim of overcoming incomplete dissolution conditions, while attempting to shorten the data collection time. A modern theory of dissolution kinetics (an extension of the Noyes-Whitney approach) was applied to acid-base titration experiments. A thermodynamic method was developed, based on a three-component model, to calculate interfacial, diffusion-layer, and bulk-water reactant concentrations in saturated solutions of ionizable compounds perturbed by additions of acid/base titrant, leading to partial dissolution of the solid material. Ten commercial drugs (cimetidine, diltiazem hydrochloride, enalapril maleate, metoprolol tartrate, nadolol, propoxyphene hydrochloride, quinine hydrochloride, terfenadine, trovafloxacin mesylate, and benzoic acid) were chosen to illustrate the new titration methodology. It was shown that the new method is about 10 times faster in determining equilibrium solubility constants, compared to the traditional saturation shake-flask methods.

A Computer-Based Simulation of an Acid-Base Titration

Science.gov (United States)

Boblick, John M.

1971-01-01

Reviews the advantages of computer simulated environments for experiments, referring in particular to acid-base titrations. Includes pre-lab instructions and a sample computer printout of a student's use of an acid-base simulation. Ten references. (PR)

Determination of sulfur compounds in hydrotreated transformer base oil by potentiometric titration.

Science.gov (United States)

Chao, Qiu; Sheng, Han; Cheng, Xingguo; Ren, Tianhui

2005-06-01

A method was developed to analyze the distribution of sulfur compounds in model sulfur compounds by potentiometric titration, and applied to analyze hydrotreated transformer base oil. Model thioethers were oxidized to corresponding sulfoxides by tetrabutylammonium periodate and sodium metaperiodate, respectively, and the sulfoxides were titrated by perchloric acid titrant in acetic anhydride. The contents of aliphatic thioethers and total thioethers were then determined from that of sulfoxides in solution. The method was applied to determine the organic sulfur compounds in hydrotreated transformer base oil.

Interlaboratory comparison exercise for the determination of uranium by potentiometric titration (first phase)

International Nuclear Information System (INIS)

Verdingh, V.; Le Duigou, Y.

1991-01-01

Upon request of the Esarda working group on low-enriched uranium conversion and fuel fabrication plants an interlaboratory comparison was organized, to assess the precision and accuracy concerning the determination of uranium by the potentiometric titration method. This report presents the results of the first phase of this exercise (pure uranyl-nitrate solutions). The solutions used in this intercomparison have been certified for their uranium content by the CBNM, Geel. Comparison of the laboratory results with the certified values shows excellent, good and fairly good agreement for many of the participating laboratories. 10 tabs., 5 figs., 10 refs

Comparing the Titrations of Mixed-Acid Solutions Using Dropwise and Constant-Flow Techniques

Science.gov (United States)

Charlesworth, Paul; Seguin, Matthew J.; Chesney, David J.

2003-11-01

A mixed-acid solution containing hydrochloric and phosphoric acids was used to determine the error associated with performing a real-time titration. The results were compared against those obtained by performing the titration in a more traditional dropwise addition of titrant near the equivalence points. It was found that the real-time techniques resulted in significantly decreased analysis times while maintaining a low experimental error. The constant-flow techniques were implemented into two different levels of chemistry. It was found that students could successfully utilize the modified experiments. Problems associated with the techniques, major sources of error, and their solutions are discussed. In both cases, the use of the constant-flow setup has increased student recollection of key concepts, such as pKa determination, proper indicator choice, and recognizing the shape of specific titration curves by increasing student interest in the experiment.

Rapid determination of the equivalence volume in potentiometric acid-base titrations to a preset pH-I Theory and applications.

Science.gov (United States)

Ivaska, A

1974-06-01

A new approach to shorten the time needed for an acid-base titration has been made. The method developed is based on the equation for acid-base titrations derived by Ingman and Still. The equation is transformed into such a form that only one titration point is needed to calculate the equivalence volume when the titration is carried out to a preset pH which can be chosen according to the experimental conditions. The method is used for titration of acetic acid, log K(H)(HA) = 4.65, hydroxylammonium ion, log K(H)(HA) approximately 6.2, and boric acid, log K(H)(HA) approximately 9.1, with an error of 0.1-0.5%. In titration of hydrogen ascorbate ion, log K(H)(HA) approximately 11.3, the error obtained was about 0.3-2%.

Application of the Group Contribution Approach to Nafion Swelling

Czech Academy of Sciences Publication Activity Database

Randová, A.; Bartovská, L.; Hovorka, Š.; Poloncarzová, M.; Kolská, Z.; Izák, Pavel

2009-01-01

Roč. 111, č. 4 (2009), s. 1745-1750 ISSN 0021-8995 R&D Projects: GA ČR GA104/08/0600; GA AV ČR IAA400720710 Institutional research plan: CEZ:AV0Z40720504 Keywords : group contribution method * structure-property relations * swelling Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.203, year: 2009

Acid-base properties of the alumina surface: influence of the titration procedures on the microcalorimetric results.

Science.gov (United States)

Morel, Jean-Pierre; Marmier, Nicolas; Hurel, Charlotte; Morel-Desrosiers, Nicole

2009-10-01

The enthalpy changes associated with the protonation and deprotonation of an alumina surface have been determined on the basis of microcalorimetry experiments and acid-base potentiometric titrations at 25 degrees C. It has been shown that the results may vary significantly according to the experimental procedure. In order to do so, the potentiometric and microcalorimetric titrations have been carried out first from an acidic pH to basic pH and second from a pH near the pH(zpc) of alumina to acidic or basic pH. It has been demonstrated that the pK(a) values deduced from the potentiometric titrations are the same whatever the experimental protocol whereas the only way to obtain meaningful enthalpies of proton exchange is to carry out microcalorimetric titrations by starting around the point of zero charge.

Acidic surface functional groups and mineral elements in Lakra coal (Sindh, Pakistan)

International Nuclear Information System (INIS)

Saeed, K.; Ishaq, M.; Ahjmad, I.; Shakirullah, M.; Haider, S.

2010-01-01

Surface acidity of virgin coal (Lakra Sindh, Pakistan) and variously extracted/leached coal samples with HNO/sub 3/ NaOH, and KMnO/sub 4/, were investigated by aqueous potentiometric titration employing KOH as a titrant. The titration curve of virgin coal showed that its surface might contain carboxylic, carbonyl, phenolic and other weak acidic functional groups such as enols and C-H bond. The titration curves of leached coal samples showed inflections at pH 4-11, being not similar the inflections of carboxylic groups. This inflection might be given by functional groups like CO/sub 2/, phenolic, enols and C-H. Mineral matter such as Fe, K, Zn, Mn and Ni were determined in the ash of coal by atomic absorption spectrophotometer and was found that Fe (3104 micro g/g) in the highest and Ni (36.05 micro g/g) in the lowest quantity is present in virgin coal sample. (author)

Analysis of the sorption properties of different soils using water vapour adsorption and potentiometric titration methods

Science.gov (United States)

Skic, Kamil; Boguta, Patrycja; Sokołowska, Zofia

2016-07-01

Parameters of specific surface area as well as surface charge were used to determine and compare sorption properties of soils with different physicochemical characteristics. The gravimetric method was used to obtain water vapour isotherms and then specific surface areas, whereas surface charge was estimated from potentiometric titration curves. The specific surface area varied from 12.55 to 132.69 m2 g-1 for Haplic Cambisol and Mollic Gleysol soil, respectively, and generally decreased with pH (R=0.835; α = 0.05) and when bulk density (R=-0.736; α = 0.05) as well as ash content (R=-0.751; α = 0.05) increased. In the case of surface charge, the values ranged from 63.00 to 844.67 μmol g-1 Haplic Fluvisol and Mollic Gleysol, respecively. Organic matter gave significant contributions to the specific surface area and cation exchange capacity due to the large surface area and numerous surface functional groups, containing adsorption sites for water vapour molecules and for ions. The values of cation exchange capacity and specific surface area correlated linearly at the level of R=0.985; α = 0.05.

Titration of individual strains in trivalent live-attenuated influenza vaccine without neutralization.

Science.gov (United States)

Sirinonthanawech, Naraporn; Surichan, Somchaiya; Namsai, Aphinya; Puthavathana, Pilaipan; Auewarakul, Prasert; Kongchanagul, Alita

2016-11-01

Formulation and quality control of trivalent live-attenuated influenza vaccine requires titration of infectivity of individual strains in the trivalent mix. This is usually performed by selective neutralization of two of the three strains and titration of the un-neutralized strain in cell culture or embryonated eggs. This procedure requires standard sera with high neutralizing titer against each of the three strains. Obtaining standard sera, which can specifically neutralize only the corresponding strain of influenza viruses and is able to completely neutralize high concentration of virus in the vaccine samples, can be a problem for many vaccine manufacturers as vaccine stocks usually have very high viral titers and complete neutralization may not be obtained. Here an alternative approach for titration of individual strain in trivalent vaccine without the selective neutralization is presented. This was done by detecting individual strains with specific antibodies in an end-point titration of a trivalent vaccine in cell culture. Similar titers were observed in monovalent and trivalent vaccines for influenza A H3N2 and influenza B strains, whereas the influenza A H1N1 strain did not grow well in cell culture. Viral interference among the vaccine strains was not observed. Therefore, providing that vaccine strains grow well in cell culture, this assay can reliably determine the potency of individual strains in trivalent live-attenuated influenza vaccines. Copyright © 2016 Elsevier B.V. All rights reserved.

Equivalence-point electromigration acid-base titration via moving neutralization boundary electrophoresis.

Science.gov (United States)

Yang, Qing; Fan, Liu-Yin; Huang, Shan-Sheng; Zhang, Wei; Cao, Cheng-Xi

2011-04-01

In this paper, we developed a novel method of acid-base titration, viz. the electromigration acid-base titration (EABT), via a moving neutralization boundary (MNR). With HCl and NaOH as the model strong acid and base, respectively, we conducted the experiments on the EABT via the method of moving neutralization boundary for the first time. The experiments revealed that (i) the concentration of agarose gel, the voltage used and the content of background electrolyte (KCl) had evident influence on the boundary movement; (ii) the movement length was a function of the running time under the constant acid and base concentrations; and (iii) there was a good linearity between the length and natural logarithmic concentration of HCl under the optimized conditions, and the linearity could be used to detect the concentration of acid. The experiments further manifested that (i) the RSD values of intra-day and inter-day runs were less than 1.59 and 3.76%, respectively, indicating similar precision and stability in capillary electrophoresis or HPLC; (ii) the indicators with different pK(a) values had no obvious effect on EABT, distinguishing strong influence on the judgment of equivalence-point titration in the classic one; and (iii) the constant equivalence-point titration always existed in the EABT, rather than the classic volumetric analysis. Additionally, the EABT could be put to good use for the determination of actual acid concentrations. The experimental results achieved herein showed a new general guidance for the development of classic volumetric analysis and element (e.g. nitrogen) content analysis in protein chemistry. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A group contribution method to estimate the densities of ionic liquids

International Nuclear Information System (INIS)

Qiao Yan; Ma Youguang; Huo Yan; Ma Peisheng; Xia Shuqian

2010-01-01

Densities of ionic liquids at different temperature and pressure were collected from 84 references. The collection contains 7381 data points derived from 123 pure ionic liquids and 13 kinds of binary ionic liquids mixtures. In terms of the collected database, a group contribution method based on 51 groups was used to predict the densities of ionic liquids. In group partition, the effect of interaction among several substitutes on the same center was considered. The same structure in different substitutes may have different group values. According to the estimation of pure ionic liquids' densities, the results show that the average relative error is 0.88% and the standard deviation (S) is 0.0181. Using the set of group values three pure ionic liquids densities were predicted, the average relative error is 0.27% and the S is 0.0048. For ionic liquid mixtures, they are thought considered as idea mixtures, so the group contribution method was used to estimate their densities and the average relative error is 1.22% with S is 0.0607. And the method can also be used to estimate the densities of MCl x type ionic liquids which are produced by mixing an ionic liquid with a Cl - anion and a kind of metal chloride.

Estimation of uncertainty in pKa values determined by potentiometric titration.

Science.gov (United States)

Koort, Eve; Herodes, Koit; Pihl, Viljar; Leito, Ivo

2004-06-01

A procedure is presented for estimation of uncertainty in measurement of the pK(a) of a weak acid by potentiometric titration. The procedure is based on the ISO GUM. The core of the procedure is a mathematical model that involves 40 input parameters. A novel approach is used for taking into account the purity of the acid, the impurities are not treated as inert compounds only, their possible acidic dissociation is also taken into account. Application to an example of practical pK(a) determination is presented. Altogether 67 different sources of uncertainty are identified and quantified within the example. The relative importance of different uncertainty sources is discussed. The most important source of uncertainty (with the experimental set-up of the example) is the uncertainty of pH measurement followed by the accuracy of the burette and the uncertainty of weighing. The procedure gives uncertainty separately for each point of the titration curve. The uncertainty depends on the amount of titrant added, being lowest in the central part of the titration curve. The possibilities of reducing the uncertainty and interpreting the drift of the pK(a) values obtained from the same curve are discussed.

Clinical Effectiveness and Dose Titration in Pediatric Practice

Directory of Open Access Journals (Sweden)

Yu.V. Marushko

2016-02-01

Full Text Available The paper is devoted to the questions of usage of one of the popular antipyretic and anesthetic drug in pediatric practice — ibuprofen. In the article there are generalized literature data and own experience in ibuprofen dose titration in single dose 5 and 10 mg/kg depending on clinical situation.

Developing a multipoint titration method with a variable dose implementation for anaerobic digestion monitoring.

Science.gov (United States)

Salonen, K; Leisola, M; Eerikäinen, T

2009-01-01

Determination of metabolites from an anaerobic digester with an acid base titration is considered as superior method for many reasons. This paper describes a practical at line compatible multipoint titration method. The titration procedure was improved by speed and data quality. A simple and novel control algorithm for estimating a variable titrant dose was derived for this purpose. This non-linear PI-controller like algorithm does not require any preliminary information from sample. Performance of this controller is superior compared to traditional linear PI-controllers. In addition, simplification for presenting polyprotic acids as a sum of multiple monoprotic acids is introduced along with a mathematical error examination. A method for inclusion of the ionic strength effect with stepwise iteration is shown. The titration model is presented with matrix notations enabling simple computation of all concentration estimates. All methods and algorithms are illustrated in the experimental part. A linear correlation better than 0.999 was obtained for both acetate and phosphate used as model compounds with slopes of 0.98 and 1.00 and average standard deviations of 0.6% and 0.8%, respectively. Furthermore, insensitivity of the presented method for overlapping buffer capacity curves was shown.

A predictive group-contribution simplified PC-SAFT equation of state: Application to polymer systems

DEFF Research Database (Denmark)

Tihic, Amra; Kontogeorgis, Georgios; von Solms, Nicolas

2008-01-01

A group-contribution (GC) method is coupled with the molecular-based perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (EoS) to predict its characteristic pure compound parameters. The estimation of group contributions for the parameters is based on a parameter...... are the molecular structure of the polymer of interest in terms of functional groups and a single binary interaction parameter for accurate mixture calculations....

[Sources of error in the European Pharmacopoeia assay of halide salts of organic bases by titration with alkali].

Science.gov (United States)

Kószeginé, S H; Ráfliné, R Z; Paál, T; Török, I

2000-01-01

A short overview has been given by the authors on the titrimetric assay methods of halide salts of organic bases in the pharmacopoeias of greatest importance. The alternative procedures introduced by the European Pharmacopoeia Commission some years ago to replace the non-aqueous titration with perchloric acid in the presence of mercuric acetate have also been presented and evaluated. The authors investigated the limits of applicability and the sources of systematic errors (bias) of the strongly preferred titration with sodium hydroxide in an alcoholic medium. To assess the bias due to the differences between the results calculated from the two inflexion points of the titration curves and the two real endpoints corresponding to the strong and weak acids, respectively, the mathematical analysis of the titration curve function was carried out. This bias, generally negligible when the pH change near the endpoint of the titration is more than 1 unit, is the function of the concentration, the apparent pK of the analyte and the ionic product of water (ethanol) in the alcohol-water mixtures. Using the validation data gained for the method with the titration of ephedrine hydrochloride the authors analysed the impact of carbon dioxide in the titration medium on the additive and proportional systematic errors of the method. The newly introduced standardisation procedure of the European Pharmacopoeia for the sodium hydroxide titrant to decrease the systematic errors caused by carbon dioxide has also been evaluated.

Clinical predictors of central sleep apnea evoked by positive airway pressure titration

Directory of Open Access Journals (Sweden)

Moro M

2016-07-01

Full Text Available Marilyn Moro,1 Karen Gannon,1 Kathy Lovell,1 Margaret Merlino,1 James Mojica,2 Matt T Bianchi,1,3 1Neurology Department, 2Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, MA, USA; 3Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA Purpose: Treatment-emergent central sleep apnea (TECSA, also called complex apnea, occurs in 5%–15% of sleep apnea patients during positive airway pressure (PAP therapy, but the clinical predictors are not well understood. The goal of this study was to explore possible predictors in a clinical sleep laboratory cohort, which may highlight those at risk during clinical management.Methods: We retrospectively analyzed 728 patients who underwent PAP titration (n=422 split night; n=306 two-night. Demographics and self-reported medical comorbidities, medications, and behaviors as well as standard physiological parameters from the polysomnography (PSG data were analyzed. We used regression analysis to assess predictors of binary presence or absence of central apnea index (CAI ≥5 during split PSG (SN-PSG versus full-night PSG (FN-PSG titrations.Results: CAI ≥5 was present in 24.2% of SN-PSG and 11.4% of FN-PSG patients during titration. Male sex, maximum continuous positive airway pressure, and use of bilevel positive airway pressure were predictors of TECSA, and rapid eye movement dominance was a negative predictor, for both SN-PSG and FN-PSG patients. Self-reported narcotics were a positive predictor of TECSA, and the time spent in stage N2 sleep was a negative predictor only for SN-PSG patients. Self-reported history of stroke and the CAI during the diagnostic recording predicted TECSA only for FN-PSG patients.Conclusion: Clinical predictors of treatment-evoked central apnea spanned demographic, medical history, sleep physiology, and titration factors. Improved predictive models may be increasingly important as diagnostic and therapeutic modalities move away from the

[Photometric micro-titration model of DPPH radicals scavenging activity and its application].

Science.gov (United States)

Gao, Yun-tao; Wei, Wei; Ye, Li-qing; Li, Xiao-fen; Liu, Ping; Zhang, Hong-jiao; Yang, Lu; Yu, Jiao-jiao; Cha, Jia-wei

2015-02-01

In the present paper, the stoichiometric ratio (R) for the interreaction of DPPH radicals with the antoxidant was employed as a evaluation index for DPPH radicals scavenging activity of antioxidants. This evaluation index was related only with the stoichiometric relationship between DPPH radicals and the antioxidant, not the relationship with the initial DPPH amount and the volume of sample, which could offer a solution for the problem of poor comparability of EC50 under different conditions. A novel photometric micro-titration method was proposed for the determination of the stoichiometric ratio (R) for the interreaction of DPPH radicals with the antoxidant. The titration equation was established based on the absorbance difference (deltaA) of DPPH radicals in the titration process and the added amount of antoxidant. The stoichiometric ratio (R) for the reaction of DPPH radicals with the addition amount of antoxidant was determined by the titration equation obtained, while, the DPPH median elimination concentration (EC50) of antoxidant can be calculated by the stoichiometric ratio (R). The above photometric micro-titration model was verified using rutin as DPPH radicals scavenger. As experiment results, the stoichiometric ratio (R) of DPPH radicals to rutin was determined to be in the range of 1.817-1.846. The calculated value of EC50 was 1.196 x 10(-3), 2.392 x 10(-3), 4.819 x 10(-3) and 7.292 x 10(-3) mg x mL(-1) for 1.12 x 10(-7), 2.24 x 10(-7), 4.48 x 10(-7) and 6.72 x 10(-7) mol of the additon amount of DPPH radicals, respectively. The proposed method has better precision and reliability with smaller amount of sample than conventional method. While, the obtained stoichiometric ratio value (R) of rutin was employed to calculate the rutin median elimination concentration for DPPH EC50) according to the conditions as reported in the literatures, and the calculated results were consistent with that reported in the literatures.

Opuntia ficus indica (L.) Fruit Extract as Natural Indicator in Acid-Base Titration

OpenAIRE

Manoj A. Suva

2014-01-01

In routine experiments synthetic indicators are the choice of acid base titrations. But there are some limitations like environmental pollution, availability and higher cost which leads to search for natural compounds as an acid base indicator was started. The present work highlights theexploit of the methanolic and aqueous extract of the fruit of Opuntia ficus indica plants as a natural acid base indicator in acid base titrations. Opuntia ficus indica plant was identified and fruits were was...

A dipstick sensor for coulometric acid-base titrations

NARCIS (Netherlands)

Olthuis, Wouter; van der Schoot, B.H.; Chavez, F.; Bergveld, Piet

1989-01-01

By performing an acid-base titration by coulometric generation of OH− or H+ ions at an inert electrode in close proximity to the pH-sensitive gate of an ISFET, it is possible to determine the acid or base concentration of a solution using the ISFET as an indicator device for the equivalence point in

Impact of Uniform Methods on Interlaboratory Antibody Titration Variability: Antibody Titration and Uniform Methods.

Science.gov (United States)

Bachegowda, Lohith S; Cheng, Yan H; Long, Thomas; Shaz, Beth H

2017-01-01

-Substantial variability between different antibody titration methods prompted development and introduction of uniform methods in 2008. -To determine whether uniform methods consistently decrease interlaboratory variation in proficiency testing. -Proficiency testing data for antibody titration between 2009 and 2013 were obtained from the College of American Pathologists. Each laboratory was supplied plasma and red cells to determine anti-A and anti-D antibody titers by their standard method: gel or tube by uniform or other methods at different testing phases (immediate spin and/or room temperature [anti-A], and/or anti-human globulin [AHG: anti-A and anti-D]) with different additives. Interlaboratory variations were compared by analyzing the distribution of titer results by method and phase. -A median of 574 and 1100 responses were reported for anti-A and anti-D antibody titers, respectively, during a 5-year period. The 3 most frequent (median) methods performed for anti-A antibody were uniform tube room temperature (147.5; range, 119-159), uniform tube AHG (143.5; range, 134-150), and other tube AHG (97; range, 82-116); for anti-D antibody, the methods were other tube (451; range, 431-465), uniform tube (404; range, 382-462), and uniform gel (137; range, 121-153). Of the larger reported methods, uniform gel AHG phase for anti-A and anti-D antibodies had the most participants with the same result (mode). For anti-A antibody, 0 of 8 (uniform versus other tube room temperature) and 1 of 8 (uniform versus other tube AHG), and for anti-D antibody, 0 of 8 (uniform versus other tube) and 0 of 8 (uniform versus other gel) proficiency tests showed significant titer variability reduction. -Uniform methods harmonize laboratory techniques but rarely reduce interlaboratory titer variance in comparison with other methods.

Semi-automated potentiometric titration method for uranium characterization

Energy Technology Data Exchange (ETDEWEB)

Cristiano, B.F.G., E-mail: barbara@ird.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Delgado, J.U.; Silva, J.W.S. da; Barros, P.D. de; Araujo, R.M.S. de [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Lopes, R.T. [Programa de Engenharia Nuclear (PEN/COPPE), Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundao, PO Box 68509, Rio de Janeiro, 21945-970 RJ (Brazil)

2012-07-15

The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. - Highlights: Black-Right-Pointing-Pointer We developed a semi-automatic version of potentiometric titration method. Black-Right-Pointing-Pointer The method is used for certification and characterization of uranium compounds. Black-Right-Pointing-Pointer The traceability of the method was assured by a K{sub 2}Cr{sub 2}O{sub 7} primary standard. Black-Right-Pointing-Pointer The results of U{sub 3}O{sub 8} reference material analyzed was consistent with certified value. Black-Right-Pointing-Pointer The uncertainty obtained, near 0.01%, is useful for characterization purposes.

Spectrophotometric titration of zirconium in siliceous materials

International Nuclear Information System (INIS)

Sugawara, K.F.; Su, Y.-S.; Strzegowski, W.R.

1978-01-01

An accurate and selective complexometric titration procedure based upon a spectrophotometrically detected end-point has been developed for the determination of zirconium in glasses, glass-ceramics and refractories. A p-bromomandelic acid separation step for zirconium imparts excellent selectivity to the procedure. The method is particularly important for the 1 to 5% concentration range where a simple, accurate and selective method for the determination of zirconium has been lacking. (author)

Determination of neptunium by redox titration

International Nuclear Information System (INIS)

Godbole, A.G.; Patil, S.K.

1979-01-01

A simple and quick method for the potentiometric determination of neptunium on the 2 to 5 mg scale has been developed. It consists of oxidation to Np(VI) by AgO or fuming with HClO 4 , destruction of excess of AgO by sulphamic acid, reduction of Np(VI) to Np(IV) with a slight excess of standard Fe(II) in 2M H 2 SO 4 and potentiometric titration of the excess of Fe(II) with standard Ce(IV). The precision is +- 0.5%. (author)

Thermometric titration of a free acid and of uranyl in spent fuel element solutions

International Nuclear Information System (INIS)

Zamek, M.; Strafelda, F.

1975-01-01

A method was elaborated of determining nitric acid in the presence of uranyl nitrate in both aqueous and non-aqueous solutions using a pyridine aqueous solution as a titration agent, and of determining excess uranyl after a hydrogen peroxide addition by a further titration using the same agent. Even a hundred-fold excess of magnesium did not disturb the titration. The method is used in operating solution analyses in the extraction fuel reprocessing in the presence of a small amount of plutonium and of fission products. The reproducibility and accuracy of the method varied in the order of tens to units per cent depending on the concentration of components to be determined. The procedure is applicable for test volumes ranging between 0.1 and 10 ml in concentrations of 1 to 10 -3 M. (author)

Operant conditioning of enhanced pain sensitivity by heat-pain titration.

Science.gov (United States)

Becker, Susanne; Kleinböhl, Dieter; Klossika, Iris; Hölzl, Rupert

2008-11-15

Operant conditioning mechanisms have been demonstrated to be important in the development of chronic pain. Most experimental studies have investigated the operant modulation of verbal pain reports with extrinsic reinforcement, such as verbal reinforcement. Whether this reflects actual changes in the subjective experience of the nociceptive stimulus remained unclear. This study replicates and extends our previous demonstration that enhanced pain sensitivity to prolonged heat-pain stimulation could be learned in healthy participants through intrinsic reinforcement (contingent changes in nociceptive input) independent of verbal pain reports. In addition, we examine whether different magnitudes of reinforcement differentially enhance pain sensitivity using an operant heat-pain titration paradigm. It is based on the previously developed non-verbal behavioral discrimination task for the assessment of sensitization, which uses discriminative down- or up-regulation of stimulus temperatures in response to changes in subjective intensity. In operant heat-pain titration, this discriminative behavior and not verbal pain report was contingently reinforced or punished by acute decreases or increases in heat-pain intensity. The magnitude of reinforcement was varied between three groups: low (N1=13), medium (N2=11) and high reinforcement (N3=12). Continuous reinforcement was applied to acquire and train the operant behavior, followed by partial reinforcement to analyze the underlying learning mechanisms. Results demonstrated that sensitization to prolonged heat-pain stimulation was enhanced by operant learning within 1h. The extent of sensitization was directly dependent on the received magnitude of reinforcement. Thus, operant learning mechanisms based on intrinsic reinforcement may provide an explanation for the gradual development of sustained hypersensitivity during pain that is becoming chronic.

Evaluation of the 5 and 8 pH point titration methods for monitoring anaerobic digesters treating solid waste.

Science.gov (United States)

Vannecke, T P W; Lampens, D R A; Ekama, G A; Volcke, E I P

2015-01-01

Simple titration methods certainly deserve consideration for on-site routine monitoring of volatile fatty acid (VFA) concentration and alkalinity during anaerobic digestion (AD), because of their simplicity, speed and cost-effectiveness. In this study, the 5 and 8 pH point titration methods for measuring the VFA concentration and carbonate system alkalinity (H2CO3*-alkalinity) were assessed and compared. For this purpose, synthetic solutions with known H2CO3*-alkalinity and VFA concentration as well as samples from anaerobic digesters treating three different kind of solid wastes were analysed. The results of these two related titration methods were verified with photometric and high-pressure liquid chromatography measurements. It was shown that photometric measurements lead to overestimations of the VFA concentration in the case of coloured samples. In contrast, the 5 pH point titration method provides an accurate estimation of the VFA concentration, clearly corresponding with the true value. Concerning the H2CO3*-alkalinity, the most accurate and precise estimations, showing very similar results for repeated measurements, were obtained using the 8 pH point titration. Overall, it was concluded that the 5 pH point titration method is the preferred method for the practical monitoring of AD of solid wastes due to its robustness, cost efficiency and user-friendliness.

Potentiometric titration in a low volume of solution for rapid assay of uranium. Application to quantitative electro-reduction of uranium(VI)

International Nuclear Information System (INIS)

Sahoo, P.; Ananthanarayanan, R.; Murali, N.; Mallika, C.; Falix Lawrence; Kamachi Mudali, U.

2012-01-01

A simple, inexpensive PC based potentiometric titration technique for the assay of uranium using low volumes of sample aliquot (25-100 μL) along with all reagents (total volume of solution being less than 2.5 mL) is presented. The technique involves modification of the well known Davies and Gray Method recommended for assay of uranium(VI) in nuclear materials by introducing an innovative potentiometric titration device with a mini cell developed in-house. After appropriate chemical conditioning the titration is completed within a couple of minutes with display of online titration plot showing the progress of titration. The first derivative plot generated immediately after titration provides information of end point. The main advantage of using this technique is to carry out titration with minimum volumes of sample and reagents generating minimum volume of wastes after titration. The validity of the technique was evaluated using standard certified samples. This technique was applied for assay of uranium in a typical sample collected from fuel reprocessing laboratory. Further, the present technique was deployed in investigating the optimum conditions for efficient in situ production of U(IV). The precision in the estimation of uranium is highly satisfactory (RSD less than 1.0%). (author)

Determination of acid–base properties of HCl acid activated palygorskite by Potentiometrie titration

OpenAIRE

N. FriniSrasra; E.Srasra

2008-01-01

The surface acidity of raw and acid activated palygorskite clay were studied by acid-base potentiometric titration. The Gran plot method was applied for the hydroxide titration and the total surface site (Hs) and the average number of protons reacted per surface site (Z) of palygorskite samples at a given ionic strength were calculated. Acid treatment increases the clay acidity and modifies its surface charge. The point of zero charge value, determined by the common crossing point of Z vs pH ...

Quantitative Determination of NTA and Other Chelating Agents in Detergents by Potentiometric Titration with Copper Ion Selective Electrode.

Science.gov (United States)

Ito, Sana; Morita, Masaki

2016-01-01

Quantitative analysis of nitrilotriacetate (NTA) in detergents by titration with Cu 2+ solution using a copper ion selective electrode was achieved. This method tolerates a wide range of pH and ingredients in detergents. In addition to NTA, other chelating agents, having relatively lower stability constants toward Cu 2+ , were also qualified with sufficient accuracy by this analytical method for model detergent formulations. The titration process was automated by automatic titrating systems available commercially.

The determination of 800 to 30 μg lead(II) by potentiometric titration with molybdate

International Nuclear Information System (INIS)

Campiglio, A.

1985-01-01

The determination of 800 to 30 μg Pb(II) by potentiometric titration with molybdate by using a lead(II)-selective electrode was investigated. Under suitable conditions, 800 to 300 μg Pb(II) in aqueous solution by automatic or manual titration with 4x10 -3 M molybdate can be determined with an accuracy of +-0.57% and +-0.45% and a precision of +-0.43% and 0.30% (standard deviation = 0.25% and 0.17%, resp.). For determining amounts of Pb(II) below 300 μg, a 2x10 -3 M molybdate solution has to be used. Although 300 to 100μg Pb(II) are determinable again in water with satisfactory results, the titration in 40% ethanol is however more reliable: in this medium, amounts of 300 to 30μg Pb(II) can be determined with an accuracy of +-1% and a precision of +-2% (standard deviation from 20 titrations of 100μg Pb(II)=0.60%). The titration of 300-800μg Pb(II) in water and of 30-300μg Pb(II) in 40% ethanol is also possible in 0.1 M NaNO 3 sub- snd 0.1 M NaClO 4 sub- medium and can be used in the lead determination in organic compounds after mineralization with HNO 3 sub-HClO 4 sub-H 2 O 2 . (Author)

Determination of the total acidity in soft drinks using potentiometric sequential injection titration.

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van Staden, J Koos F; Mashamba, M Mulalo G; Stefan, R Raluca I

2002-12-06

A potentiometric SI titration system for the determination of total acidity in soft drinks is proposed. The concept is based on the aspiration of the acid soft drink sample between two base zones into a holding coil with the volume of the first base zone twice to that of the second one and channelled by flow reversal through a reaction coil to a potentiometric sensor. A solution of 0.1 mol l(-1) sodium chloride is used as ionic strength adjustment buffer in the carrier stream. The system has been applied to the analysis of some South African soft drinks having a total acidity level of about 0.2-0.3% (w/v). The method has a sample frequency of 45 samples per h with a linear range of 0.1 and 0.6% (w/v). It is easy to use, fully computerised, and gives the results that are comparable to both automated batch titration and manual titration.

Complexometric consequent titration of bismuth-titanium mixtures in the μg-region

International Nuclear Information System (INIS)

Schaefer, H.

1975-01-01

A quantitative method is described for the determination of microquantities of bismuth and titanium. Both metals are determined complexometrically with EDTA and potentiometric equivalence point indication using a Cu-ion sensitive electrode in a consequent titration. The analysis is conducted as back-titration with standard Cu-solution. The relative error of the determination is 0.8% for bismuth (50-100 μg) and for titanium (10-30 μg) at 1.0%. Under the chosen conditions, it is possible to determine as little as 15 μg bismuth and 5 μg titanium by means of this procedure. (author)

Determination of fluoride ions in water by condutometric titration with lanthanum nitrates

International Nuclear Information System (INIS)

Alves, J.C.

1986-01-01

An alternative method for determining fluoride ions in drinking water by condutometric titration using La(NO 3 ) 3 as titrant is presented. The method is based on previous separation of fluoride from sample by distillation at 135 0 C. The pH of the distillated is adjusted between 5,5 - 6,0; ethanol is adicioned in 50% titrating the resultant solution with La(NO 3 ) 3 . In these conditions, fluoride ions are determined with accuracy respectively, 5% and 4%. Natural samples of drinking water were analysed by this method and by the ion selective method, with agreement among the results. (author) [pt

Uranium coulometric titration. Application to the determination of traces

International Nuclear Information System (INIS)

Bergey, C.

After a description of the device, the means developed to improve the titration method are presented. Coulometry enables to determine U with an accuracy of 0,1% in samples of only several tenths of a milligram. This method is rapid but not intended for routine analysis [fr

Sensitive endpoint detection for coulometric titration of microgram amounts of plutonium. Part II: Use of amperometric indication for the end point detection

International Nuclear Information System (INIS)

Chitnis, R.T.; Talnikar, S.G.; Thakur, V.A.

1981-01-01

Subsequent to the work on polarized indicator electrodes in the coulometric titration of PuO 2 2+ with electrolytically generated Fe 2+ , the possibility of applying amperometry for the endpoint detection in the same titration was explored. Earlier Moiseen et al used the amperometric indication in the coulometric titration of plutonium and have reported coefficient of variation of 0.4% for the titration of 1 mg of plutonium. The lowest amount of plutonium determined was in the range of 100 micrograms. In the present method, using similar analytical technique, the titrations of 25 micrograms and lower amounts of plutonium are reported. While titrating microgram amounts using amperometric indication, the residual currents due to the supporting electrolyte affect the titrations to a considerable extent. However, it is shown that by proper choice of the potential to be applied to the indicating electrode, the interference, due to the supporting electrolyte can be minimised. Using this technique, it is possible to titrate even a fraction of a microgram of plutonium. The precision at 0.5 microgram level is found to be about 6% and that for 5 micrograms, about 1%. (author)

An Exact Method to Determine the Conductivity of Aqueous Solutions in Acid-Base Titrations

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Norma Rodríguez-Laguna

2015-01-01

Full Text Available Several works in the literature show that it is possible to establish the analytic equations to estimate the volume V of a strong base or a strong acid (Vb and Va, resp. being added to a solution of a substance or a mix of substances during an acid-base titration, as well as the equations to estimate the first derivative of the titration plot dpH/dV, and algebraic expressions to determine the buffer β capacity with dilution βdil. This treatment allows establishing the conditions of thermodynamic equilibria for all species within a system containing a mix of species from one or from various polyacid systems. The present work shows that it is possible to determine exactly the electric conductivity of aqueous solutions for these Brønsted acid-base titrations, because the functional relation between this property and the composition of the system in equilibrium is well known; this is achieved using the equivalent conductivity λi values of each of the ions present in a given system. The model employed for the present work confirms the experimental outcomes with the H2SO4, B(OH3, CH3COOH, and H3PO4 aqueous solutions’ titration.

Improved methylene blue two-phase titration method for determining cationic surfactant concentration in high-salinity brine.

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Cui, Leyu; Puerto, Maura; López-Salinas, José L; Biswal, Sibani L; Hirasaki, George J

2014-11-18

The methylene blue (MB) two-phase titration method is a rapid and efficient method for determining the concentrations of anionic surfactants. The point at which the aqueous and chloroform phases appear equally blue is called Epton's end point. However, many inorganic anions, e.g., Cl(-), NO3(-), Br(-), and I(-), can form ion pairs with MB(+) and interfere with Epton's end point, resulting in the failure of the MB two-phase titration in high-salinity brine. Here we present a method to extend the MB two-phase titration method for determining the concentration of various cationic surfactants in both deionized water and high-salinity brine (22% total dissolved solid). A colorless end point, at which the blue color is completely transferred from the aqueous phase to the chloroform phase, is proposed as titration end point. Light absorbance at the characteristic wavelength of MB is measured using a spectrophotometer. When the absorbance falls below a threshold value of 0.04, the aqueous phase is considered colorless, indicating that the end point has been reached. By using this improved method, the overall error for the titration of a permanent cationic surfactant, e.g., dodecyltrimethylammonium bromide, in deionized (DI) water and high-salinity brine is 1.274% and 1.322% with limits of detection (LOD) of 0.149 and 0.215 mM, respectively. Compared to the traditional acid-base titration method, the error of this improved method for a switchable cationic surfactant, e.g., tertiary amine surfactant (Ethomeen C12), is 2.22% in DI water and 0.106% with LOD of 0.369 and 0.439 mM, respectively.

Control of OSA during automatic positive airway pressure titration in a clinical case series: predictors and accuracy of device download data.

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Huang, Hsin-Chia Carol; Hillman, David R; McArdle, Nigel

2012-09-01

To investigate the factors associated with physiologic control of obstructive sleep apnea (OSA) during automatic positive airway pressure (APAP) titration in a clinical series. To also assess the usefulness of apnea-hypopnea index (AHI) data downloaded from the APAP device (Dev AHI). Retrospective review of a consecutive series of patients with OSA who underwent APAP titration (Autoset Spirit, ResMed, Bella Vista, New South Wales, Australia ) with simultaneous polysomnographic (PSG) monitoring in the sleep laboratory. Tertiary sleep clinic. There were 190 consecutive patients with OSA referred for APAP titration. There were 58% of patients who achieved optimal or good control of OSA (titration PSG AHI titration. The independent predictors of titration PSG AHI were a history of cardiac disease and elevated central apnea and arousal indices during the diagnostic study. Although the median and interquartile range (IQR) AHI from the device (7.0, 3.9-11.6 events/hr) was only slightly less than the PSG AHI (7.8, 3.9-14.4 events/hr, P = 0.04) during titration, case-by-case agreement between the two measures was poor (chi-square titration is often poor, and close clinical follow-up is particularly needed in patients with a history of cardiac disease or with high arousal or central apnea indices on the diagnostic study. Device AHI does not reliably assess control during APAP titration, and PSG assessment may be required if clinical response to treatment is poor. The findings relate to the ResMed AutoSet device and may not apply to other devices.

Determination of opium and strychnos alkaloids by radiometric titrations with potassium thallium(I) iodide reagent

International Nuclear Information System (INIS)

Rama Rao, V.V.; Singh, N.J.; Tandon, S.N.

1980-01-01

The titrations were carried out by the batch method in test tubes, using 204 Tl-labelled potassium thallium(I) iodide as precipitant for alkaloids such as codeine, morphine, narcotine, papaverine, thebaine, strychnine and brucine. Direct and reverse titrations were investigated including sensitivity and accuracy. Codeine and narcotine were determined in some pharmaceutical preparations such as codeine sulfate tablets, codopyrin tablets and coscopin syrup

Thermodynamics of ion binding to phosphatidic acid bilayers. Titration calorimetry of the heat of dissociation of DMPA.

Science.gov (United States)

Blume, A; Tuchtenhagen, J

1992-05-19

The heat of dissociation of the second proton of 1,2-dimyristoylphosphatidic acid (DMPA) was studied as a function of temperature using titration calorimetry. The dissociation of the second proton of DMPA was induced by addition of NaOH. From the calorimetric titration experiment, the intrinsic pK0 for the dissociation reaction could be determined by applying the Gouy-Chapman theory. pK0 decreases with temperature from ca. 6.2 at 11 degrees C to 5.4 at 54 degrees C. From the total heat of reaction, the dissociation enthalpy, delta Hdiss, was determined by subtracting the heat of neutralization of water and the heat of dilution of NaOH. In the temperature range between 2 and 23 degrees C, delta Hdiss is endothermic with an average value of ca. 2.5 kcal.mol-1 and shows no clear-cut temperature dependence. In the temperature range between 23 and 52 degrees C, delta Hdiss calculated after subtraction of the heat of neutralization and dilution is not the true dissociation enthalpy but includes contributions from the phase transition enthalpy, delta Htrans, as the pH jump induces a transition from the gel to the liquid-crystalline phase. The delta Cp for the reaction enthalpy observed in this temperature range is positive. Above 53 degrees C, the pH jump induces again only the dissociation of the second proton, and the bilayers stay in the liquid-crystalline phase. In this temperature range, delta Hdiss seems to decrease with temperature. The thermodynamic data from titration calorimetry and differential scanning calorimetry as a function of pH can be combined to construct a complete enthalpy-temperature diagram of DMPA in its two ionization states.

Titrating decision processes in the mental rotation task.

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Provost, Alexander; Heathcote, Andrew

2015-10-01

Shepard and Metzler's (1971) seminal mental-rotation task-which requires participants to decide if 1 object is a rotated version of another or its mirror image-has played a central role in the study of spatial cognition. We provide the first quantitative model of behavior in this task that is comprehensive in the sense of simultaneously providing an account of both error rates and the full distribution of response times. We used Brown and Heathcote's (2008) model of choice processing to separate out the contributions of mental rotation and decision stages. This model-based titration process was applied to data from a paradigm where converging evidence supported performance being based on rotation rather than other strategies. Stimuli were similar to Shepard and Metzler's block figures except a long major axis made rotation angle well defined for mirror stimuli, enabling comprehensive modeling of both mirror and normal responses. Results supported a mental rotation stage based on Larsen's (2014) model, where rotation takes a variable amount of time with a mean and variance that increase linearly with rotation angle. Differences in response threshold differences were largely responsible for mirror responses being slowed, and for errors increasing with rotation angle for some participants. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Competition over personal resources favors contribution to shared resources in human groups.

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Jessica L Barker

Full Text Available Members of social groups face a trade-off between investing selfish effort for themselves and investing cooperative effort to produce a shared group resource. Many group resources are shared equitably: they may be intrinsically non-excludable public goods, such as vigilance against predators, or so large that there is little cost to sharing, such as cooperatively hunted big game. However, group members' personal resources, such as food hunted individually, may be monopolizable. In such cases, an individual may benefit by investing effort in taking others' personal resources, and in defending one's own resources against others. We use a game theoretic "tug-of-war" model to predict that when such competition over personal resources is possible, players will contribute more towards a group resource, and also obtain higher payoffs from doing so. We test and find support for these predictions in two laboratory economic games with humans, comparing people's investment decisions in games with and without the options to compete over personal resources or invest in a group resource. Our results help explain why people cooperatively contribute to group resources, suggest how a tragedy of the commons may be avoided, and highlight unifying features in the evolution of cooperation and competition in human and non-human societies.

Single-experiment displacement assay for quantifying high-affinity binding by isothermal titration calorimetry.

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Krainer, Georg; Keller, Sandro

2015-04-01

Isothermal titration calorimetry (ITC) is the gold standard for dissecting the thermodynamics of a biomolecular binding process within a single experiment. However, reliable determination of the dissociation constant (KD) from a single titration is typically limited to the range 100 μM>KD>1 nM. Interactions characterized by a lower KD can be assessed indirectly by so-called competition or displacement assays, provided that a suitable competitive ligand is available whose KD falls within the directly accessible window. However, this protocol is limited by the fact that it necessitates at least two titrations to characterize one high-affinity inhibitor, resulting in considerable consumption of both sample material and time. Here, we introduce a fast and efficient ITC displacement assay that allows for the simultaneous characterization of both a high-affinity ligand and a moderate-affinity ligand competing for the same binding site on a receptor within a single experiment. The protocol is based on a titration of the high-affinity ligand into a solution containing the moderate-affinity ligand bound to the receptor present in excess. The resulting biphasic binding isotherm enables accurate and precise determination of KD values and binding enthalpies (ΔH) of both ligands. We discuss the theoretical background underlying the approach, demonstrate its practical application to metal ion chelation, explore its potential and limitations with the aid of simulations and statistical analyses, and elaborate on potential applications to protein-inhibitor interactions. Copyright © 2014 Elsevier Inc. All rights reserved.

NABTIT-a computer program for non-aqueous acid-base titration.

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Budevsky, O; Zikolova, T; Tencheva, J

1988-11-01

A program NABTIT written in BASIC has been developed for the treatment of data (ml/mV) obtained from potentiometric acid-base titrations in non-aqueous solvents. No preliminary information on equilibrium constants is required for the input. The treatment of the data is based on known equations and uses least-squares procedures. The essence of the method is to determine the equivalence volume (V(e)) accurately, and to use the data acquired by adding titrant after V(e) for the pH*-calibration of the non-aqueous potentiometric cell. As a by-product or the calculations, the pK* value of the substance titrated is also obtained, and in some cases the autoprotolysis constant of the medium (pK*(s)). Good agreement between experiment and theory was found in the treatment of data obtained for water and methanol-water mixtures.

Molecular Characterization of the Gas-Particle Interface of Soot Sampled from a Diesel Engine Using a Titration Method.

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Tapia, A; Salgado, M S; Martín, María Pilar; Lapuerta, M; Rodríguez-Fernández, J; Rossi, M J; Cabañas, B

2016-03-15

Surface functional groups of two different types of combustion aerosols, a conventional diesel (EN 590) and a hydrotreated vegetable oil (HVO) soot, have been investigated using heterogeneous chemistry (i.e., gas-particle surface reactions). A commercial sample of amorphous carbon (Printex XE2-B) was analyzed as a reference substrate. A Knudsen flow reactor was used to carry out the experiments under molecular flow conditions. The selected gases for the titration experiments were: N(CH3)3 for the identification of acidic sites, NH2OH for the presence of carbonyl groups, CF3COOH and HCl for basic sites of different strength, and O3 and NO2 for reducing groups. Reactivity with N(CH3)3 indicates a lower density of acidic functionalities for Printex XE2-B in relation to diesel and HVO soot. Results for NH2OH experiments indicates that commercial amorphous carbon exhibits a lower abundance of available carbonyl groups at the interface compared to the results from diesel and HVO soot, the latter being the one with the largest abundance of carbonyl functions. Reactions with acids indicate the presence of weak basic oxides on the particle surface that preferentially interact with the strong acid CF3COOH. Finally, reactions with O3 and NO2 reveal that diesel and especially HVO have a significantly higher reactivity with both oxidizers compared to that of Printex XE2-B because they have more reducing sites by roughly a factor of 10 and 30, respectively. The kinetics of titration reactions have also been investigated.

Determination of the titratable acidity and the pH of wine based on potentiometric flow injection analysis.

Science.gov (United States)

Vahl, Katja; Kahlert, Heike; von Mühlen, Lisandro; Albrecht, Anja; Meyer, Gabriele; Behnert, Jürgen

2013-07-15

A FIA system using a pH-sensitive detector based on a graphite/quinhydrone/silicone composite electrode was applied to determine sequentially the titratable acidity and the pH of wine, as well as the sum of calcium and magnesium ions. For all measurements the same FIA configuration was used employing different carrier solutions. The results for the determination of acidity and pH are in good agreement with those obtained by classical potentiometric titrations and by pH measurements using a conventional glass electrode. The standard deviation was less than 1.5% for both kinds of measurements and the sample volume was 150 μL. The method allows about 40 determinations of titratable acidity per hour and 30 pH measurements per hour. The titration method can be adjusted to the legal requirements in USA and Europe. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of trace amounts of thorium and lanthanides by successive titrations using semi-xylenol orange with spectrophotometric end-point indication

International Nuclear Information System (INIS)

Hafez, M.A.E.; Abdallah, A.M.A.; El-Gany, N.E.A.

1990-01-01

The precision and accuracy attainable in successive titrations of Th 4+ and either La 3+ , Nd 3+ or Gd 3+ with a 0.001 M solution of disodium ethylenediaminetetraacetate using Semi-xylenol Orange (SXO) as a metallochromic indicator were studied. Thorium (IV) was titrated at pH 2, the pH was adjusted to 5.5-5.9 by adding hexamethylenetetramine buffer and La 3+ (or Nd 3+ or Gd 3+ ) was then titrated. A comparison of the indicators SXO and Xylenol Orange for successive titrations of Th 4+ and either La 3+ , Nd 3+ or Gd 3+ was carried out. (author)

Clinical predictors of central sleep apnea evoked by positive airway pressure titration.

Science.gov (United States)

Moro, Marilyn; Gannon, Karen; Lovell, Kathy; Merlino, Margaret; Mojica, James; Bianchi, Matt T

2016-01-01

Treatment-emergent central sleep apnea (TECSA), also called complex apnea, occurs in 5%-15% of sleep apnea patients during positive airway pressure (PAP) therapy, but the clinical predictors are not well understood. The goal of this study was to explore possible predictors in a clinical sleep laboratory cohort, which may highlight those at risk during clinical management. We retrospectively analyzed 728 patients who underwent PAP titration (n=422 split-night; n=306 two-night). Demographics and self-reported medical comorbidities, medications, and behaviors as well as standard physiological parameters from the polysomnography (PSG) data were analyzed. We used regression analysis to assess predictors of binary presence or absence of central apnea index (CAI) ≥5 during split-night PSG (SN-PSG) versus full-night PSG (FN-PSG) titrations. CAI ≥5 was present in 24.2% of SN-PSG and 11.4% of FN-PSG patients during titration. Male sex, maximum continuous positive airway pressure, and use of bilevel positive airway pressure were predictors of TECSA, and rapid eye movement dominance was a negative predictor, for both SN-PSG and FN-PSG patients. Self-reported narcotics were a positive predictor of TECSA, and the time spent in stage N2 sleep was a negative predictor only for SN-PSG patients. Self-reported history of stroke and the CAI during the diagnostic recording predicted TECSA only for FN-PSG patients. Clinical predictors of treatment-evoked central apnea spanned demographic, medical history, sleep physiology, and titration factors. Improved predictive models may be increasingly important as diagnostic and therapeutic modalities move away from the laboratory setting, even as PSG remains the gold standard for characterizing primary central apnea and TECSA.

Automated sample-processing and titration system for determining uranium in nuclear materials

International Nuclear Information System (INIS)

Harrar, J.E.; Boyle, W.G.; Breshears, J.D.; Pomernacki, C.L.; Brand, H.R.; Kray, A.M.; Sherry, R.J.; Pastrone, J.A.

1977-01-01

The system is designed for accurate, precise, and selective determination of from 10 to 180 mg of uranium in 2 to 12 cm 3 of solution. Samples, standards, and their solutions are handled on a weight basis. These weights, together with their appropriate identification numbers, are stored in computer memory and are used automatically in the assay calculations after each titration. The measurement technique (controlled-current coulometry) is based on the Davies-Gray and New Brunswick Laboratory method, in which U(VI) is reduced to U(IV) in strong H 3 PO 4 , followed by titration of the U(IV) with electrogenerated V(V). Solution pretreatment and titration are automatic. The analyzer is able to process 44 samples per loading of the sample changer, at a rate of 4 to 9 samples per hour. The system includes a comprehensive fault-monitoring system that detects analytical errors, guards against abnormal conditions which might cause errors, and prevents unsafe operation. A detailed description of the system, information on the reliability of the component subsystems, and a summary of its evaluation by the New Brunswick Laboratory are presented

The efficacy of three different mask styles on a PAP titration night.

Science.gov (United States)

Ebben, Matthew R; Oyegbile, Temitayo; Pollak, Charles P

2012-06-01

This study compared the efficacy of three different masks, nasal pillows, nasal masks and full face (oronasal) masks, during a single night of titration with continuous positive airway pressure (CPAP). Fifty five subjects that included men (n=33) and women (n=22) were randomly assigned to one of three masks and underwent a routine titration with incremental CPAP applied through the different masks. CPAP applied through the nasal pillows and nasal mask was equally effective in treating mild, moderate, and severe sleep apnea. However, CPAP applied through the oronasal mask required a significantly higher pressure compared to nasal masks to treat moderately severe (2.8 cm of H(2)O ± 2.1 SD) and severe (6.0 cm of H(2)O ± 3.2 SD) obstructive sleep apnea. CPAP applied with either nasal mask was effective in treating mild, moderate, and severe sleep apnea. The oronasal mask required significantly higher pressures in subjects with moderate to severe disease. Therefore, when changing from a nasal to an oronasal mask, a repeat titration is required to ensure effective treatment of sleep apnea, especially in patients with moderate to severe disease. Copyright © 2012 Elsevier B.V. All rights reserved.

The Effect of Metal Concentration on the Parameters Derived from Complexometric Titrations of Trace Elements in Seawater—A Model Study

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Martha Gledhill

2017-08-01

Full Text Available In this study we examine the impact of dissolved metal concentrations on the parameters that are commonly determined from complexometric titrations in seawater. We use the non-ideal competitive adsorption (NICA model within the framework of the chemical speciation program visual MINTEQ with iron as a model metal. We demonstrate that dissolved iron concentrations effect the determined parameters for a heterogeneous binding site distribution with a fixed concentration of dissolved organic carbon. The commonly used terms “ligand concentration” and “binding constant” are therefore dependent on metal concentration, so we adopt the terminology suggested by Town and Filella (2000 and use the terms ligand quotient and stability quotient here. The systematic increase in the ligand quotient with dissolved iron concentration likely contributes toward the trend of increasing ligand quotient with dissolved iron concentration observed in field studies, and makes it hard to assign an objective meaning to the parameter. We suggest that calculation of the side reaction coefficient, a parameter that describes the probability that any added metal will be complexed, could be less prone to bias and misinterpretation than calculation of conditional stability and ligand quotients. We explore the impact of experimental design on side reaction coefficients by applying different detection windows, and multiwindow and reverse titration approaches. We identify the method that results in the best estimates of side reaction coefficients over a range of iron concentrations between 0.1 and 1.5 nmol L−1. We find that single window titrations can only reliably estimate side reaction coefficients over a limited range of iron concentrations. Multiwindow titrations provided estimates of side reaction coefficients within the 99% confidence interval of the values calculated directly from the NICA model at all iron concentrations examined here. We recommend that future

Implementation of a web-based tool for patient medication self-management: the Medication Self-titration Evaluation Programme (Med-STEP for blood pressure control

Directory of Open Access Journals (Sweden)

Richard W Grant

2013-12-01

Full Text Available Background Informatics tools may help support hypertension management.Objective To design, implement and evaluate a web-based system for patient anti-hypertensive medication self-titration.Methods Study stages included: six focus groups (50 patients to identify barriers/facilitators to patient medication self-titration, software design informed by qualitative analysis of focus group responses and a six-month single-arm pilot study (20 patients to assess implementation feasibility.Results Focus groups emphasised patient need to feel confident that their own primary care providers were directly involved and approved of the titration protocol. Physicians required 3.3 ± 2.8 minutes/patient to create individualised six-step medication pathways for once-monthly blood pressure evaluations. Pilot participants (mean age of 51.5 ± 11 years, 45% women, mean baseline blood pressure 139/84 ± 12.2/7.5 mmHg had five medication increases, two non-adherence self-reports, 52months not requiring medication changes, 24 skipped months and 17 months with no evaluations due to technical issues. Four pilot patients dropped out before study completion. From baseline to study completion, blood pressure decreased among the 16 patients remaining in the study (8.0/4.7 mmHg, p = 0.03 for both systolic and diastolic pressures.Conclusions Lessons learned included the benefit of qualitative patient analysis prior to system development and the feasibility of physicians designing individual treatment pathways. Any potential clinical benefits were offset by technical problems, the tendency for patients to skip their monthly self-evaluations and drop outs. To be more widely adopted such systems must effectively generalise to a wider range of patients and be integrated into clinical workflow.

Constant-pH molecular dynamics using stochastic titration

Science.gov (United States)

Baptista, António M.; Teixeira, Vitor H.; Soares, Cláudio M.

2002-09-01

A new method is proposed for performing constant-pH molecular dynamics (MD) simulations, that is, MD simulations where pH is one of the external thermodynamic parameters, like the temperature or the pressure. The protonation state of each titrable site in the solute is allowed to change during a molecular mechanics (MM) MD simulation, the new states being obtained from a combination of continuum electrostatics (CE) calculations and Monte Carlo (MC) simulation of protonation equilibrium. The coupling between the MM/MD and CE/MC algorithms is done in a way that ensures a proper Markov chain, sampling from the intended semigrand canonical distribution. This stochastic titration method is applied to succinic acid, aimed at illustrating the method and examining the choice of its adjustable parameters. The complete titration of succinic acid, using constant-pH MD simulations at different pH values, gives a clear picture of the coupling between the trans/gauche isomerization and the protonation process, making it possible to reconcile some apparently contradictory results of previous studies. The present constant-pH MD method is shown to require a moderate increase of computational cost when compared to the usual MD method.

Oxygen titration after resuscitation from out-of-hospital cardiac arrest: a multi-centre, randomised controlled pilot study (the EXACT pilot trial).

Science.gov (United States)

Bray, Janet E; Hein, Cindy; Smith, Karen; Stephenson, Michael; Grantham, Hugh; Finn, Judith; Stub, Dion; Cameron, Peter

2018-04-20

Recent studies suggest the administration of 100% oxygen to hyperoxic levels following return-of-spontaneous-circulation (ROSC) post-cardiac arrest may be harmful. However, the feasibility and safety of oxygen titration in the prehospital setting is unknown. We conducted a multi-centre, phase-2 study testing whether prehospital titration of oxygen results in an equivalent number of patients arriving at hospital with oxygen saturations SpO2 ≥ 94%. We enrolled unconscious adults with: sustained ROSC; initial shockable rhythm; an advanced airway; and an SpO2 ≥ 95%. Initially (Sept 2015-March 2016) patients were randomised 1:1 to either 2 litres/minute (L/min) oxygen (titrated) or >10 L/min oxygen (control) via a bag-valve reservoir. However, one site experienced a high number of desaturations (SpO2 titrated arm and this arm was changed (April 2016) to an initial reduction of oxygen to 4 L/min then, if tolerated, to 2 L/min, and the desaturation limit was decreased to titrated (n = 37: 2L/min = 20 and 2-4 L/min = 17) oxygen or control (n = 24). Patients allocated to titrated oxygen were more likely to desaturate compared to controls ((SpO2 titrated: 90% vs. control: 100%) and all patients had a SpO2 ≥ 90%. One patient (control) re-arrested. Survival to hospital discharge was similar. Oxygen titration post-ROSC is feasible in the prehospital environment, but incremental titration commencing at 4L/min oxygen flow may be needed to maintain an oxygen saturation >90% (NCT02499042). Copyright © 2018. Published by Elsevier B.V.

Determination of uranyl ion by potentiometric titration using an uranyl-selective electrode

International Nuclear Information System (INIS)

Nassory, N.S.

1990-01-01

A potentiometric titration of uranyl ion is described using an uranyl selective electrode based on a membrane containing a complex of UO 2 -bis[di-4-(1,1,3,3-tetramethylbutyl)phenyl phosphate] as an ion-exchanger and tritolyl phosphate as a solvent mediator. The titrations were carried out with various titrants: Sodium hydroxide, potassium fluoride and sodium salts of acetate, oxalate and citrate. The equivalence points were determined by Gran's method. Good results were obtained by using sodium oxalate as a titrant for the determination of uranium in several samples of ammonium diuranate. The results were quite comparable with those obtained by X-ray fluorescence spectrometry. (orig.)

Influence of kinetics on the determination of the surface reactivity of oxide suspensions by acid-base titration.

Science.gov (United States)

Duc, M; Adekola, F; Lefèvre, G; Fédoroff, M

2006-11-01

The effect of acid-base titration protocol and speed on pH measurement and surface charge calculation was studied on suspensions of gamma-alumina, hematite, goethite, and silica, whose size and porosity have been well characterized. The titration protocol has an important effect on surface charge calculation as well as on acid-base constants obtained by fitting of the titration curves. Variations of pH versus time after addition of acid or base to the suspension were interpreted as diffusion processes. Resulting apparent diffusion coefficients depend on the nature of the oxide and on its porosity.

Prediction of heat capacities and heats of vaporization of organic liquids by group contribution methods

DEFF Research Database (Denmark)

Ceriani, Roberta; Gani, Rafiqul; Meirelles, A.J.A.

2009-01-01

In the present work a group contribution method is proposed for the estimation of the heat capacity of organic liquids as a function of temperature for fatty compounds found in edible oil and biofuels industries. The data bank used for regression of the group contribution parameters (1395 values...

Potentiometric titrations of para and nitro substituted aromatic acids and their mixtures in methylethyl ketone

International Nuclear Information System (INIS)

Ozeroglu, C.; Karahan, M.

2011-01-01

In this study, it was the purpose to examine the potentiometric titrations of para and nitro substituted aromatic acids in methylethyl ketone (MEK) as a non-aqueous solvent. Good analytical results were obtained in determining the amount of each acid and the amounts of acids in their ternary mixtures by using 0.0964 N tetrabuthylammoniumhydroxyde (TBAH) as a standard titrant. Methylethyl ketone (MEK) which is a good solvent for many organic compounds and has a convenient liquid range of -86 to 80 deg. C was used for titration of the para and nitro substituted aromatic acids. A linear relationship has been found between pKa values of the para and nitro substituted aromatic acids in water and the half neutralization potential (HNP) values determined by potentiometric titration curves of the same acids in MEK. (author)

[Predictive methods versus clinical titration for the initiation of lithium therapy. A systematic review].

Science.gov (United States)

Geeraerts, I; Sienaert, P

2013-01-01

When lithium is administered, the clinician needs to know when the lithium in the patient’s blood has reached a therapeutic level. At the initiation of treatment the level is usually achieved gradually through the application of the titration method. In order to increase the efficacy of this procedure several methods for dosing lithium and for predicting lithium levels have been developed. To conduct a systematic review of the publications relating to the various methods for dosing lithium or predicting lithium levels at the initiation of therapy. We searched Medline systematically for articles published in English, French or Dutch between 1966 and April 2012 which described or studied a method for dosing lithium or for predicting the lithium level reached following a specific dosage. We screened the reference lists of relevant articles in order to locate additional papers. We found 38 lithium prediction methods, in addition to the clinical titration method. These methods can be divided into two categories: the ‘a priori’ methods and the ‘test-dose’ methods, the latter requiring the administration of a test dose of lithium. The lithium prediction methods generally achieve a therapeutic blood level faster than the clinical titration method, but none of the methods achieves convincing results. On the basis of our review, we propose that the titration method should be used as the standard method in clinical practice.

Developing and Demonstrating an Augmented Reality Colorimetric Titration Tool

Science.gov (United States)

Tee, Nicholas Yee Kwang; Gan, Hong Seng; Li, Jonathan; Cheong, Brandon Huey-Ping; Tan, Han Yen; Liew, Oi Wah; Ng, Tuck Wah

2018-01-01

The handling of chemicals in the laboratory presents a challenge in instructing large class sizes and when students are relatively new to the laboratory environment. In this work, we describe and demonstrate an augmented reality colorimetric titration tool that operates out of the smartphone or tablet of students. It allows multiple students to…

Study of complex amalgams containing alkali metals by method of broken thermometric titration

International Nuclear Information System (INIS)

Filippova, L.M.; Zebreva, A.I.; Espenbetov, A.A.

1977-01-01

Complex potassium-cadmium and sodium-cadmium amalgams containing different amounts of the alkali metal nad cadmium have been studied by thermometric titration with mercury. The experiments have been carried out in argon atmosphere at 25 deg C. As evidenced by the titration of sodium-cadmium amalgams, in the range of concentrations studied (Csub(Na)=0.71-2.95, Csub(Cd)=4.38-6.45 g-at/lHg) no solid phase is formed in them. Potassium-cadmium amalgams where the metals content is no higher than their individual solubility in mercury, display, when being mercury-titrated, negative heat effects due to solid phase formation. An estimation is made of the solid phase composition, its solubility in mercury and the heat of dissolution. The solid phase appearing in complex K-Cd amalgams is likely to contain K and Cd in a ratio 1:1 its conventional solubility product is 5.4 g-at/l Hg, and the heat of dissolution in mercury at 25 deg is -21 +-4 kJ/g-at

Determination of boron as boric acid by automatic potentiometric titration using Gran plots [in pressurized water reactor coolant

International Nuclear Information System (INIS)

Midgley, D.; Gatford, C.

1989-11-01

Boron in PWR primary coolant and related waters may be determined as boric acid by titration with sodium hydroxide, using a glass electrode as a pH indicator. Earlier work has shown that this analysis can conveniently be carried out automatically with adequate precision and accuracy for routine use, although bias became apparent at the lowest concentrations tested. The latest titrators enable the titration data to be transformed mathematically to give two linear segments, before and after the end-point (Gran plots). The results are as precise as those from other titration methods (in which the end-point is found from the point of inflexion of a plot of pH against volume of titrant), but the bias at low concentrations is much reduced. This is achieved without extra time or involvement of the operator. (author)

Barriers to and enablers of insulin self-titration in adults with Type 2 diabetes: a qualitative study.

Science.gov (United States)

McBain, H; Begum, S; Rahman, S; Mulligan, K

2017-02-01

To identify the barriers to and enablers of effective insulin self-titration in people with Type 2 diabetes. A qualitative semi-structured interview approach was used. Questions were structured according to the Theoretical Domains Framework, which outlines 14 domains that can act as barriers to and enablers of changing behaviour. Interviews were audio-recorded and transcribed verbatim. The data were coded according to the 14 domains, belief statements were created within each domain, and a frequency count of the most reported barriers and enablers was then carried out. Analyses were conducted by two researchers, and discrepancies agreed with a third researcher. A total of 18 adults with Type 2 diabetes took part in an interview. The majority were of South-Asian ethnicity (n = 8) and were men (n = 12). Their mean age was 61 years old. The mean duration of diabetes was 16 years and time on insulin 9 years. Inter-rater reliability for each of the domains varied (29-100%). The most frequently reported domains were Social Influence and Beliefs about Consequences; the least frequently reported were Optimism and Reinforcement. Interviewees reported receiving support to self-titrate from a range of sources. Self-titrating was perceived to have a range of both positive and negative consequences, as was not titrating. The findings highlight that those interviewed experienced a range of barriers and enablers when attempting to self-titrate. Improved education and training when initiating insulin treatment among adults with Type 2 diabetes, and throughout their journey on insulin therapy could help identify and address these barriers in order to optimize self-titration. © 2016 Diabetes UK.

Automation of potentiometric titration with a personal computer using ...

African Journals Online (AJOL)

sampling was designed and tested for automation of potentiometric titrations with personal ... automation permits us to carry out new types of experiments, such as those requiring ... have proved to be very useful in routine tasks but not in research, due to their ... This is done by a simple delay sub-routine in data acquisition.

SYNTHESIS OF AZO COMPOUNDS DERIVATIVE FROM EUGENOL AND ITS APPLICATION AS A TITRATION INDICATOR

Directory of Open Access Journals (Sweden)

Bambang Purwono

2010-06-01

Full Text Available The synthesis of azo compounds from eugenol has been carried out by diazotation reaction. The diazonium salt was produced by reaction of aniline and sodium nitrite in acid condition at 0-5 °C temperature to yield benzenediazonium chloride salt. The salt was then reacted with eugenol to produce the azo derivatives. The azo product was analyzed by IR, 1H-NMR, dan GC-MS spectrometer. The results showed that the reaction of benzenediazonium chloride with eugenol gave 4-allyl-2-methoxy-6-hydroxyazobenzene in 34.27% yield for 30 minutes reaction. The derivative of azo compound was dissolved in ethanol and then the color changing was observed in range of pH 9.8-11.1 from yellow to red. Application for titration indicator for acetic acid titrated with sodium hydroxide showed error less than 3.20% compared with phenol phtaline indicator.   Keywords: Eugenol, Azo compound, titration indicator

Quantitative RT-PCR for titration of replication-defective recombinant Semliki Forest virus.

Science.gov (United States)

Puglia, Ana L P; Rezende, Alexandre G; Jorge, Soraia A C; Wagner, Renaud; Pereira, Carlos A; Astray, Renato M

2013-11-01

Virus titration may constitute a drawback in the development and use of replication-defective viral vectors like Semliki Forest virus (SFV). The standardization and validation of a reverse transcription quantitative PCR (qRT-PCR) method for SFV titration is presented here. The qRT-PCR target is located within the nsp1 gene of the non-structural polyprotein SFV region (SFV RNA), which allows the strategy to be used for several different recombinant SFV constructs. Titer determinations were carried out by performing virus titration and infection assays with SFVs containing an RNA coding region for the rabies virus glycoprotein (RVGP) or green fluorescent protein (GFP). Results showed that the standardized qRT-PCR is applicable for different SFV constructs, and showed good reproducibility. To evaluate the correlation between the amount of functional SFV RNA in a virus lot and its infectivity in BHK-21 cell cultures, a temperature mediated titer decrease was performed and successfully quantitated by qRT-PCR. When used for cell infection at the same multiplicity of infection (MOI), the temperature treated SFV-RVGP samples induced the same levels of RVGP expression. Similarly, when different SFV-GFP lots with different virus titers, as accessed by qRT-PCR, were used for cell infection at the same MOI, the cultures showed comparable amounts of fluorescent cells. The data demonstrate a good correlation between the amount of virus used for infection, as measured by its SFV RNA, and the protein synthesis in the cells. In conclusion, the qRT-PCR method developed here is accurate and enables the titration of replication-defective SFV vectors, an essential aid for viral vector development as well as for establishment of production bioprocesses. Copyright © 2013 Elsevier B.V. All rights reserved.

Estimating the contribution of genetic variants to difference in incidence of disease between population groups

Science.gov (United States)

Moonesinghe, Ramal; Ioannidis, John PA; Flanders, W Dana; Yang, Quanhe; Truman, Benedict I; Khoury, Muin J

2012-01-01

Genome-wide association studies have identified multiple genetic susceptibility variants to several complex human diseases. However, risk-genotype frequency at loci showing robust associations might differ substantially among different populations. In this paper, we present methods to assess the contribution of genetic variants to the difference in the incidence of disease between different population groups for different scenarios. We derive expressions for the contribution of a single genetic variant, multiple genetic variants, and the contribution of the joint effect of a genetic variant and an environmental factor to the difference in the incidence of disease. The contribution of genetic variants to the difference in incidence increases with increasing difference in risk-genotype frequency, but declines with increasing difference in incidence between the two populations. The contribution of genetic variants also increases with increasing relative risk and the contribution of joint effect of genetic and environmental factors increases with increasing relative risk of the gene–environmental interaction. The contribution of genetic variants to the difference in incidence between two populations can be expressed as a function of the population attributable risks of the genetic variants in the two populations. The contribution of a group of genetic variants to the disparity in incidence of disease could change considerably by adding one more genetic variant to the group. Any estimate of genetic contribution to the disparity in incidence of disease between two populations at this stage seems to be an elusive goal. PMID:22333905

Estimating the contribution of genetic variants to difference in incidence of disease between population groups.

Science.gov (United States)

Moonesinghe, Ramal; Ioannidis, John P A; Flanders, W Dana; Yang, Quanhe; Truman, Benedict I; Khoury, Muin J

2012-08-01

Genome-wide association studies have identified multiple genetic susceptibility variants to several complex human diseases. However, risk-genotype frequency at loci showing robust associations might differ substantially among different populations. In this paper, we present methods to assess the contribution of genetic variants to the difference in the incidence of disease between different population groups for different scenarios. We derive expressions for the contribution of a single genetic variant, multiple genetic variants, and the contribution of the joint effect of a genetic variant and an environmental factor to the difference in the incidence of disease. The contribution of genetic variants to the difference in incidence increases with increasing difference in risk-genotype frequency, but declines with increasing difference in incidence between the two populations. The contribution of genetic variants also increases with increasing relative risk and the contribution of joint effect of genetic and environmental factors increases with increasing relative risk of the gene-environmental interaction. The contribution of genetic variants to the difference in incidence between two populations can be expressed as a function of the population attributable risks of the genetic variants in the two populations. The contribution of a group of genetic variants to the disparity in incidence of disease could change considerably by adding one more genetic variant to the group. Any estimate of genetic contribution to the disparity in incidence of disease between two populations at this stage seems to be an elusive goal.

Towards the Development of a Second-Order Approximation in Activity Coefficient Models Based on Group Contributions

DEFF Research Database (Denmark)

Abildskov, Jens; Constantinou, Leonidas; Gani, Rafiqul

1996-01-01

A simple modification of group contribution based models for estimation of liquid phase activity coefficients is proposed. The main feature of this modification is that contributions estimated from the present first-order groups in many instances are found insufficient since the first-order groups...... correlation/prediction capabilities, distinction between isomers and ability to overcome proximity effects....

Desenvolvimento de um titulador baseado na contagem de gotas Development of a titrator based on drop counting

Directory of Open Access Journals (Sweden)

André Fernando Oliveira

2010-01-01

Full Text Available TitDrop II, a practice low-cost titrator based on drop counting is proposed. A microcomputer counts drops in an opto-switch and it receives pH values from a commercial pHmeter with RS-232 serial port. The volume of drops must kept constant and the amount of base in each drop is obtained by standardization in the titrator. A linear behavior between height of reservoir of titrant and drop frequency was observed, but there is no influence of low height on drop volume. Acetic acidity in samples of vinager was compared with volumetric titration, and deviation between -2.6 to 3.9% was observed.

An on-line potentiometric sequential injection titration process analyser for the determination of acetic acid.

Science.gov (United States)

van Staden, J F; Mashamba, Mulalo G; Stefan, Raluca I

2002-09-01

An on-line potentiometric sequential injection titration process analyser for the determination of acetic acid is proposed. A solution of 0.1 mol L(-1) sodium chloride is used as carrier. Titration is achieved by aspirating acetic acid samples between two strong base-zone volumes into a holding coil and by channelling the stack of well-defined zones with flow reversal through a reaction coil to a potentiometric sensor where the peak widths were measured. A linear relationship between peak width and logarithm of the acid concentration was obtained in the range 1-9 g/100 mL. Vinegar samples were analysed without any sample pre-treatment. The method has a relative standard deviation of 0.4% with a sample frequency of 28 samples per hour. The results revealed good agreement between the proposed sequential injection and an automated batch titration method.

Her earnings: Exploring variation in wives' earning contributions across six major Asian groups and Whites.

Science.gov (United States)

Kulkarni, Veena S

2015-07-01

Previous research on understanding race-ethnic differentials in employment and economic contributions by married women has primarily focused on Blacks, Hispanics, or Whites. This study investigates variations in wives' earning contributions as measured by wives earnings as a proportion of total annual household earnings among six Asian groups, Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese relative to native born non-Hispanic White. I disaggregate the six Asian groups by their ethnicity and nativity status. Using pooled data from 2009-2011 American Community Survey, the findings show significance of human capital, hours of paid labor market engagement and nativity status. There is strong and negative association between husbands' human capital and labor supply with wives' earning contributions suggesting near universality of male-breadwinner status. Notwithstanding the commonalities, there is significant intergroup diversity. While foreign born and native born Filipina wives despite their spouses' reasonably high human capital and work hours, contribute one of the highest shares, the same cannot be said for the Asian Indians and Japanese. For foreign born Asian Indian and to some extent Japanese women, their high human capital is not translated to high earning contribution after controlling for husband's human capital. Further, nativity status impacts groups differentially. Native born Vietnamese wives contribute the greatest. Overall, the findings underscore the relevance of employing multiple conceptual frameworks in understanding earning contributions of foreign and native born Asian wives belonging to the six Asian groups, Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese. Copyright © 2015 Elsevier Inc. All rights reserved.

Going Beyond, Going Further: The Preparation of Acid-Base Titration Curves.

Science.gov (United States)

McClendon, Michael

1984-01-01

Background information, list of materials needed, and procedures used are provided for a simple technique for generating mechanically plotted acid-base titration curves. The method is suitable for second-year high school chemistry students. (JN)

Titration of Alanine Monitored by NMR Spectroscopy: A Biochemistry Laboratory Experiment

Science.gov (United States)

Waller, Francis J.; And Others

1977-01-01

The experiment described here involves simultaneous monitoring of pH and NMR chemical shifts during an aqueous titration of alpha- and beta-alanine. This experiment is designed for use in an undergraduate biochemistry course. (MR)

Direct measurement of the interaction energy between solids and gases--3. Comparison of the calorimetric titration method with the amine titration method for the determination of acid strength distribution of the silica-alumina surface

Energy Technology Data Exchange (ETDEWEB)

Taniguchi, H.; Masuda, T.; Tsutsumi, K.; Takahashi, H.

1978-07-01

Comparison of the calorimetric titration method with the amine titration method for the determination of acid strength distribution of the silica-alumina surface was carried out for a catalyst containing 13% by wt alumina and evacuated at 400/sup 0/C at 0.00001 mm Hg for five hours. The heats of adsorption of ammonia on silica-alumina poisoned with Hammett indicators of 8.2 to 3.3 pK/sub a/ were also measured to obtain the relation between the dissociation constant of the acid (pK/sub a/) and the heat of adsorption. At pK/sub a/ values of -5.6 and +3.3, the differential heats of adsorption were 76.1 and 55.1 kj/mole, respectively. The number of acid sites calculated from the heat vs. adsorbed-amount curve was about twice as large as that determined by amine titration. The discrepancy is discussed.

Natural monocrystalline pyrite as a sensor in non-aqueous solution Part I: Potentiometric titration of weak acids in, N,N-dimethylformamide, methylpyrrolidone and pyridine.

Science.gov (United States)

Mihajlović, Lj V; Mihajlović, R P; Antonijević, M M; Vukanović, B V

2004-11-15

The possibility of applying natural monocrystaline pyrite as a sensor for the potentiometric titration of weak acids in N,N-dimethylformamide, methylpyrrolidone and pyridine was investigated. The potential of this electrode in N,N-dimethylformamide, methylpyrrolidone and pyridine exhibits a sub-Nernst dependence. In N,N-dimethylformamide the slope (mV/pH) is 39.0 and in methylpyrrolidone it is 45.0. The potential jumps at the titration end-point obtained in the titration of weak acids are higher than those obtained by the application of a glass electrode as the indicator electrode The potential in the course of the titration and at the titration end-point (TEP) are rapidly established. Sodium methylate, potassium hydroxide and tetrabutylammonium hydroxide (TBAH) proved to be very suitable titrating agents for these titrations. The results obtained in the determination of the investigated weak acids deviate by 0.1-0.35% with respect to those obtained by using a glass electrode as the indicator electrode.

A rapid method for infectivity titration of Andes hantavirus using flow cytometry.

Science.gov (United States)

Barriga, Gonzalo P; Martínez-Valdebenito, Constanza; Galeno, Héctor; Ferrés, Marcela; Lozach, Pierre-Yves; Tischler, Nicole D

2013-11-01

The focus assay is currently the most commonly used technique for hantavirus titer determination. This method requires an incubation time of between 5 and 11 days to allow the appearance of foci after several rounds of viral infection. The following work presents a rapid Andes virus (ANDV) titration assay, based on viral nucleocapsid protein (N) detection in infected cells by flow cytometry. To this end, an anti-N monoclonal antibody was used that was developed and characterized previously. ANDV N could be detected as early as 6 h post-infection, while viral release was not observed until 24-48 h post-infection. Given that ANDV detection was performed during its first round of infection, a time reduction for titer determination was possible and provided results in only two days. The viral titer was calculated from the percentage of N positive cells and agreed with focus assay titers. Furthermore, the assay was applied to quantify the inhibition of ANDV cell entry by patient sera and by preventing endosome acidification. This novel hantavirus titration assay is a highly quantitative and sensitive tool that facilitates infectivity titration of virus stocks, rapid screening for antiviral drugs, and may be further used to detect and quantify infectious virus in human samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Development and validation of a simplified titration method for monitoring volatile fatty acids in anaerobic digestion.

Science.gov (United States)

Sun, Hao; Guo, Jianbin; Wu, Shubiao; Liu, Fang; Dong, Renjie

2017-09-01

The volatile fatty acids (VFAs) concentration has been considered as one of the most sensitive process performance indicators in anaerobic digestion (AD) process. However, the accurate determination of VFAs concentration in AD processes normally requires advanced equipment and complex pretreatment procedures. A simplified method with fewer sample pretreatment procedures and improved accuracy is greatly needed, particularly for on-site application. This report outlines improvements to the Nordmann method, one of the most popular titrations used for VFA monitoring. The influence of ion and solid interfering subsystems in titrated samples on results accuracy was discussed. The total solid content in titrated samples was the main factor affecting accuracy in VFA monitoring. Moreover, a high linear correlation was established between the total solids contents and VFA measurement differences between the traditional Nordmann equation and gas chromatography (GC). Accordingly, a simplified titration method was developed and validated using a semi-continuous experiment of chicken manure anaerobic digestion with various organic loading rates. The good fitting of the results obtained by this method in comparison with GC results strongly supported the potential application of this method to VFA monitoring. Copyright © 2017. Published by Elsevier Ltd.

Titration effectiveness of two autoadjustable continuous positive airway pressure devices driven by different algorithms in patients with obstructive sleep apnoea.

Science.gov (United States)

Damiani, Mario Francesco; Quaranta, Vitaliano Nicola; Tedeschi, Ersilia; Drigo, Riccardo; Ranieri, Teresa; Carratù, Pierluigi; Resta, Onofrio

2013-08-01

Nocturnal application of continuous positive airway pressure (CPAP) is the standard treatment for patients with obstructive sleep apnoea (OSA). Determination of the therapeutic pressure (CPAP titration) is usually performed by a technician in the sleep laboratory during attended polysomnography. One possible alternative to manual titration is automated titration. Indeed, during the last 15 years, devices have been developed that deliver autoadjustable CPAP (A-CPAP). The aim of the present study was to compare the titration effectiveness of two A-CPAP devices using different flow-based algorithms in patients with OSA. This is a randomized study; 79 subjects underwent two consecutive unattended home A-CPAP titration nights with two different devices (Autoset Resmed; Remstar Auto Respironics); during the third and the fourth night, patients underwent portable monitoring in the sleep laboratory during fixed CPAP at the A-CPAP recommended pressure. Bland Altman plots showed good agreement between the recommended median and maximal pressure levels obtained with the two devices. A significant improvement was observed in all the sleep parameters by both A-CPAP machines to a similar degree. It was observed that the two A-CPAP devices using different algorithms are equally effective in initial titration of CPAP. © 2013 The Authors. Respirology © 2013 Asian Pacific Society of Respirology.

On the virtue of acid–base titrations for the determination of basic sites in nitrogen doped carbon nanotubes

NARCIS (Netherlands)

Bitter, J.H.; van Dommele, S.; de Jong, K.P.

2013-01-01

The basicity and nature of basic species in nitrogen containing carbon nanotubes (NCNT) prepared under different conditions were investigated by acid–base titrations. Proton uptake curves were derived from the titration data and were used to establish the basicity (pKa) ranges of nitrogen species

Fast Proton Titration Scheme for Multiscale Modeling of Protein Solutions.

Science.gov (United States)

Teixeira, Andre Azevedo Reis; Lund, Mikael; da Silva, Fernando Luís Barroso

2010-10-12

Proton exchange between titratable amino acid residues and the surrounding solution gives rise to exciting electric processes in proteins. We present a proton titration scheme for studying acid-base equilibria in Metropolis Monte Carlo simulations where salt is treated at the Debye-Hückel level. The method, rooted in the Kirkwood model of impenetrable spheres, is applied on the three milk proteins α-lactalbumin, β-lactoglobulin, and lactoferrin, for which we investigate the net-charge, molecular dipole moment, and charge capacitance. Over a wide range of pH and salt conditions, excellent agreement is found with more elaborate simulations where salt is explicitly included. The implicit salt scheme is orders of magnitude faster than the explicit analog and allows for transparent interpretation of physical mechanisms. It is shown how the method can be expanded to multiscale modeling of aqueous salt solutions of many biomolecules with nonstatic charge distributions. Important examples are protein-protein aggregation, protein-polyelectrolyte complexation, and protein-membrane association.

Theoretical problems associated with the use of acetic anhydride as a co-solvent for the non-aqueous titration of hydrohalides of organic bases and quaternary ammonium salts.

Science.gov (United States)

Völgyi, Gergely; Béni, Szabolcs; Takács-Novák, Krisztina; Görög, Sándor

2010-01-05

A potentiometric titration study of organic base hydrohalides and quaternary ammonium salts using perchloric acid as the titrant and a mixture of acetic anhydride and acetic acid as the solvent was carried out and the titration mixture was analysed by NMR in order to clarify the chemistry of the reactions involved. It was found that in contrast to the general belief the formation of acetyl halides and titratable free acetate ion does not take place prior to the titration but NMR spectra proved the formation of acetyl halides in the course of the titration. This observation and the fact that the shape of the titration curves depends on the nature of the hydrohaloic acid bound to the base or of the anion in the quaternary ammonium salts led to the conclusion that the titrating agent is acetyl perchlorate formed in situ during the titration. Equations of the reactions involved in the titration process are shown in the paper.

Conductimetric and Potentiometric Titration of Some Hydroxylated Cinnamic Acids with Tetrabutylammonium Hydroxide in Non-Aqueous Media

OpenAIRE

AKTAŞ, A. Hakan; YAŞAR, Gülsüm; ALSANCAK, Güleren ÖZKAN

2001-01-01

In this study, four hydroxycinnamic acids, namely 3,4-dihydroxycinnamic acid, 4-hydroxycinnamic acid, 4-hydroxy --3- methoxycinnamic acid and 4-hydroxy-3,5-dimethoxycinnamic acid, were titrated conductimetrically and potentiometrically using triethylamine and tetrabutylammonium hydroxide in acetonitrile, 2-propanol, and pyridine solvents under a nitrogen atmosphere at 25 oC. In conductimetric titration with tetrabutylammonium hydroxide all of the compounds exhibited conventional s...

A quantitative mechanistic description of Ni, Zn and Ca sorption on Na-Montmorillonite. Part I: Physico-chemical characterisation and titration measurements

International Nuclear Information System (INIS)

Baeyens, B.; Bradbury, M.H.

1995-07-01

The work presented in this report is primarily concerned with characterisation studies and titration measurements on conditioned Na-montmorillonite. The starting material, SWy-1 Na-montmorillonite (Crook County, Wyoming, USA), contains background metal impurities, soluble salts and sparingly soluble minerals which can influence titration and sorption measurements and thereby lead to difficulties in the interpretation of the data. A conditioning procedure is described which yielded a purified clay material in the homoionic sodium form with a particle size 4 . The reasons for choosing a batch method, coupled with back titration of the supernatant solutions, instead of a continuous procedure, are fully discussed. Chemical analyses data for the supernatant solutions are presented in detail. The influence of background impurities, not removed by the conditioning, and cation exchange processes on the form of the titration curves were investigates. Net Na-montmorillonite titration curves at two different ionic strengths were derived which are considered to reflect only the acid/base behaviour of ≡SOH type surface sites. The acid end point in the titration data was used to estimate an ≡SOH site capacity of 0.08 moles per kg conditioned Na-montmorillonite. (author) 8 figs., 19 tabs., refs

Selective two-step titration of thorium by sulfate displacement of the diethylenetriaminepentaacetic acid complex

International Nuclear Information System (INIS)

Kiefer, P.

1980-07-01

Thorium and other metals are complexed with excess diethylenetriaminepentaacetic acid (DTPA) at pH 1.4, the excess DTPA is titrated with Bi(III) to a xylenol orange end point, sulfate is added to complex Th(IV), and the displaced DTPA again is titrated with Bi(III). Of 61 metal ions and nonmetal anions tested, only Ga(III), Sc(III), tungstate, citrate, oxalate, and thiosulfate interfere seriously. Lesser interferences are In(III), Zr(IV), V(IV), and permanganate. The standard deviation is 2 μg for 56 to 840 μg Th

Radiometric titration of thallium(III) with EDTA

International Nuclear Information System (INIS)

Rao, V.R.S.; Pulla Rao, Ch.; Tataiah, G.

1978-01-01

Radioactive solutions containing very small amounts of thallium(III) can be determined by radiometric titration using ammonia as hydrolysing agent. Aqueous solution of thallium(I) (both inactive and radioactive) is treated with bromine water till the appearance of the brown colour of bromine, and the solution is warmed to 80 deg C to expel the excess bromine. By this procedure all thallium(I) is quantitatively oxidised to thallium(III). An aqueous solution of ammonia is added to precipitate thallium(III) as thallic oxide. It is then filtered, washed with water to free it from bromide and then dissolved in 2N HCl and the solution is then standardised. 2 ml of this solution is transferred to a 20 ml volumetric flask, 1 ml of radioactive thallium(III) solution to be standardised is added as well as incremental amounts of EDTA solution and mixed thoroughly. Uncomplexed thallium(III) is then precipitated by the addition of an ammonia solution and diluted to 20 ml. Required amount of this mixture is centrifuged. The beta activity of the supernatant aliquot is measured using a GM counter. Quantitative determination of Tl(III) in the range of 1-10 μM can be carried out. The interference of cations such as Au(III), iron(III), Ga(III) can be eliminated by pretreatment of the Tl(III) solution before carrying out radiometric titration. The results obtained are reproducible and accurate to +-3%. (T.I.)

Effect of self-monitoring and medication self-titration on systolic blood pressure in hypertensive patients at high risk of cardiovascular disease: the TASMIN-SR randomized clinical trial.

Science.gov (United States)

McManus, Richard J; Mant, Jonathan; Haque, M Sayeed; Bray, Emma P; Bryan, Stirling; Greenfield, Sheila M; Jones, Miren I; Jowett, Sue; Little, Paul; Penaloza, Cristina; Schwartz, Claire; Shackleford, Helen; Shovelton, Claire; Varghese, Jinu; Williams, Bryan; Hobbs, F D Richard; Gooding, Trevor; Morrey, Ian; Fisher, Crispin; Buckley, David

2014-08-27

Self-monitoring of blood pressure with self-titration of antihypertensives (self-management) results in lower blood pressure in patients with hypertension, but there are no data about patients in high-risk groups. To determine the effect of self-monitoring with self-titration of antihypertensive medication compared with usual care on systolic blood pressure among patients with cardiovascular disease, diabetes, or chronic kidney disease. A primary care, unblinded, randomized clinical trial involving 552 patients who were aged at least 35 years with a history of stroke, coronary heart disease, diabetes, or chronic kidney disease and with baseline blood pressure of at least 130/80 mm Hg being treated at 59 UK primary care practices was conducted between March 2011 and January 2013. Self-monitoring of blood pressure combined with an individualized self-titration algorithm. During the study period, the office visit blood pressure measurement target was 130/80 mm Hg and the home measurement target was 120/75 mm Hg. Control patients received usual care consisting of seeing their health care clinician for routine blood pressure measurement and adjustment of medication if necessary. The primary outcome was the difference in systolic blood pressure between intervention and control groups at the 12-month office visit. Primary outcome data were available from 450 patients (81%). The mean baseline blood pressure was 143.1/80.5 mm Hg in the intervention group and 143.6/79.5 mm Hg in the control group. After 12 months, the mean blood pressure had decreased to 128.2/73.8 mm Hg in the intervention group and to 137.8/76.3 mm Hg in the control group, a difference of 9.2 mm Hg (95% CI, 5.7-12.7) in systolic and 3.4 mm Hg (95% CI, 1.8-5.0) in diastolic blood pressure following correction for baseline blood pressure. Multiple imputation for missing values gave similar results: the mean baseline was 143.5/80.2 mm Hg in the intervention group vs 144.2/79.9 mm Hg in the control group, and

Acid-base titrations for polyacids: Significance of the pK sub a and parameters in the Kern equation

Science.gov (United States)

Meites, L.

1978-01-01

A new method is suggested for calculating the dissociation constants of polyvalent acids, especially polymeric acids. In qualitative form the most significant characteristics of the titration curves are demonstrated and identified which are obtained when titrating the solutions of such acids with a standard base potentiometrically.

Two-phase titration of cerium(3) by permanganate

International Nuclear Information System (INIS)

Lazarev, A.I.; Lazareva, V.I.; Gerko, V.V.

1986-01-01

Reaction of cerium (3) and permanganate was investigated at a room temperature depending on PH, concentrations of pyrophosphate, cerium (3), tetraphenylphosphonium and foreign compounds. Selective method of two-phase titration determination of cerium (3) by permanganate without using silver compounds, preliminary separation of chlorides, nitrates, was developed. The method was tested using alloys based on iron, nickel, REE, copper, cobalt (S r ≤0.008). Correctness is proved with method of standard additives

Utilizing the virus-induced blocking of apoptosis in an easy baculovirus titration method.

Science.gov (United States)

Niarchos, Athanasios; Lagoumintzis, George; Poulas, Konstantinos

2015-10-22

Baculovirus-mediated protein expression is a robust experimental technique for producing recombinant higher-eukaryotic proteins because it combines high yields with considerable post-translational modification capabilities. In this expression system, the determination of the titer of recombinant baculovirus stocks is important to achieve the correct multiplicity of infection for effective amplification of the virus and high expression of the target protein. To overcome the drawbacks of existing titration methods (e.g., plaque assay, real-time PCR), we present a simple and reliable assay that uses the ability of baculoviruses to block apoptosis in their host cells to accurately titrate virus samples. Briefly, after incubation with serial dilutions of baculovirus samples, Sf9 cells were UV irradiated and, after apoptosis induction, they were viewed via microscopy; the presence of cluster(s) of infected cells as islets indicated blocked apoptosis. Subsequently, baculovirus titers were calculated through the determination of the 50% endpoint dilution. The method is simple, inexpensive, and does not require unique laboratory equipment, consumables or expertise; moreover, it is versatile enough to be adapted for the titration of every virus species that can block apoptosis in any culturable host cells which undergo apoptosis under specific conditions.

Automated spectrophotometric bicarbonate analysis in duodenal juice compared to the back titration method.

Science.gov (United States)

Erchinger, Friedemann; Engjom, Trond; Gudbrandsen, Oddrun Anita; Tjora, Erling; Gilja, Odd H; Dimcevski, Georg

2016-01-01

We have recently evaluated a short endoscopic secretin test for exocrine pancreatic function. Bicarbonate concentration in duodenal juice is an important parameter in this test. Measurement of bicarbonate by back titration as the gold standard method is time consuming, expensive and technically difficult, thus a simplified method is warranted. We aimed to evaluate an automated spectrophotometric method in samples spanning the effective range of bicarbonate concentrations in duodenal juice. We also evaluated if freezing of samples before analyses would affect its results. Patients routinely examined with short endoscopic secretin test suspected to have decreased pancreatic function of various reasons were included. Bicarbonate in duodenal juice was quantified by back titration and automatic spectrophotometry. Both fresh and thawed samples were analysed spectrophotometrically. 177 samples from 71 patients were analysed. Correlation coefficient of all measurements was r = 0.98 (p titration gold standard. This is a major simplification of direct pancreas function testing, and allows a wider distribution of bicarbonate testing in duodenal juice. Extreme values for Bicarbonate concentration achieved by the autoanalyser method have to be interpreted with caution. Copyright © 2016 IAP and EPC. Published by Elsevier India Pvt Ltd. All rights reserved.

A Fixed Flow is More Effective than Titrated Flow during Bubble Nasal CPAP for Respiratory Distress in Preterm Neonates.

Science.gov (United States)

Murki, Srinivas; Das, Ratan Kumar; Sharma, Deepak; Kumar, Praveen

2015-01-01

The clinical effects of a pre-fixed flow of air-oxygen versus a flow titrated according to visible bubbling are not well understood. To compare the effects of a fixed flow (5 L/min) and titrated flow (flow just enough to ensure bubbling) at different set pressures on delivered intra-prong pressure, gas exchange and clinical parameters in preterm infants on bubble CPAP for respiratory distress. Preterm infants rate, set pressure, FiO2, SpO2, Silverman retraction score, respiratory rate, abdominal girth, and blood gases were recorded. The delivered intra-prong pressure was measured by an electronic manometer. 69 recordings were made in 54 infants. For each of the set CPAP pressures (4, 5, and 6 cm H2O), the mean delivered pressure with a fixed flow of 5 L/min was higher than that delivered by the titrated flow. During the fixed flow epoch, the delivered pressure was closer to and higher than the set pressure resulting in higher PaO2 and lower PaCO2 as compared to titrated flow epoch. In the titrated flow period, the delivered pressure was consistently lower than the set pressure. In preterm infants on bubble CPAP with set pressures of 4-6 cm H2O, a fixed flow of 5 L/min is more effective than a flow titrated to ensure adequate visible bubbling. It achieves higher delivered pressures, better oxygenation and ventilation.

Prediction of vapor pressure and heats of vaporization of edible oil/fat compounds by group contribution

DEFF Research Database (Denmark)

Ceriani, Roberta; Gani, Rafiqul; Liu, Y.A.

2013-01-01

In the present work, a group contribution method is proposed for the estimation of vapor pressures and heats of vaporization of organic liquids found in edible fat/oil and biofuel industries as a function of temperature. The regression of group contribution parameters was based on an extensive...

Concentration determination of methyl magnesium chloride and other Grignard reagents by potentiometric titration with in-line characterization of reaction species by FTIR spectroscopy.

Science.gov (United States)

Chen, Yadan; Wang, Tao; Helmy, Roy; Zhou, George X; LoBrutto, Rosario

2002-07-01

A potentiometric titration method for methyl magnesium chloride and other Grignard reagents based on the reaction with 2-butanol in THF has been developed and validated. The method employs a commercially available platinum electrode, using an electrolyte compatible with non-aqueous solvents. Well-defined titration curves were obtained, along with excellent method precision. The endpoint was precisely determined based on the first derivative of the titration curve. Different solvents such as THF, diethyl ether and methylene chloride provided similar results with regard to sharpness of the endpoint and method precision. The method was applied to a wide array of Grignard reagents including methyl magnesium bromide, ethyl magnesium chloride, propyl magnesium chloride, vinyl magnesium chloride, phenyl magnesium chloride, and benzyl magnesium chloride with similar precision and accuracy. Application of in-line FTIR was demonstrated for in situ monitoring of the titration reaction, allowing characterization of the reaction species. An authentic spectrum of the MeMgCl-THF complex was obtained using spectral subtraction and the vibrational absorbance bands were identified. FTIR also provided an alternative for detecting the titration endpoint, and the titration results so obtained, provided a cross-validation of the accuracy of the potentiometric titration.

Stepwise thermometric titration of free acid and uranyl with single reagent

International Nuclear Information System (INIS)

Zamek, M.

1976-01-01

The determination is based on the titration of 0.2-1 M Na 2 B 4 O 7 or Li 2 B 4 O 7 at a rate of 2.10 -6 -10 -5 equiv./s. The exothermal reaction H + +OH - =H 2 O is followed by the formation of polynuclear complexes, accompanied by the drop in the temperature of the reaction mixture. The break in the titration curve corresponds to the defined relation UO 2 2+ :OH - (7:3). It is thus possible to determine U also in the organic phase following the extraction of tributylphosphate from an acid medium. The determination is disturbed by easily hydrolyzable ions. The accuracy and correctness of the method is between 0.1-3%. depending on the concentrations of the determined components up to the molar ratio UO 2 2+ : acid 1:100. (M.K.)

Functionalized carbon nanotubes containing isocyanate groups

International Nuclear Information System (INIS)

Zhao Chungui; Ji Lijun; Liu Huiju; Hu Guangjun; Zhang Shimin; Yang Mingshu; Yang Zhenzhong

2004-01-01

Functionalized carbon nanotubes containing isocyanate groups can extend the nanotube chemistry, and may promote their many potential applications such as in polymer composites and coatings. This paper describes a facile method to prepare functionalized carbon nanotubes containing highly reactive isocyanate groups on its surface via the reaction between toluene 2,4-diisocyanate and carboxylated carbon nanotubes. Fourier-transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed that reactive isocyanate groups were covalently attached to carbon nanotubes. The content of isocyanate groups were determined by chemical titration and thermogravimetric analysis (TGA)

Titulador potenciométrico automatizado baseado em sistema de fluxo monossegmentado Automated potentiometric titrator based in monosegmented flow system

Directory of Open Access Journals (Sweden)

Edgard Moreira Ganzarolli

1999-02-01

Full Text Available A new automated system for acid-base flow titrations is proposed. In the operation mode, several sample to titrant volumetric ratios are injected in an air segmented plug. Five three way solenoid valves and three acrilic junctions, assembled in a hidrodynamic injection system, were accountable for the monosegmented reagents plug formation. A turbulent flow reactor was used for a perfect mix of reagents in the plug. The detector system employed a glass combined electrode fitted in an acrilic holder. Titrations of hydrochloric, nitric and acetic acids, in several concentrations, were performed with standard sodium hidroxide, for evaluation of the efficiency of the system. The relative standard deviation of the determinations was about ±0,5% and each titration was carried out in 3-4 minutes. A Quick BASIC 4.5® program was developed for the titrator control.

Macromolecular Competition Titration Method: Accessing Thermodynamics of the Unmodified Macromolecule–Ligand Interactions Through Spectroscopic Titrations of Fluorescent Analogs

Science.gov (United States)

Bujalowski, Wlodzimierz; Jezewska, Maria J.

2011-01-01

Analysis of thermodynamically rigorous binding isotherms provides fundamental information about the energetics of the ligand–macromolecule interactions and often an invaluable insight about the structure of the formed complexes. The Macromolecular Competition Titration (MCT) method enables one to quantitatively obtain interaction parameters of protein–nucleic acid interactions, which may not be available by other methods, particularly for the unmodified long polymer lattices and specific nucleic acid substrates, if the binding is not accompanied by adequate spectroscopic signal changes. The method can be applied using different fluorescent nucleic acids or fluorophores, although the etheno-derivatives of nucleic acid are especially suitable as they are relatively easy to prepare, have significant blue fluorescence, their excitation band lies far from the protein absorption spectrum, and the modification eliminates the possibility of base pairing with other nucleic acids. The MCT method is not limited to the specific size of the reference nucleic acid. Particularly, a simple analysis of the competition titration experiments is described in which the fluorescent, short fragment of nucleic acid, spanning the exact site-size of the protein–nucleic acid complex, and binding with only a 1:1 stoichiometry to the protein, is used as a reference macromolecule. Although the MCT method is predominantly discussed as applied to studying protein–nucleic acid interactions, it can generally be applied to any ligand–macromolecule system by monitoring the association reaction using the spectroscopic signal originating from the reference macromolecule in the presence of the competing macromolecule, whose interaction parameters with the ligand are to be determined. PMID:21195223

Macromolecular competition titration method accessing thermodynamics of the unmodified macromolecule-ligand interactions through spectroscopic titrations of fluorescent analogs.

Science.gov (United States)

Bujalowski, Wlodzimierz; Jezewska, Maria J

2011-01-01

Analysis of thermodynamically rigorous binding isotherms provides fundamental information about the energetics of the ligand-macromolecule interactions and often an invaluable insight about the structure of the formed complexes. The Macromolecular Competition Titration (MCT) method enables one to quantitatively obtain interaction parameters of protein-nucleic acid interactions, which may not be available by other methods, particularly for the unmodified long polymer lattices and specific nucleic acid substrates, if the binding is not accompanied by adequate spectroscopic signal changes. The method can be applied using different fluorescent nucleic acids or fluorophores, although the etheno-derivatives of nucleic acid are especially suitable as they are relatively easy to prepare, have significant blue fluorescence, their excitation band lies far from the protein absorption spectrum, and the modification eliminates the possibility of base pairing with other nucleic acids. The MCT method is not limited to the specific size of the reference nucleic acid. Particularly, a simple analysis of the competition titration experiments is described in which the fluorescent, short fragment of nucleic acid, spanning the exact site-size of the protein-nucleic acid complex, and binding with only a 1:1 stoichiometry to the protein, is used as a reference macromolecule. Although the MCT method is predominantly discussed as applied to studying protein-nucleic acid interactions, it can generally be applied to any ligand-macromolecule system by monitoring the association reaction using the spectroscopic signal originating from the reference macromolecule in the presence of the competing macromolecule, whose interaction parameters with the ligand are to be determined. Copyright © 2011 Elsevier Inc. All rights reserved.

Three different up-titration regimens of ponesimod, an S1P1 receptor modulator, in healthy subjects.

Science.gov (United States)

Scherz, Michael W; Brossard, Patrick; D'Ambrosio, Daniele; Ipek, Murat; Dingemanse, Jasper

2015-06-01

Ponesimod is a selective S1P1 receptor modulator, and induces dose-dependent reduction of circulating lymphocytes upon oral dosing. Previous studies showed that single doses up to 75 mg or multiple doses up to 40 mg once daily are well tolerated, and heart rate (HR) reduction and atrio-ventricular conduction delays upon treatment initiation are reduced by gradual up-titration to the maintenance dose. This single-center, open-label, randomized, multiple-dose, 3-treatment, 3-way crossover study compared the tolerability, safety, pharmacokinetics, cardiodynamics, and effects on lymphocytes of 3 different up-titration regimens of ponesimod in healthy male and female subjects. Up-titration regimens comprised escalating periods of b.i.d. dosing (2.5 or 5 mg) and q.d. dosing (10 or 20 mg or both). After the third up-titration period a variable-duration washout period of 1-3 days was followed by re-challenge with a single 20-mg dose of ponesimod. Adverse events were transient and mild to moderate in intensity, not different between regimens. HR decrease after the first dose was greater than after all subsequent doses, including up-titration doses. Little or no HR change was observed with morning doses of b.i.d. regimens, suggesting that 2.5 and 5 mg b.i.d. are sufficient to sustain cardiac desensitization for the 12-hours dosing interval. © 2015, The American College of Clinical Pharmacology.

Factors Contributing to Student Engagement in an Instructional Facebook Group for Undergraduate Mathematics

Science.gov (United States)

Gregory, Peter L.; Gregory, Karen M.; Eddy, Erik R.

2016-01-01

This study investigates factors contributing to student engagement in an educational Facebook group. The study is based on survey results of 138 undergraduate mathematics students at a highly diverse urban public university. Survey measures included engagement in the Facebook group, access to Facebook, comfort using technology, and interest in the…

Process synthesis, design and analysis using a process-group contribution method

DEFF Research Database (Denmark)

Kumar Tula, Anjan; Eden, Mario R.; Gani, Rafiqul

2015-01-01

) techniques. The fundamental pillars of this framework are the definition and use of functional process-groups (building blocks) representing a wide range of process operations, flowsheet connectivity rules to join the process-groups to generate all the feasible flowsheet alternatives and flowsheet property...... models like energy consumption, atom efficiency, environmental impact to evaluate the performance of the generated alternatives. In this way, a list of feasible flowsheets are quickly generated, screened and selected for further analysis. Since the flowsheet is synthesized and the operations......This paper describes the development and application of a process-group contribution method to model, simulate and synthesize chemical processes. Process flowsheets are generated in the same way as atoms or groups of atoms are combined to form molecules in computer aided molecular design (CAMD...

A modified two-point titration method for the determination of volatile fatty acids in anaerobic systems.

Science.gov (United States)

Mu, Zhe-Xuan; He, Chuan-Shu; Jiang, Jian-Kai; Zhang, Jie; Yang, Hou-Yun; Mu, Yang

2018-04-10

The volatile fatty acids (VFA) concentration plays important roles in the rapid start-up and stable operation of anaerobic reactors. It's essential to develop a simple and accurate method to monitor the VFA concentration in the anaerobic systems. In present work, a modified two-point titration method was developed to determine the VFA concentration. The results show that VFA concentration in standard solutions estimated by the titration method coincided well with that measured by gas chromatograph, where all relative errors were lower than 5.5%. Compared with the phosphate, ammonium and sulfide subsystems, the effect of bicarbonate on the accuracy of the developed method was relatively significant. When the bicarbonate concentration varied from 0 to 8 mmol/L, the relative errors increased from 1.2% to 30% for VFA concentration at 1 mmol/L, but were within 2.0% for that at 5 mmol/L. In addition, the VFA composition affected the accuracy of the titration method to some extent. This developed titration method was further proved to be effective with practical effluents from a lab-scale anaerobic reactor under organic shock loadings and an unstable full-scale anaerobic reactor. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thermometric titration of thorium with EDTA in the presence of large excess of neutral sodium salts.

Science.gov (United States)

Doi, K

1980-11-01

The thermometric titration of Th(IV) in the presence of neutral sodium salts, sulphuric acid or acetic acid with EDTA has been studied. The effect of each on the observed heat values for the titration is discussed. For sodium perchlorate media, DeltaH values of -9 and -21 kJ/mole have been estimated for the formation of the Th(IV)-EDTA chelate at mu --> 0 and mu = 0.5 (NaClO(4)), respectively. The -DeltaH values increase steadily with increase in concentration of sodium perchlorate up to at least 3M. For the titration of Th(IV) in the presence of a large excess of sodium nitrate the use of sodium iodide as a masking reagent has been examined: large amounts of Bi and Cu(II) are masked and a masking effect is observed for small amounts of Ni.

Haemoglobins with multiple reactive sulfhydryl groups: reactions of ...

African Journals Online (AJOL)

The pH dependence profile of kapp for the slow phase resembles the titration curve of a monoprotic acid. Quantitative analysis indicates that the sulfhydryl group to which this phase may be attributed is linked to a single ionizable group with a pKa of 6.1 0.2. Examination of the structure of guinea pig haemoglobin near the ...

Haemoglobins with multiple reactive sulfhydryl groups: reactions of ...

African Journals Online (AJOL)

The pH dependence profile of kapp, the apparent second-order rate constant, for the fast phase resembles the titration curve of a diprotic acid. Quantitative analysis indicates that the reactivity of the sulfhydryl group to which this phase may be attributed is linked to two ionizable groups with pKas of 6.4 0.1 and 7.8 0.2.

An open-label Optional Titration Trial to Evaluate the Efficacy ...

African Journals Online (AJOL)

An eight-week open-label optional titration trial to evaluate the efficacy, tolerability and safety of Valsartan 80 mg/ & 160 mg once daily was carried out in patients with mild to moderate essential hypertension at the Lagos University Teaching Hospital. There was a significant reduction in both systolic and diastolic blood ...

Avian influenza virus isolation, propagation and titration in embryonated chicken eggs

Science.gov (United States)

Avian influenza (AI) virus is usually isolated, propagated, and titrated in embryonated chickens eggs (ECE). Most any sample type can be accommodated for culture with appropriate processing. Isolation may also be accomplished in cell culture particularly if mammalian lineage isolates are suspected, ...

Titration of Monoprotic Acids with Sodium Hydroxide Contaminated by Sodium Carbonate.

Science.gov (United States)

Michalowski, Tadeusz

1988-01-01

Discusses the effects of using carbon dioxide contaminated sodium hydroxide solution as a titrant for a solution of a weak monoprotic acid and the resulting distortion of the titration curve in comparison to one obtained when an uncontaminated titrant is used. (CW)

Higher Order Inclusion Complexes and Secondary Interactions Studied by Global Analysis of Calorimetric Titrations

DEFF Research Database (Denmark)

Schönbeck, Jens Christian Sidney; Holm, René; Westh, Peter

2012-01-01

This paper investigates the use of isothermal titration calorimetry (ITC) as a tool for studying molecular systems in which weaker secondary interactions are present in addition to a dominant primary interaction. Such systems are challenging since the signal pertaining to the stronger primary......). The results are validated by a 13C NMR titration and negative controls with a bile salt with no secondary binding site (glycocholate) (K = 2.96 ± 0.01 × 103 M–1). The method proved useful for detailed analysis of ITC data and may strengthen its use as a tool for studying molecular systems by advanced binding...

Determination of the point-of-zero, charge of manganese oxides with different methods including an improved salt titration method

NARCIS (Netherlands)

Tan, W.F.; Lu, S.J.; Liu, F.; Feng, X.H.; He, J.Z.; Koopal, L.K.

2008-01-01

Manganese (Mn) oxides are important components in soils and sediments. Points-of-zero charge (PZC) of three synthetic Mn oxides (birnessite, cryptomelane, and todorokite) were determined by using three classical techniques (potentiometric titration or PT, rapid PT or R-PT, and salt titration or ST)

Development and Analysis of Group Contribution Plus Models for Property Prediction of Organic Chemical Systems

DEFF Research Database (Denmark)

Mustaffa, Azizul Azri

for the GIPs are then used in the UNIFAC model to calculate activity coefficients. This approach can increase the application range of any “host” UNIFAC model by providing a reliable predictive model towards fast and efficient product development. This PhD project is focused on the analysis and further......Prediction of properties is important in chemical process-product design. Reliable property models are needed for increasingly complex and wider range of chemicals. Group-contribution methods provide useful tool but there is a need to validate them and improve their accuracy when complex chemicals...... are present in the mixtures. In accordance with that, a combined group-contribution and atom connectivity approach that is able to extend the application range of property models has been developed for mixture properties. This so-called Group-ContributionPlus (GCPlus) approach is a hybrid model which combines...

Elucidation of the electronic spectrum changes of KA-Al3+ complex by potentiometric titration, FTIR, 13C NMR and quantum mechanics

International Nuclear Information System (INIS)

Piantavini, Mário S.; Gonçalves, Alan G.; Trindade, Ângela C.L.B.; Noseda, Miguel D.; Mercê, Ana L.R.; Pontarolo, Roberto; Machado, Antonio E.H.

2017-01-01

Kojic acid (KA) is an organic acid widely used in pharmaceutical industry, mainly as a skin lightening agent. Based on the ability of KA to form complexes with ions, we found the most possible kind of complex formed with cation aluminum. KA-Al 3+ complex structures were studied using potentiometric and spectrophotometric (UV) titrations, FTIR and 13 C NMR. The electronic spectroscopy showed that the KA-Al 3+ complexes absorb at higher wavelengths (λ max = 305 nm) than do the non-complexed KA (λ max = 269 nm), confirming complexation. The IR spectra of KA complexed and not complexed allowed to correlate the changes in the absorption of enol and carbonyl groups in absence and presence of Al 3+ in aqueous solutions. The complexation suggested by the potentiometric titration and FTIR spectroscopy are in accordance with the data obtained from NMR results. Calculations based on quantum mechanics were utilized to understand the differences found in the non complexed and complexed KAH electronic spectra. (author)

A digital image-based method for determining of total acidity in red wines using acid-base titration without indicator.

Science.gov (United States)

Tôrres, Adamastor Rodrigues; Lyra, Wellington da Silva; de Andrade, Stéfani Iury Evangelista; Andrade, Renato Allan Navarro; da Silva, Edvan Cirino; Araújo, Mário César Ugulino; Gaião, Edvaldo da Nóbrega

2011-05-15

This work proposes the use of digital image-based method for determination of total acidity in red wines by means of acid-base titration without using an external indicator or any pre-treatment of the sample. Digital images present the colour of the emergent radiation which is complementary to the radiation absorbed by anthocyanines present in wines. Anthocyanines change colour depending on the pH of the medium, and from the variation of colour in the images obtained during titration, the end point can be localized with accuracy and precision. RGB-based values were employed to build titration curves, and end points were localized by second derivative curves. The official method recommends potentiometric titration with a NaOH standard solution, and sample dilution until the pH reaches 8.2-8.4. In order to illustrate the feasibility of the proposed method, titrations of ten red wines were carried out. Results were compared with the reference method, and no statistically significant difference was observed between the results by applying the paired t-test at the 95% confidence level. The proposed method yielded more precise results than the official method. This is due to the trivariate nature of the measurements (RGB), associated with digital images. Copyright © 2011 Elsevier B.V. All rights reserved.

Differential electrolytic potentiometric titration method for the determination of ciprofloxacin in drug formulations.

Science.gov (United States)

Abulkibash, Abdalla M; Sultan, Salah M; Al-Olyan, Abeer M; Al-Ghannam, Sheikha M

2003-10-17

A simple and rapid differential electrolytic potentiometric titration method for the determination of ciprofloxacin was developed. The work is based on the fast complexation reaction between iron(III) and ciprofloxacin in a ratio of 1:3, respectively, in sulfuric acid media of 0.09 mol dm(-3). Among the electrodes tested silver amalgam electrodes were found to be a suitable indicating system. By applying a current density of 0.5 muA cm(-2) to these electrodes and using iron(III) solution of 0.097 mol dm(-3) as a titrant, normal titration curves were obtained. The method was successfully applied for the determination of ciprofloxacin in drug formulations as low as 4.0 ppm.

AMDTreat 5.0+ with PHREEQC titration module to compute caustic chemical quantity, effluent quality, and sludge volume

Science.gov (United States)

Cravotta, Charles A.; Means, Brent P; Arthur, Willam; McKenzie, Robert M; Parkhurst, David L.

2015-01-01

Alkaline chemicals are commonly added to discharges from coal mines to increase pH and decrease concentrations of acidity and dissolved aluminum, iron, manganese, and associated metals. The annual cost of chemical treatment depends on the type and quantities of chemicals added and sludge produced. The AMDTreat computer program, initially developed in 2003, is widely used to compute such costs on the basis of the user-specified flow rate and water quality data for the untreated AMD. Although AMDTreat can use results of empirical titration of net-acidic or net-alkaline effluent with caustic chemicals to accurately estimate costs for treatment, such empirical data are rarely available. A titration simulation module using the geochemical program PHREEQC has been incorporated with AMDTreat 5.0+ to improve the capability of AMDTreat to estimate: (1) the quantity and cost of caustic chemicals to attain a target pH, (2) the chemical composition of the treated effluent, and (3) the volume of sludge produced by the treatment. The simulated titration results for selected caustic chemicals (NaOH, CaO, Ca(OH)2, Na2CO3, or NH3) without aeration or with pre-aeration can be compared with or used in place of empirical titration data to estimate chemical quantities, treated effluent composition, sludge volume (precipitated metals plus unreacted chemical), and associated treatment costs. This paper describes the development, evaluation, and potential utilization of the PHREEQC titration module with the new AMDTreat 5.0+ computer program available at http://www.amd.osmre.gov/.

Origin of two time-scale regimes in potentiometric titration of metal oxides. A replica kinetic Monte Carlo study

International Nuclear Information System (INIS)

Zarzycki, Piotr P.; Rosso, Kevin M.

2009-01-01

Replica Kinetic Monte Carlo simulations were used to study the characteristic time scales of potentiometric titration of the metal oxides and (oxy)hydroxides. The effect of surface heterogeneity and surface transformation on the titration kinetics were also examined. Two characteristic relaxation times are often observed experimentally, with the trailing slower part attributed to surface non-uniformity, porosity, polymerization, amorphization, and other dynamic surface processes induced by unbalanced surface charge. However, our simulations show that these two characteristic relaxation times are intrinsic to the proton binding reaction for energetically homogeneous surfaces, and therefore surface heterogeneity or transformation do not necessarily need to be invoked. However, all such second-order surface processes are found to intensify the separation and distinction of the two kinetic regimes. The effect of surface energetic-topographic non-uniformity, as well dynamic surface transformation, interface roughening/smoothing were described in a statistical fashion. Furthermore, our simulations show that a shift in the point-of-zero charge is expected from increased titration speed and the pH-dependence of the titration measurement error is in excellent agreement with experimental studies.

Origin of two time-scale regimes in potentiometric titration of metal oxides. A replica kinetic Monte Carlo study.

Science.gov (United States)

Zarzycki, Piotr; Rosso, Kevin M

2009-06-16

Replica kinetic Monte Carlo simulations were used to study the characteristic time scales of potentiometric titration of the metal oxides and (oxy)hydroxides. The effect of surface heterogeneity and surface transformation on the titration kinetics were also examined. Two characteristic relaxation times are often observed experimentally, with the trailing slower part attributed to surface nonuniformity, porosity, polymerization, amorphization, and other dynamic surface processes induced by unbalanced surface charge. However, our simulations show that these two characteristic relaxation times are intrinsic to the proton-binding reaction for energetically homogeneous surfaces, and therefore surface heterogeneity or transformation does not necessarily need to be invoked. However, all such second-order surface processes are found to intensify the separation and distinction of the two kinetic regimes. The effect of surface energetic-topographic nonuniformity, as well dynamic surface transformation, interface roughening/smoothing were described in a statistical fashion. Furthermore, our simulations show that a shift in the point-of-zero charge is expected from increased titration speed, and the pH-dependence of the titration measurement error is in excellent agreement with experimental studies.

Non-euclidean simplex optimization. [Application to potentiometric titration of Pu

Energy Technology Data Exchange (ETDEWEB)

Silver, G.L.

1977-08-15

Geometric optimization techniques useful for studying chemical equilibrium traditionally rely upon principles of euclidean geometry, but such algorithms may also be based upon principles of a non-euclidean geometry. The sequential simplex method is adapted to the hyperbolic plane, and application of optimization to problems such as the potentiometric titration of plutonium is suggested.

Subsite binding energies of an exo-polygalacturonase using isothermal titration calorimetry

Science.gov (United States)

Thermodynamic parameters for binding of a series of galacturonic acid oligomers to an exo-polygalacturonase, RPG16 from Rhizopus oryzae, were determined by isothermal titration calorimetry. Binding of oligomers varying in chain length from two to five galacturonic acid residues is an exothermic proc...

The possibility of determining the activity coefficients of individual ions from acid-base titration data

Science.gov (United States)

Jano, I.; Hardcastle, J. E.

1998-07-01

A method is described for obtaining the activity coefficients of individual ions from experimental titration data. For this purpose, a general polyprotic acid-base-titration-curve equation is derived. The equation allows obtaining the dissociation equilibrium constants of the acid and the ratio of the activity coefficient of each ion to the activity coefficient of the undissociated acid directly from the titration data. Results obtained are compared with coefficients calculated using Debye-Hückel equation. A general equation relating the ionic strength to the pH of the titration medium is also established. Une méthode pour l'obtention des coefficients d'activité des ions individuels à partir des données expérimentales de titrage est établie. À ce but, une équation générale est dérivée pour représenter la courbe de titrage d'un acide avec une base. Cette équation permet d'obtenir les constants d'équilibre de dissociation de l'acide et le rapport de coefficient d'activité de chaque ion au coefficient d'activité de l'acide non-dissocié à partir des données de titrage. Les résultats ainsi obtenus sont comparés avec les coefficients calculés à l'aide de l'équation de Debye-Hückel. Une équation liant la force ionique au pH du milieu est établie aussi.

Dissecting electrostatic interactions in Bacillus circulans xylanase through NMR-monitored pH titrations

Energy Technology Data Exchange (ETDEWEB)

McIntosh, Lawrence P., E-mail: mcintosh@chem.ubc.ca; Naito, Daigo; Baturin, Simon J.; Okon, Mark; Joshi, Manish D. [University of British Columbia, Department of Biochemistry and Molecular Biology, Department of Chemistry, and Michael Smith Laboratories, Life Sciences Centre (Canada); Nielsen, Jens E. [University College Dublin, School of Biomolecular and Biomedical Science, Centre for Synthesis and Chemical Biology, UCD Conway Institute (Ireland)

2011-09-15

NMR-monitored pH titration curves of proteins provide a rich source of structural and electrostatic information. Although relatively straightforward to measure, interpreting pH-dependent chemical shift changes to obtain site-specific acid dissociation constants (pK{sub A} values) is challenging. In order to analyze the biphasic titrations exhibited by the side chain {sup 13}C{sup {gamma}} nuclei of the nucleophilic Glu78 and general acid/base Glu172 in Bacillus circulans xylanase, we have revisited the formalism for the ionization equilibria of two coupled acidic residues. In general, fitting NMR-monitored pH titration curves for such a system will only yield the two macroscopic pK{sub A} values that reflect the combined effects of both deprotonation reactions. However, through the use of mutations complemented with ionic strength-dependent measurements, we are able to extract the four microscopic pK{sub Ai} values governing the branched acid/base equilibria of Glu78 and Glu172 in BcX. These data, confirmed through theoretical calculations, help explain the pH-dependent mechanism of this model GH11 xylanase by demonstrating that the kinetically determined pK{sub A} values and hence catalytic roles of these two residues result from their electrostatic coupling.

Dissecting electrostatic interactions in Bacillus circulans xylanase through NMR-monitored pH titrations

International Nuclear Information System (INIS)

McIntosh, Lawrence P.; Naito, Daigo; Baturin, Simon J.; Okon, Mark; Joshi, Manish D.; Nielsen, Jens E.

2011-01-01

NMR-monitored pH titration curves of proteins provide a rich source of structural and electrostatic information. Although relatively straightforward to measure, interpreting pH-dependent chemical shift changes to obtain site-specific acid dissociation constants (pK A values) is challenging. In order to analyze the biphasic titrations exhibited by the side chain 13 C γ nuclei of the nucleophilic Glu78 and general acid/base Glu172 in Bacillus circulans xylanase, we have revisited the formalism for the ionization equilibria of two coupled acidic residues. In general, fitting NMR-monitored pH titration curves for such a system will only yield the two macroscopic pK A values that reflect the combined effects of both deprotonation reactions. However, through the use of mutations complemented with ionic strength-dependent measurements, we are able to extract the four microscopic pK Ai values governing the branched acid/base equilibria of Glu78 and Glu172 in BcX. These data, confirmed through theoretical calculations, help explain the pH-dependent mechanism of this model GH11 xylanase by demonstrating that the kinetically determined pK A values and hence catalytic roles of these two residues result from their electrostatic coupling.

Acid-base properties of humic substances from composted and thermally-dried sewage sludges and amended soils as determined by potentiometric titration and the NICA-Donnan model.

Science.gov (United States)

Fernández, José M; Plaza, César; Senesi, Nicola; Polo, Alfredo

2007-09-01

The acid-base properties of humic acids (HAs) and fulvic acids (FAs) isolated from composted sewage sludge (CS), thermally-dried sewage sludge (TS), soils amended with either CS or TS at a rate of 80 t ha(-1)y(-1) for 3y and the corresponding unamended soil were investigated by use of potentiometric titrations. The non-ideal competitive adsorption (NICA)-Donnan model for a bimodal distribution of proton binding sites was fitted to titration data by use of a least-squares minimization method. The main fitting parameters of the NICA-Donnan model obtained for each HA and FA sample included site densities, median affinity constants and widths of affinity distributions for proton binding to low and high affinity sites, which were assumed to be, respectively, carboxylic- and phenolic-type groups. With respect to unamended soil HA and FA, the HAs and FAs from CS, and especially TS, were characterized by smaller acidic functional group contents, larger proton binding affinities of both carboxylic- and phenolic-type groups, and smaller heterogeneity of carboxylic and phenolic-type groups. Amendment with CS or TS led to a decrease of acidic functional group contents and a slight increase of proton binding affinities of carboxylic- and phenolic-type groups of soil HAs and FAs. These effects were more evident in the HA and FA fractions from CS-amended soil than in those from TS-amended soil.

Common Standards of Basal Insulin Titration in T2DM

Science.gov (United States)

Arnolds, Sabine; Heise, Tim; Flacke, Frank; Sieber, Jochen

2013-01-01

Type 2 diabetes mellitus has become a worldwide major health problem, and the number of people affected is steadily increasing. Thus, not all patients suffering from the disease can be treated by specialized diabetes centers or outpatient clinics, but by primary care physicians. The latter, however, might have time constraints and have to deal with many kinds of diseases or with multimorbid patients, so their focus is not so much on lowering high blood glucose values. Thus, the physicians, as well as the patients themselves, are often reluctant to initiate and adjust insulin therapy, although basal insulin therapy is considered the appropriate strategy after oral antidiabetic drug failure, according to the latest international guidelines. A substantial number of clinical studies have shown that insulin initiation and optimization can be managed successfully by using titration algorithms—even in cases where patients themselves are the drivers of insulin titration. Nevertheless, tools and strategies are needed to facilitate this process in the daily life of both primary health care professionals and patients with diabetes. PMID:23759411

Potential benefits of slow titration of paroxetine treatment in an elderly population: eight-week results from a naturalistic setting.

Science.gov (United States)

Gibiino, Sara; Mori, Elisa; De Ronchi, Diana; Serretti, Alessandro

2013-08-01

Late-life depression, often in association with anxiety, affects approximately 15% of individuals older than 65 years. Selective serotonin reuptake inhibitors are the first-line treatment but could be responsible of an early exacerbation of anxiety, possibly reduced by a very gradual titration of drugs. The main aim of this study is to compare gradual and rapid (standard) titration of paroxetine in an elderly population. In a naturalistic setting, 50 elderly (≥60 years old) outpatients with unipolar mood disorder or anxiety disorder were naturalistically assigned to abrupt initiation of 10 mg of paroxetine or to a gradual increase with 2.5 mg on alternate days up to 10 mg in 7 days. Then dosage could be maintained at 10 mg or increased according to clinical response. Primary outcome was efficacy as assessed by the Hamilton Depression Rating Scale (HAM-D) 21, HAM-D symptom subscales (core, psychic anxiety, somatic anxiety cluster), and Hamilton Anxiety Rating Scale changes. Secondary outcome was evaluation of overall dropouts at eighth week and evaluation of most common adverse effects through the global judgment of the Dosage Record and Treatment Emergent Symptom Scale. All data were recorded weekly for the first 8 weeks of treatment (with 1 more evaluation after 3 days from the baseline). Samples were comparable at baseline, with patients in gradual titration showing a higher level of psychic anxiety. During the first 3 days of treatment, a significant worsening in psychic anxiety was observed in patients treated abruptly with 10 mg of paroxetine (difference in HAM-D psychic anxiety subscale from baseline: 110.61% vs 89.38% with rapid and slow titration, respectively; t test P = 0.03). Overall, a significantly greater improvement in depressive and anxious symptoms favored gradual titration (HAM-D core cluster and HAM-D psychic anxiety cluster, respectively, P = 0.014 and P titration). Our results suggest that a gradual titration of paroxetine could avoid the

Accuracy and precision of protein–ligand interaction kinetics determined from chemical shift titrations

International Nuclear Information System (INIS)

Markin, Craig J.; Spyracopoulos, Leo

2012-01-01

NMR-monitored chemical shift titrations for the study of weak protein–ligand interactions represent a rich source of information regarding thermodynamic parameters such as dissociation constants (K D ) in the micro- to millimolar range, populations for the free and ligand-bound states, and the kinetics of interconversion between states, which are typically within the fast exchange regime on the NMR timescale. We recently developed two chemical shift titration methods wherein co-variation of the total protein and ligand concentrations gives increased precision for the K D value of a 1:1 protein–ligand interaction (Markin and Spyracopoulos in J Biomol NMR 53: 125–138, 2012). In this study, we demonstrate that classical line shape analysis applied to a single set of 1 H– 15 N 2D HSQC NMR spectra acquired using precise protein–ligand chemical shift titration methods we developed, produces accurate and precise kinetic parameters such as the off-rate (k off ). For experimentally determined kinetics in the fast exchange regime on the NMR timescale, k off ∼ 3,000 s −1 in this work, the accuracy of classical line shape analysis was determined to be better than 5 % by conducting quantum mechanical NMR simulations of the chemical shift titration methods with the magnetic resonance toolkit GAMMA. Using Monte Carlo simulations, the experimental precision for k off from line shape analysis of NMR spectra was determined to be 13 %, in agreement with the theoretical precision of 12 % from line shape analysis of the GAMMA simulations in the presence of noise and protein concentration errors. In addition, GAMMA simulations were employed to demonstrate that line shape analysis has the potential to provide reasonably accurate and precise k off values over a wide range, from 100 to 15,000 s −1 . The validity of line shape analysis for k off values approaching intermediate exchange (∼100 s −1 ), may be facilitated by more accurate K D measurements from NMR

Accuracy and precision of protein-ligand interaction kinetics determined from chemical shift titrations.

Science.gov (United States)

Markin, Craig J; Spyracopoulos, Leo

2012-12-01

NMR-monitored chemical shift titrations for the study of weak protein-ligand interactions represent a rich source of information regarding thermodynamic parameters such as dissociation constants (K ( D )) in the micro- to millimolar range, populations for the free and ligand-bound states, and the kinetics of interconversion between states, which are typically within the fast exchange regime on the NMR timescale. We recently developed two chemical shift titration methods wherein co-variation of the total protein and ligand concentrations gives increased precision for the K ( D ) value of a 1:1 protein-ligand interaction (Markin and Spyracopoulos in J Biomol NMR 53: 125-138, 2012). In this study, we demonstrate that classical line shape analysis applied to a single set of (1)H-(15)N 2D HSQC NMR spectra acquired using precise protein-ligand chemical shift titration methods we developed, produces accurate and precise kinetic parameters such as the off-rate (k ( off )). For experimentally determined kinetics in the fast exchange regime on the NMR timescale, k ( off ) ~ 3,000 s(-1) in this work, the accuracy of classical line shape analysis was determined to be better than 5 % by conducting quantum mechanical NMR simulations of the chemical shift titration methods with the magnetic resonance toolkit GAMMA. Using Monte Carlo simulations, the experimental precision for k ( off ) from line shape analysis of NMR spectra was determined to be 13 %, in agreement with the theoretical precision of 12 % from line shape analysis of the GAMMA simulations in the presence of noise and protein concentration errors. In addition, GAMMA simulations were employed to demonstrate that line shape analysis has the potential to provide reasonably accurate and precise k ( off ) values over a wide range, from 100 to 15,000 s(-1). The validity of line shape analysis for k ( off ) values approaching intermediate exchange (~100 s(-1)), may be facilitated by more accurate K ( D ) measurements

The Mobile Insulin Titration Intervention (MITI) for Insulin Adjustment in an Urban, Low-Income Population: Randomized Controlled Trial.

Science.gov (United States)

Levy, Natalie; Moynihan, Victoria; Nilo, Annielyn; Singer, Karyn; Bernik, Lidia S; Etiebet, Mary-Ann; Fang, Yixin; Cho, James; Natarajan, Sundar

2015-07-17

Diabetes patients are usually started on a low dose of insulin and their dose is adjusted or "titrated" according to their blood glucose levels. Insulin titration administered through face-to-face visits with a clinician can be time consuming and logistically burdensome for patients, especially those of low socioeconomic status (SES). Given the wide use of mobile phones among this population, there is the potential to use short message service (SMS) text messaging and phone calls to perform insulin titration remotely. The goals of this pilot study were to (1) evaluate if our Mobile Insulin Titration Intervention (MITI) intervention using text messaging and phone calls was effective in helping patients reach their optimal insulin glargine dose within 12 weeks, (2) assess the feasibility of the intervention within our clinic setting and patient population, (3) collect data on the cost savings associated with the intervention, and (4) measure patient satisfaction with the intervention. This was a pilot study evaluating an intervention for patients requiring insulin glargine titration in the outpatient medical clinic of Bellevue Hospital Center in New York City. Patients in the intervention arm received weekday SMS text messages from a health management platform requesting their fasting blood glucose values. The clinic's diabetes nurse educator monitored the texted responses on the platform website each weekday for alarm values. Once a week, the nurse reviewed the glucose values, consulted the MITI titration algorithm, and called patients to adjust their insulin dose. Patients in the usual care arm continued to receive their standard clinic care for insulin titration. The primary outcome was whether a patient reached his/her optimal insulin glargine dose within 12 weeks. A total of 61 patients consented and were randomized into the study. A significantly greater proportion of patients in the intervention arm reached their optimal insulin glargine dose than patients in

Thermometric titration of thorium with EDTA in the presence of large excess of neutral sodium salts

International Nuclear Information System (INIS)

Doi, K.

1980-01-01

The thermometric titration of Th(IV) in the presence of neutral sodium salts, sulphuric acid or acetic acid with EDT has been studied. The effect of each on the observed heat values for the titration is discussed. For sodium perchlorate media, ΔH values of -9 and -21 kJ/mole have been estimated for the formation of the Th(IV)-EDTA chelate at μ → 0 and μ = 0.5 (NaClO 4 ), respectively. The -ΔH values increase steadily with increase in concentration of sodium perchlorate up to at least 3M. For the titration of Th(IV) in the presence of a large excess of sodium nitrate the use of sodium iodide as a masking reagent has been examined: large amounts of Bi and Cu(II) are masked and a masking effect is observed for small amounts of Ni. (author)

Randomized cross-over trial of ventilator modes during non-invasive ventilation titration in amyotrophic lateral sclerosis.

Science.gov (United States)

Vrijsen, Bart; Buyse, Bertien; Belge, Catharina; Vanpee, Goele; Van Damme, Philip; Testelmans, Dries

2017-08-01

Non-invasive ventilation (NIV) improves survival, quality of life and sleep in patients with amyotrophic lateral sclerosis (ALS). Nevertheless, NIV titration is conducted in different ways. We aim to provide more insight into NIV titration by comparing the effects of a spontaneous (S) and spontaneous-timed (ST) modes on gas exchange, sleep architecture and patient-ventilator asynchronies (PVAs). After an initial night of NIV titration, patients were randomized to S or ST mode in a cross-over design. NIV was titrated using polysomnography, oximetry (oxygen saturation, SpO 2 %) and transcutaneous carbon dioxide (PtcCO 2 ) measurement. PVAs were analysed breath-by-breath. Thirteen patients were analysed after inclusion. ST mode showed better results in gas exchange (minimal SpO 2 %: 83 (80-89)% vs 87 (84-89)%; oxygen desaturation index: 15 (5-28)/h sleep vs 7 (3-9)/h sleep; PtcCO 2 >55 mm Hg: 20 (0-59)% vs 0 (0-27)% total sleep time for S and ST mode, respectively, all P < 0.05) and respiratory events (obstructive: 8.9 (1.2-18.3)/h sleep vs 1.8 (0.3-4.9)/h sleep and central: 2.6 (0.4-14.1)/h sleep vs 0.2 (0.0-1.1)/h sleep for S and ST mode, respectively, both P < 0.01). No differences in sleep architecture were found. Ineffective efforts and respiratory events were more frequently present in S mode. Nevertheless, four patients were discharged on S mode as these patients showed clinically better results for sleep architecture and PVA during the night on S mode. ST mode shows better results in gas exchange, respiratory events and PVA. Nevertheless, accurate NIV titration remains necessary as some patients show equal or better results when using the S mode. © 2017 Asian Pacific Society of Respirology.

Competition over personal resources favors contribution to shared resources in human groups

DEFF Research Database (Denmark)

Barker, Jessie; Barclay, Pat; Reeve, H. Kern

2013-01-01

laboratory economic games with humans, comparing people's investment decisions in games with and without the options to compete over personal resources or invest in a group resource. Our results help explain why people cooperatively contribute to group resources, suggest how a tragedy of the commons may......Members of social groups face a trade-off between investing selfish effort for themselves and investing cooperative effort to produce a shared group resource. Many group resources are shared equitably: they may be intrinsically non-excludable public goods, such as vigilance against predators, or so...... large that there is little cost to sharing, such as cooperatively hunted big game. However, group members' personal resources, such as food hunted individually, may be monopolizable. In such cases, an individual may benefit by investing effort in taking others' personal resources, and in defending one...

The Simulation of an Oxidation-Reduction Titration Curve with Computer Algebra

Science.gov (United States)

Whiteley, Richard V., Jr.

2015-01-01

Although the simulation of an oxidation/reduction titration curve is an important exercise in an undergraduate course in quantitative analysis, that exercise is frequently simplified to accommodate computational limitations. With the use of readily available computer algebra systems, however, such curves for complicated systems can be generated…

Web-based guided insulin self-titration in patients with type 2 diabetes: the Di@log study. Design of a cluster randomised controlled trial [TC1316

Directory of Open Access Journals (Sweden)

Kostense Piet J

2009-06-01

Full Text Available Abstract Background Many patients with type 2 diabetes (T2DM are not able to reach the glycaemic target level of HbA1c Methods/Design T2DM patients (n = 248, aged 35–75 years, with an HbA1c ≥ 7.0%, eligible for treatment with insulin and able to use the internet will be selected from general practices in two different regions in the Netherlands. Cluster randomisation will be performed at the level of general practices. Patients in the intervention group will use a self-developed internet programme to assist them in self-titrating insulin. The control group will receive usual care. Primary outcome is the difference in change in HbA1c between intervention and control group. Secondary outcome measures are quality of life, treatment satisfaction, diabetes self-efficacy and frequency of hypoglycaemic episodes. Results will be analysed according to the intention-to-treat principle. Discussion An internet intervention supporting self-titration of insulin therapy in T2DM patients is an innovative patient-centred intervention. The programme provides guided self-monitoring and evaluation of health and self-care behaviours through tailored feedback on input of glucose values. This is expected to result in a better performance of self-titration of insulin and consequently in the improvement of glycaemic control. The patient will be enabled to 'discover and use his or her own ability to gain mastery over his/her diabetes' and therefore patient empowerment will increase. Based on the self-regulation theory of Leventhal, we hypothesize that additional benefits will be achieved in terms of increases in treatment satisfaction, quality of life and self-efficacy. Trial registration Dutch Trial Register TC1316.

Fluorometric titration approach for calibration of quantity of binding site of purified monoclonal antibody recognizing epitope/hapten nonfluorescent at 340 nm.

Science.gov (United States)

Yang, Xiaolan; Hu, Xiaolei; Xu, Bangtian; Wang, Xin; Qin, Jialin; He, Chenxiong; Xie, Yanling; Li, Yuanli; Liu, Lin; Liao, Fei

2014-06-17

A fluorometric titration approach was proposed for the calibration of the quantity of monoclonal antibody (mcAb) via the quench of fluorescence of tryptophan residues. It applied to purified mcAbs recognizing tryptophan-deficient epitopes, haptens nonfluorescent at 340 nm under the excitation at 280 nm, or fluorescent haptens bearing excitation valleys nearby 280 nm and excitation peaks nearby 340 nm to serve as Förster-resonance-energy-transfer (FRET) acceptors of tryptophan. Titration probes were epitopes/haptens themselves or conjugates of nonfluorescent haptens or tryptophan-deficient epitopes with FRET acceptors of tryptophan. Under the excitation at 280 nm, titration curves were recorded as fluorescence specific for the FRET acceptors or for mcAbs at 340 nm. To quantify the binding site of a mcAb, a universal model considering both static and dynamic quench by either type of probes was proposed for fitting to the titration curve. This was easy for fitting to fluorescence specific for the FRET acceptors but encountered nonconvergence for fitting to fluorescence of mcAbs at 340 nm. As a solution, (a) the maximum of the absolute values of first-order derivatives of a titration curve as fluorescence at 340 nm was estimated from the best-fit model for a probe level of zero, and (b) molar quantity of the binding site of the mcAb was estimated via consecutive fitting to the same titration curve by utilizing such a maximum as an approximate of the slope for linear response of fluorescence at 340 nm to quantities of the mcAb. This fluorometric titration approach was proved effective with one mcAb for six-histidine and another for penicillin G.

Further development of the ceric oxidation ferrous reduction dichromate titration method of plutonium determination

International Nuclear Information System (INIS)

Macdonald, A.; Savage, D.J.

1986-02-01

The chemical reactions involved in the amperometric titration method for plutonium have been further examined, to identify remaining potential sources of bias. As these effects were not expected to be more than 0.1% at the 30 mg plutonium level, a procedure for analysing small (3 mg) aliquots of plutonium has been developed, to help identify any marginal effects. At this reduced level both plutonium and 'blank' determinations indicated that reduction of potassium permanganate by oxalic acid is slower than previously suspected and that a variable small bias can result. Decreasing the concentration of the potassium permanganate eliminated the latter effect. A low bias, proportional to the amount of excess oxalic acid added, was observed. Experiments suggest the bias is due to the reaction of oxalate with an intermediary in the iron II/ dichromate titration. The effect can be adequately reduced by complexing oxalate with cerium III. The reduction of plutonium VI by iron II has been shown to be faster than previously assumed, permitting a decreased waiting time before titration. Minor changes to the original procedure are recommended for analysis of 3 mg aliquots of plutonium. (author)

Novel strategy for generation and titration of recombinant adeno-associated virus vectors.

Science.gov (United States)

Shiau, Ai-Li; Liu, Pu-Ste; Wu, Chao-Liang

2005-01-01

Recombinant adeno-associated virus (rAAV) vectors have many advantages for gene therapeutic applications compared with other vector systems. Several methods that use plasmids or helper viruses have been reported for the generation of rAAV vectors. Unfortunately, the preparation of large-scale rAAV stocks is labor-intensive. Moreover, the biological titration of rAAV is still difficult, which may limit its preclinical and clinical applications. For this study, we developed a novel strategy to generate and biologically titrate rAAV vectors. A recombinant pseudorabies virus (PrV) with defects in its gD, gE, and thymidine kinase genes was engineered to express the AAV rep and cap genes, yielding PS virus, which served as a packaging and helper virus for the generation of rAAV vectors. PS virus was useful not only for generating high-titer rAAV vectors by cotransfection with an rAAV vector plasmid, but also for amplifying rAAV stocks. Notably, the biological titration of rAAV vectors was also feasible when cells were coinfected with rAAV and PS virus. Based on this strategy, we produced an rAAV that expresses prothymosin alpha (ProT). Expression of the ProT protein in vitro and in vivo mediated by rAAV/ProT gene transfer was detected by immunohistochemistry and a bioassay. Taken together, our results demonstrate that the PrV vector-based system is useful for generating rAAV vectors carrying various transgenes.

Acid-base titration of melanocortin peptides: evidence of Trp rotational conformers interconversion.

Science.gov (United States)

Fernandez, Roberto M; Vieira, Renata F F; Nakaie, Clóvis R; Lamy, M Teresa; Ito, Amando S

2005-01-01

Tryptophantime-resolved fluorescence was used to monitor acid-base titration properties of alpha-melanocyte stimulating hormone (alpha-MSH) and the biologically more potent analog [Nle4, D-Phe7]alpha -MSH (NDP-MSH), labeled or not with the paramagnetic amino acid probe 2,2,6,6-tetramthylpiperidine-N-oxyl-4-amino-4-carboxylic acid (Toac). Global analysis of fluorescence decay profiles measured in the pH range between 2.0 and 11.0 showed that, for each peptide, the data could be well fitted to three lifetimes whose values remained constant. The less populated short lifetime component changed little with pH and was ascribed to Trp g+ chi1 rotamer, in which electron transfer deactivation predominates over fluorescence. The long and intermediate lifetime preexponential factors interconverted along that pH interval and the result was interpreted as due to interconversion between Trp g- and trans chi1 rotamers, driven by conformational changes promoted by modifications in the ionization state of side-chain residues. The differences in the extent of interconversion in alpha-MSH and NDP-MSH are indicative of structural differences between the peptides, while titration curves suggest structural similarities between each peptide and its Toac-labeled species, in aqueous solution. Though less sensitive than fluorescence, the Toac electron spin resonance (ESR) isotropic hyperfine splitting parameter can also monitor the titration of side-chain residues located relatively far from the probe. Copyright (c) 2005 Wiley Periodicals, Inc.

Efficacy and safety of weight-based insulin glargine dose titration regimen compared with glucose level- and current dose-based regimens in hospitalized patients with type 2 diabetes: a randomized, controlled study.

Science.gov (United States)

Li, Xiaowei; Du, Tao; Li, Wangen; Zhang, Tong; Liu, Haiyan; Xiong, Yifeng

2014-09-01

Insulin glargine is widely used as basal insulin. However, published dose titration regimens for insulin glargine are complex. This study aimed to compare the efficacy and safety profile of a user-friendly, weight-based insulin glargine dose titration regimen with 2 published regimens. A total of 160 hospitalized patients with hyperglycemia in 3 medical centers were screened. Our inclusion criteria included age 18 to 80 years and being conscious. Exclusion criteria included pregnancy or breast-feeding and hepatic or renal dysfunction. A total of 149 patients were randomly assigned to receive weight-based, glucose level-based, or dose-based insulin glargine dose titration regimen between January 2011 and February 2013. The initial dose of insulin glargine was 0.2 U/kg. In the weight-based regimen (n = 49), the dose was titrated by increments of 0.1 U/kg daily. In the glucose level-based regimen (n = 51), the dose was titrated by 2, 4, 6, or 8 U daily when fasting blood glucose (FBG) was, respectively, between 7.0 and 7.9, 8.0 and 8.9, 9.0 and 9.9, or ≥10 mmol/L. In the current dose-based regimen (n = 49), titration was by daily increments of 20% of the current dose. The target FBG in all groups was ≤7.0 mmol/L. The incidence of hypoglycemia was recorded. One-way ANOVA and χ(2) test were used to compare data between the 3 groups. All but 1 patient who required additional oral antidiabetic medication completed the study. The mean (SD) time to achieve target FBG was 3.2 (1.2) days with the weight-based regimen and 3.7 (1.5) days with the glucose level-based regimen (P = 0.266). These times were both shorter than that achieved with the current dose-based regimen (4.8 [2.8] days; P = 0.0001 and P = 0.005, respectively). The daily doses of insulin glargine at the study end point were 0.43 (0.13) U/kg with the weight-based regimen, 0.50 (0.20) U/kg with the glucose level-based regimen, and 0.47 (0.23) U/kg with the current dose-based regimen (P = 0.184). The incidence

Does a patient-managed insulin intensification strategy with insulin glargine and insulin glulisine provide similar glycemic control as a physician-managed strategy? Results of the START (Self-Titration With Apidra to Reach Target) Study: a randomized noninferiority trial.

Science.gov (United States)

Harris, Stewart B; Yale, Jean-François; Berard, Lori; Stewart, John; Abbaszadeh, Babak; Webster-Bogaert, Susan; Gerstein, Hertzel C

2014-01-01

OBJECTIVE Diabetes self-management is universally regarded as a foundation of diabetes care. We determined whether comparable glycemic control could be achieved by self-titration versus physician titration of a once-daily bolus insulin dose in patients with type 2 diabetes who are unable to achieve optimal glycemia control with a basal insulin. RESEARCH DESIGN AND METHODS Patients with type 2 diabetes, an HbA1c level >7% (53 mmol/mol), and either nocturnal hypoglycemia episodes or an insufficient basal insulin glargine level (with or without oral agents) to achieve a fasting plasma glucose level ≤6 mmol/L (108 mg/dL) were studied. Participants all had bolus insulin glulisine added at breakfast and were allocated to either algorithm-guided patient self-titration or physician titration. The primary outcome was an HbA1c level ≤7% (53 mmol/mol) without severe hypoglycemia. RESULTS After a mean (SD) follow-up of 159.4 days (36.2 days), 28.4% of participants in the self-titration arm vs. 21.2% in the physician titration arm achieved an HbA1c level of ≤7% (53 mmol/mol) without severe hypoglycemia (between-group absolute difference 7.2%; 95% CI -3.2 to 17.7). The lower end of this 95% confidence interval was within the predetermined noninferiority boundary of -5% (P noninferiority = 0.011). CONCLUSIONS In stable patients with type 2 diabetes who are receiving doses of basal insulin glargine who require bolus insulin, a simple bolus insulin patient-managed titration algorithm is as effective as a physician-managed algorithm.

Global Manufacturing Research: Experience Exchange Group (EEG) contributions

DEFF Research Database (Denmark)

Bruun, Peter

1998-01-01

of preliminary studies found interesting to set upan EEG composed of representatives from industry and a researcher. Inthe paper some general research methods pertinent to the areaindustrial management is discussed. The EEG concept is introduced andcharacterised in comparison with the other methods. EEG...... activities aredescribed and a tentative coupling to the phases in a research processis proposed. Following this is a discussion of methodological andquality requirements. It is considered how EEG activities couldpossible contribute to an industrial rooted research. The paper endsup looking at future research......The intention of this paper is to clarify if and how an ExperienceExchange Group (EEG) can be involved in a research process in the areaof industrial management. For exemplification of the topic an ongoingresearch in global manufacturing is referred to. In this research itwas after a series...

Development of self and peer performance assessment on iodometric titration experiment

Science.gov (United States)

Nahadi; Siswaningsih, W.; Kusumaningtyas, H.

2018-05-01

This study aims to describe the process in developing of reliable and valid assessment to measure students’ performance on iodometric titration and the effect of the self and peer assessment on students’ performance. The self and peer-instrument provides valuable feedback for the student performance improvement. The developed assessment contains rubric and task for facilitating self and peer assessment. The participants are 24 students at the second-grade student in certain vocational high school in Bandung. The participants divided into two groups. The first 12 students involved in the validity test of the developed assessment, while the remain 12 students participated for the reliability test. The content validity was evaluated based on the judgment experts. Test result of content validity based on judgment expert show that the developed performance assessment instrument categorized as valid on each task with the realibity classified as very good. Analysis of the impact of the self and peer assessment implementation showed that the peer instrument supported the self assessment.

Rapid determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration

Institute of Scientific and Technical Information of China (English)

XIAO Jun-ping; WANG Xue-feng; ZHOU Qing-xiang; FAN Xiao-yuan; SU Xian-fa; Bai Hua-hua; DUAN Hai-jing

2007-01-01

A rapid, simple and sensitive method was demonstrated for the determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration. With the presence of sulfuric acid, phenol could be transferred into a nitroso-compound by reacting with NaNO2. The titration end-point was obtained by the formation of a sharp cut in the oscillopolarographic with infinitesimal NaNO2 on double platinum electrodes. The results showed that phenol had an excellent linear relationship over the range of 4.82×10-6 -9.65×10-3 mol/L, the RSD of the proposed method was lower than 1.5%, and the spiked recoveries of three real water samples were in the range of 95.6%-106.9%.

Determination of titanium and vanadium in aqueous solutions by potentiometric titration

International Nuclear Information System (INIS)

Sibirkin, A.A.; Elliev, Yu.E.

1996-01-01

Possibility of titanium and vanadium determination at their combined presence by bichromatometric chromometric titration with potentiometric indication of end point is shown. The technique is developed which allows to determine titanium and vanadium with relative standard derivation ±2% in amounts not less than 50 and 100 mg respectively

Small-volume potentiometric titrations: EPR investigations of Fe-S cluster N2 in mitochondrial complex I.

Science.gov (United States)

Wright, John J; Salvadori, Enrico; Bridges, Hannah R; Hirst, Judy; Roessler, Maxie M

2016-09-01

EPR-based potentiometric titrations are a well-established method for determining the reduction potentials of cofactors in large and complex proteins with at least one EPR-active state. However, such titrations require large amounts of protein. Here, we report a new method that requires an order of magnitude less protein than previously described methods, and that provides EPR samples suitable for measurements at both X- and Q-band microwave frequencies. We demonstrate our method by determining the reduction potential of the terminal [4Fe-4S] cluster (N2) in the intramolecular electron-transfer relay in mammalian respiratory complex I. The value determined by our method, E m7 =-158mV, is precise, reproducible, and consistent with previously reported values. Our small-volume potentiometric titration method will facilitate detailed investigations of EPR-active centres in non-abundant and refractory proteins that can only be prepared in small quantities. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Group Ia afferents likely contribute to short-latency interlimb reflexes in the human biceps femoris muscle

DEFF Research Database (Denmark)

Stevenson, Andrew James Thomas; Kamavuako, Ernest Nlandu; Geertsen, Svend Sparre

2017-01-01

amplitudes (4 vs. 8°) at the same 150°/s velocity (p’s > 0.08). Conclusion: Because fast conducting group Ia muscle spindle afferents are sensitive to changes in muscle stretch velocity, while group II spindle afferents are sensitive to changes in amplitude (Grey et al., JPhysiol., 2001; Matthews, Trends...... Neurosci., 1991), group Ia velocity sensitive muscle spindle afferents likely contribute to the short-latency crossed spinal reflexes in the cBF muscle following iKnee joint rotations. This supports the findings for the short-latency crossed responses in the human soleus muscle (Stubbs & Mrachacz...... neurons in humans, with primary contributions from group Ia muscle spindle afferents....

Flow cytometry as an improved method for the titration of Chlamydiaceae and other intracellular bacteria.

Science.gov (United States)

Käser, T; Pasternak, J A; Hamonic, G; Rieder, M; Lai, K; Delgado-Ortega, M; Gerdts, V; Meurens, F

2016-05-01

Chlamydiaceae is a family of intracellular bacteria causing a range of diverse pathological outcomes. The most devastating human diseases are ocular infections with C. trachomatis leading to blindness and genital infections causing pelvic inflammatory disease with long-term sequelae including infertility and chronic pelvic pain. In order to enable the comparison of experiments between laboratories investigating host-chlamydia interactions, the infectious titer has to be determined. Titer determination of chlamydia is most commonly performed via microscopy of host cells infected with a serial dilution of chlamydia. However, other methods including fluorescent ELISpot (Fluorospot) and DNA Chip Scanning Technology have also been proposed to enumerate chlamydia-infected cells. For viruses, flow cytometry has been suggested as a superior alternative to standard titration methods. In this study we compared the use of flow cytometry with microscopy and Fluorospot for the titration of C. suis as a representative of other intracellular bacteria. Titer determination via Fluorospot was unreliable, while titration via microscopy led to a linear read-out range of 16 - 64 dilutions and moderate reproducibility with acceptable standard deviations within and between investigators. In contrast, flow cytometry had a vast linear read-out range of 1,024 dilutions and the lowest standard deviations given a basic training in these methods. In addition, flow cytometry was faster and material costs were lower compared to microscopy. Flow cytometry offers a fast, cheap, precise, and reproducible alternative for the titration of intracellular bacteria like C. suis. © 2016 International Society for Advancement of Cytometry. © 2016 International Society for Advancement of Cytometry.

Characterization of Native and Modified Starches by Potentiometric Titration

OpenAIRE

Soto, Diana; Urdaneta, Jose; Pernia, Kelly

2014-01-01

The use of potentiometric titration for the analysis and characterization of native and modified starches is highlighted. The polyelectrolytic behavior of oxidized starches (thermal and thermal-chemical oxidation), a graft copolymer of itaconic acid (IA) onto starch, and starch esters (mono- and diester itaconate) was compared with the behavior of native starch, the homopolymer, and the acid employed as a graft monomer and substituent. Starch esters showed higher percentages of acidity, follo...

Titration of uranium trace amounts in waters environment

International Nuclear Information System (INIS)

Larabi-Gruet, N.; Ithurbide, A.; Poulesquen, A.; Beaucaire, C.; Peulon, S.; Chausse, A.

2007-01-01

In the framework of studies concerning the uranium migration in soils and rocks, it seems necessary to quantify the uranium(VI) dissolved in solution. In the environmental conditions, the uranium(VI) is present at trace amounts. The most adapted method to this study and easy to carry out is the Adsorptive Stripping Voltammetry. By addition of a compound (ligand) with a reducing and strong complexing power, the uranium(VI) present in solution is reduced into a U(VI)-ligand complex. This specie is then oxidized and adsorbed on the mercury droplet where an electrolytic pre-concentration of the element to determine the quantity of is carried out. At last, a cathodic re-dissolution of the specie adsorbed in the U(IV)-ligand complex is carried out. The chosen analytical method is the differential impulsional voltammetry. With this method, it is possible to quantify low electro-active species quantities (sensitivity ∼25 ppt (10 -10 mol.L -1 ) for the uranium). This titration method in solution has been optimized, at first, in a non complexing medium. Then, the uranium in solution has been titrated in media whose composition has been progressively complexed (additions of CO 3 2- , SO 4 2- , Cl - ..) for being at last representative of the environmental interstitial waters. At last, this study has been carried out too by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) in order to compare the analysis sensitivity of these two detection methods. (O.M.)

Contributions of separate reactions to the acid-base buffering of soils in brook floodplains (Central Forest State Reserve)

Science.gov (United States)

Sokolova, T. A.; Tolpeshta, I. I.; Rusakova, E. S.

2016-04-01

The acid-base buffering of gleyic gray-humus soils developed in brook floodplains and undisturbed southern-taiga landscapes has been characterized by the continuous potentiometric titration of soil water suspensions. During the interaction with an acid, the major amount of protons (>80%) is consumed for the displacement of exchangeable bases and the dissolution of Ca oxalates. In the O and AY horizons, Mn compounds make the major contribution (2-15%) to the acid buffering. The buffer reactions with the participation of Al compounds make up from 0.5 to 1-2% of the total buffering capacity, and the protonation of the surface OH groups of kaolinite consumes 2-3% of the total buffering capacity. The deprotonation of OH groups on the surface of Fe hydroxides (9-43%), the deprotonation of OH groups on the surface of illite crystals (3-19%), and the dissolution of unidentified aluminosilicates (9-14%) are the most significant buffer reactions whose contributions have been quantified during the interaction with a base. The contribution of the deprotonation of OH groups on the surface of kaolinite particles is lower (1-5%) because of the small specific surface area of this mineral, and that of the dissolution of Fe compounds is insignificant. In the AY horizon, the acid and base buffering of soil in the rhizosphere is higher than beyond the rhizosphere because of the higher contents of organic matter and nonsilicate Fe and Al compounds.

Anhydrous formic acid and acetic anhydride as solvent or additive in nonaqueous titrations.

Science.gov (United States)

Buvári-Barcza, A; Tóth, I; Barcza, L

2005-09-01

The use and importance of formic acid and acetic anhydride (Ac2O) is increasing in nonaqueous acid-base titrations, but their interaction with the solutes is poorly understood. This paper attempts to clarify the effect of the solvents; NMR and spectrophotometric investigations were done to reveal the interactions between some bases and the mentioned solvents. Anhydrous formic acid is a typical protogenic solvent but both the relative permittivity and acidity are higher than those of acetic acid (mostly used in assays of bases). These differences originate from the different chemical structures: liquid acetic acid contains basically cyclic dimers while formic acid forms linear associates. Ac2O is obviously not an acidic but an aprotic (very slightly protophilic) solvent, which supposedly dissociates slightly into acetyl (CH3CO+) and acetate (AcO-) ions. In fact, some bases react with Ac2O forming an associate: the Ac+ group is bound to the delta- charged atom of the reactant while AcO- is associated with the delta+ group at appropriate distance.

Use of isothermal titration calorimetry to study the interaction of short-chain alcohols with lipid membranes

DEFF Research Database (Denmark)

Trandum, Christa; Westh-Andersen, Peter; Jørgensen, Kent

1999-01-01

of short-chain alcohols on Lipid bilayers. isothermal titration calorimetry (ITC) has been used to determine the energy involved in the association of the alcohols with lipid bilayers. Pure unilamellar DMPC liposomes and DMPC liposomes incorporated with different amounts of cholesterol, sphingomyelin...... dependent on the lipid bilayer composition. In the presence of high concentrations of cholesterol, the binding enthalpy of ethanol is decreased, whereas the presence of ceramides enhances the enthalpic response of the lipid bilayer to ethanol. Isothermal titration calorimetry offers a new methodology...

Study on the use of solid electrodes for potentiometric titrations in non-aqueous solvents-I

International Nuclear Information System (INIS)

Fatibello Filho, O.; Carvalho, W.M. de; Capelato, M.D.; Bulhoes, L.O.S.; Almeida Neves, E.F. de

1984-01-01

Fatty acids and ethanolamines were titrated potentiometrically with tetrabutylammnonium hydroxide in methyl isobutyl ketone-isopropyl alcohol and with perchloric acid in ethanol, respectively. A study of utilization of Sb, Sn, W, PbO 2 , Ti and 316L stainless steel oxides - Ag/AgBr/Bu 4 NBr (x M)/solvent electrode systems have been investigated in comparison with the glass - Ag/AgBr/Bu 4 NBr (x M)/solvent system. The best performance was obtained using W, Sb, PbO 2 and Ti electrodes have yielded a larger potential shift than glass electrode for acid-base titration. (C.L.B.) [pt

pH and Titratable Acidity of different Cough Syrups in Nigeria ...

African Journals Online (AJOL)

Background: Cough linctuses are liquid oral medicines widely used in children to treat cough and related conditions. Some of their constituents are acidic and dental erosive. Objectives: This in vitro study aimed to evaluate the endogenous pH and titratable acidity of Nigerian cough syrups and also determine their erosive ...

Flower extract as an improvised indicator in acid – base titration ...

African Journals Online (AJOL)

Different flowers were collected and the extracts were tested for indicator properties in acidic and basic solutions. The results showed different colour changes in alkaline and colourless in acid solutions. When used in acid-base titration, the end points colours and the average titre values obtained matched with that of ...

Effects of pH, titratable acidity and calcium concentration of non ...

African Journals Online (AJOL)

It has also been reported that experimental addition of calcium in beverages can reduce the progression of erosion. This study was carried out to investigate effects the of pH, titratable acidity and calcium concentration of non alcoholic carbonated beverages on enamel erosion of extracted human premolar teeth. Method: ...

Comparison of manual versus automatic continuous positive airway pressure titration and the development of a predictive equation for therapeutic continuous positive airway pressure in Chinese patients with obstructive sleep apnoea.

Science.gov (United States)

Luo, Jiaying; Xiao, Sichang; Qiu, Zhihui; Song, Ning; Luo, Yuanming

2013-04-01

Whether the therapeutic nasal continuous positive airway pressure (CPAP) derived from manual titration is the same as derived from automatic titration is controversial. The purpose of this study was to compare the therapeutic pressure derived from manual titration with automatic titration. Fifty-one patients with obstructive sleep apnoea (OSA) (mean apnoea/hypopnoea index (AHI) = 50.6 ± 18.6 events/h) who were newly diagnosed after an overnight full polysomnography and who were willing to accept CPAP as a long-term treatment were recruited for the study. Manual titration during full polysomnography monitoring and unattended automatic titration with an automatic CPAP device (REMstar Auto) were performed. A separate cohort study of one hundred patients with OSA (AHI = 54.3 ± 18.9 events/h) was also performed by observing the efficacy of CPAP derived from manual titration. The treatment pressure derived from automatic titration (9.8 ± 2.2 cmH(2)O) was significantly higher than that derived from manual titration (7.3 ± 1.5 cmH(2)O; P titration (54.3 ± 18.9 events/h before treatment and 3.3 ± 1.7 events/h after treatment; P titration pressure derived from REMstar Auto is usually higher than the pressure derived from manual titration. © 2013 The Authors. Respirology © 2013 Asian Pacific Society of Respirology.

Semi-automated potentiometric titration method for uranium characterization.

Science.gov (United States)

Cristiano, B F G; Delgado, J U; da Silva, J W S; de Barros, P D; de Araújo, R M S; Lopes, R T

2012-07-01

The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. Copyright © 2011 Elsevier Ltd. All rights reserved.

Food group contribution of essential elements of the Sao Paulo State market basket

International Nuclear Information System (INIS)

Avegliano, Roseane P.; Maihara, Vera A.; Silva, Fabio F. da

2009-01-01

To establish a Market Basket of Sao Paulo state seventy-one foods, with a mean consumption of more than 2 g day -1 per person, were grouped into 30 food categories. The food groups were: cereals, leguminous, leafy vegetables, fruity vegetables, tuberous vegetables, tropical fruits, other fruits, flours, pastas, breads, biscuits, prime grade beef, standard grade beef, pork meats, other meats, poultry, milk/cream, other dairy products, sugars, sweets, salts, sauces, oils, fats, alcoholic beverages, non-alcoholic beverages, coffee, ready-made dishes, saltwater and freshwater fishes. Information about individual food consumption was obtained from a recent national household food budget survey 'POF 2002-2003' conducted by the Brazilian Institute for Geography and Statistics from July 2002 to June 2003. Sampling and kitchen preparation of foods were carried out in restaurants of the University of Sao Paulo. Each food item was individually prepared table-ready. Foods of the same group were mixed, homogenized, pulverized and analyzed for the determination of Ca, Cr, Fe, K, Na and Zn concentrations by Instrumental Neutron Activation Analysis. Average daily intake of each element was calculated by multiplying the element concentration in the food by the corresponding weight of the ready-to-consume food group. The contribution of each food group to the total daily intake of elements by the ready-to-consume food groups of the Market Basket was evaluated. The food groups representing the highest contributions were salts: 79% Na; breads: 37% Fe and 46% Cr; cereals: 19% Zn and milk/cream: 58% Ca and 24% K. (author)

Automated oxygen titration and weaning with FreeO2 in patients with acute exacerbation of COPD: a pilot randomized trial

Directory of Open Access Journals (Sweden)

Lellouche F

2016-08-01

Full Text Available François Lellouche,1 Pierre-Alexandre Bouchard,1 Maude Roberge,1 Serge Simard,1,2 Erwan L’Her,1,3 François Maltais,1 Yves Lacasse1 1Research Centre, 2Biostatistics Department, Quebec Heart and Lung Institute, Laval University, 3Emergency Medicine, Hôtel-Dieu de Lévis, Laval University, Quebec City, QC, Canada Introduction: We developed a device (FreeO2 that automatically adjusts the oxygen flow rates based on patients’ needs, in order to limit hyperoxia and hypoxemia and to automatically wean them from oxygen. Objective: The aim of this study was to evaluate the feasibility of using FreeO2 in patients hospitalized in the respiratory ward for an acute exacerbation of COPD. Methods: We conducted a randomized controlled trial comparing FreeO2 vs manual oxygen titration in the respiratory ward of a university hospital. We measured the perception of appropriateness of oxygen titration and monitoring in both groups by nurses and attending physicians using a Likert scale. We evaluated the time in the target range of oxygen saturation (SpO2 as defined for each patient by the attending physician, the time with severe desaturation (SpO2 <85%, and the time with hyperoxia (SpO2 >5% above the target. We also recorded length of stay, intensive care unit admissions, and readmission rate. Fifty patients were randomized (25 patients in both groups; mean age: 72±8 years; mean forced expiratory volume in 1 second: 1.00±0.49 L; and mean initial O2 flow 2.0±1.0 L/min. Results: Nurses and attending physicians felt that oxygen titration and monitoring were equally appropriate with both O2 administration systems. The percentage of time within the SpO2 target was significantly higher with FreeO2, and the time with severe desaturation and hyperoxia was significantly reduced with FreeO2. Time from study inclusion to hospital discharge was 5.8±4.4 days with FreeO2 and 8.4±6.0 days with usual oxygen administration (P=0.051. Conclusion: FreeO2 was deemed as an

Accuracy and precision of protein-ligand interaction kinetics determined from chemical shift titrations

Energy Technology Data Exchange (ETDEWEB)

Markin, Craig J.; Spyracopoulos, Leo, E-mail: leo.spyracopoulos@ualberta.ca [University of Alberta, Department of Biochemistry (Canada)

2012-12-15

NMR-monitored chemical shift titrations for the study of weak protein-ligand interactions represent a rich source of information regarding thermodynamic parameters such as dissociation constants (K{sub D}) in the micro- to millimolar range, populations for the free and ligand-bound states, and the kinetics of interconversion between states, which are typically within the fast exchange regime on the NMR timescale. We recently developed two chemical shift titration methods wherein co-variation of the total protein and ligand concentrations gives increased precision for the K{sub D} value of a 1:1 protein-ligand interaction (Markin and Spyracopoulos in J Biomol NMR 53: 125-138, 2012). In this study, we demonstrate that classical line shape analysis applied to a single set of {sup 1}H-{sup 15}N 2D HSQC NMR spectra acquired using precise protein-ligand chemical shift titration methods we developed, produces accurate and precise kinetic parameters such as the off-rate (k{sub off}). For experimentally determined kinetics in the fast exchange regime on the NMR timescale, k{sub off} {approx} 3,000 s{sup -1} in this work, the accuracy of classical line shape analysis was determined to be better than 5 % by conducting quantum mechanical NMR simulations of the chemical shift titration methods with the magnetic resonance toolkit GAMMA. Using Monte Carlo simulations, the experimental precision for k{sub off} from line shape analysis of NMR spectra was determined to be 13 %, in agreement with the theoretical precision of 12 % from line shape analysis of the GAMMA simulations in the presence of noise and protein concentration errors. In addition, GAMMA simulations were employed to demonstrate that line shape analysis has the potential to provide reasonably accurate and precise k{sub off} values over a wide range, from 100 to 15,000 s{sup -1}. The validity of line shape analysis for k{sub off} values approaching intermediate exchange ({approx}100 s{sup -1}), may be facilitated by

Computer-aided polymer design using group contribution plus property models

DEFF Research Database (Denmark)

Satyanarayana, Kavitha Chelakara; Abildskov, Jens; Gani, Rafiqul

2009-01-01

. Polymer repeat unit property prediction models are required to calculate the properties of the generated repeat units. A systematic framework incorporating recently developed group contribution plus (GC(+)) models and an extended CAMD technique to include design of polymer repeat units is highlighted...... in this paper. The advantage of a GC(+) model in CAMD applications is that a very large number of polymer structures can be considered even though some of the group parameters may not be available. A number of case studies involving different polymer design problems have been solved through the developed......The preliminary step for polymer product design is to identify the basic repeat unit structure of the polymer that matches the target properties. Computer-aided molecular design (CAMD) approaches can be applied for generating the polymer repeat unit structures that match the required constraints...

Semi-automatic version of the potentiometric titration method for characterization of uranium compounds

International Nuclear Information System (INIS)

Cristiano, Bárbara F.G.; Delgado, José Ubiratan; Wanderley S da Silva, José; Barros, Pedro D. de; Araújo, Radier M.S. de; Dias, Fábio C.; Lopes, Ricardo T.

2012-01-01

The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques. - Highlights: ► A semi-automatic potentiometric titration method was developed for U charaterization. ► K 2 Cr 2 O 7 was the only certified reference material used. ► Values obtained for U 3 O 8 samples were consistent with certified. ► Uncertainty of 0.01% was useful for characterization and intercomparison program.

Estimation of Properties of Pure Organic Substances with Group and Pair Contributions

Directory of Open Access Journals (Sweden)

J.E.S. Ourique

1997-06-01

Full Text Available ABSTRACTbstract - This work presents a new predictive method for the estimation of properties of pure organic substances. Each compound is assigned a molecular graph or an adjacency matrix representing its chemical structure, from which properties are then obtained as a summation of all contributions associated with functional groups and chemically bonded pairs of groups. The proposed technique is applied to the estimation of critical temperature, critical pressure, critical volume and normal boiling point of 325 organic compounds from different chemical species. Accurate predictions based solely on chemical structure are obtained

Comparison of Titration ICP and XRF Spectrometry Methods in Determination of Cerium in Lens Polishing Powder

International Nuclear Information System (INIS)

Ninlaphruk, Sumalee; Pichestapong, Pipat; Mungpayabal, Harinate; Jiyavaranant, Thitima; Srisukho, Supapan; Chaisai, Prapassurn

2004-10-01

Three analytical methods in determination of cerium in cerium oxide separated from monazite ore for producing lens polishing powder were compared. These methods are titration ICP and XRF spectrometry techniques. The cerium oxide sample with estimated 45% cerium content needed to be digested and converted into solution before the analysis. The analytical results shown significantly no difference between each method. However, the titration method was found to be more convenient and suitable for quality control in the production of cerium oxide as it does not require standard cerium and the complicated analytical instruments

Non-damaging laser therapy of the macula: Titration algorithm and tissue response

Science.gov (United States)

Palanker, Daniel; Lavinsky, Daniel; Dalal, Roopa; Huie, Philip

2014-02-01

Retinal photocoagulation typically results in permanent scarring and scotomata, which limit its applicability to the macula, preclude treatments in the fovea, and restrict the retreatments. Non-damaging approaches to laser therapy have been tested in the past, but the lack of reliable titration and slow treatment paradigms limited their clinical use. We developed and tested a titration algorithm for sub-visible and non-damaging treatments of the retina with pulses sufficiently short to be used with pattern laser scanning. The algorithm based on Arrhenius model of tissue damage optimizes the power and duration for every energy level, relative to the threshold of lesion visibility established during titration (and defined as 100%). Experiments with pigmented rabbits established that lesions in the 50-75% energy range were invisible ophthalmoscopically, but detectable with Fluorescein Angiography and OCT, while at 30% energy there was only very minor damage to the RPE, which recovered within a few days. Patients with Diabetic Macular Edema (DME) and Central Serous Retinopathy (CSR) have been treated over the edematous areas at 30% energy, using 200μm spots with 0.25 diameter spacing. No signs of laser damage have been detected with any imaging modality. In CSR patients, subretinal fluid resolved within 45 days. In DME patients the edema decreased by approximately 150μm over 60 days. After 3-4 months some patients presented with recurrence of edema, and they responded well to retreatment with the same parameters, without any clinically visible damage. This pilot data indicates a possibility of effective and repeatable macular laser therapy below the tissue damage threshold.

An equilibrium model for ligand-modified micellar-enhanced ultrafiltration. Selective separation of metal ions using iminoacetic substituted polyamines and a theoretical model for the titration behavior of polyamines