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.

Microculture virus titration--a simple colourimetric assay for influenza virus titration.

Science.gov (United States)

Levi, R; Beeor-Tzahar, T; Arnon, R

1995-03-01

Influenza antigens can be detected by several well established methods. However, when it is important to determine the titre of infective virions, a bioassay should be employed. The standard and the most widely used tests for influenza infectivity are titration carried out in embryonated hen eggs, or the plaque assay employing tissue culture techniques. A simple colourimetric assay for influenza virus detection and titration is described. Samples of allantoic fluid or mice lung homogenates were used to infect MDCK cultures in microplate wells. After an incubation period, the tetrazolium (MTT) colourimetric assay was used to determine cell viability, and when compared to untreated culture control enabled the detection and titration of several influenza strains. When samples were assayed simultaneously in embryonated eggs and by the MCVT method, good correlation in determined titres was obtained. The availability of an additional method for influenza titration allows more flexibility in the choice of titration method according to the specific needs of the study. Furthermore, this method lends itself to full automatization. Similar procedures should also be applicable to titration of other cytopathic viruses.

Comparison of VFA titration procedures used for monitoring the biogas process

DEFF Research Database (Denmark)

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

2014-01-01

(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 40mL of four times diluted digested manure was gently stirred (200rpm). Results from samples with different VFA......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...

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)

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.

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.

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

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

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

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.

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.

Contributions to the theory of catalytic titrations-III Neutralization catalytic titrations.

Science.gov (United States)

Gaál, F F; Abramović, B F

1985-07-01

Neutralization catalytic titrations of weak monoprotic adds and bases with both volumetric and coulometric addition of the titrant (strong base/acid) have been simulated by taking into account the equilibrium concentration of the catalyst during the titration. The influence of several factors on the shape of the simulated catalytic titration curve has been investigated and is discussed.

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)

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 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.

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%.

Sensitivity of the acid-base properties of clays to the methods of preparation and measurement. 2. Evidence from continuous potentiometric titrations.

Science.gov (United States)

Duc, Myriam; Gaboriaud, Fabien; Thomas, Fabien

2005-09-01

The effects of experimental procedures on the acid-base consumption titration curves of montmorillonite suspension were studied using continuous potentiometric titration. For that purpose, the hysteresis amplitudes between the acid and base branches were found to be useful to systematically evaluate the impacts of storage conditions (wet or dried), the atmosphere in titration reactor, the solid-liquid ratio, the time interval between successive increments, and the ionic strength. In the case of storage conditions, the increase of the hysteresis was significantly higher for longer storage of clay in suspension and drying procedures compared to "fresh" clay suspension. The titration carried out under air demonstrated carbonate contamination that could only be cancelled by performing experiments under inert gas. Interestingly, the increase of the time intervals between successive increments of titrant strongly emphasized the amplitude of hysteresis, which could be correlated with the slow kinetic process specifically observed for acid addition in acid media. Thus, such kinetic behavior is probably associated with dissolution processes of clay particles. However, the resulting curves recorded at different ionic strengths under optimized conditions did not show the common intersection point required to define point of zero charge. Nevertheless, the ionic strength dependence of the point of zero net proton charge suggested that the point of zero charge of sodic montmorillonite could be estimated as lower than 5.

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.

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.

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

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...

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.

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

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

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.

Four points function fitted and first derivative procedure for determining the end points in potentiometric titration curves: statistical analysis and method comparison.

Science.gov (United States)

Kholeif, S A

2001-06-01

A new method that belongs to the differential category for determining the end points from potentiometric titration curves is presented. It uses a preprocess to find first derivative values by fitting four data points in and around the region of inflection to a non-linear function, and then locate the end point, usually as a maximum or minimum, using an inverse parabolic interpolation procedure that has an analytical solution. The behavior and accuracy of the sigmoid and cumulative non-linear functions used are investigated against three factors. A statistical evaluation of the new method using linear least-squares method validation and multifactor data analysis are covered. The new method is generally applied to symmetrical and unsymmetrical potentiometric titration curves, and the end point is calculated using numerical procedures only. It outperforms the "parent" regular differential method in almost all factors levels and gives accurate results comparable to the true or estimated true end points. Calculated end points from selected experimental titration curves compatible with the equivalence point category of methods, such as Gran or Fortuin, are also compared with the new method.

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.

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)

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

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...

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.

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...

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…

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.

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.

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

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.

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.

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.)

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.

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.

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)

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.

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 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.

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

Directory of Open Access Journals (Sweden)

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.

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.

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%.

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

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 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

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.

The coulometric titration of acids and bases in m-cresol medium

NARCIS (Netherlands)

Bos, M.; Dahmen, E.A.M.F.

1974-01-01

A method is described for the coulometric titration of acids and bases in the solvent m-cresol. The method is suitable for bases with pKa values greater than 11 in m-cresol, or for acids with pKa values below 13 in m-cresol. Amounts of 5–50 μeq of acid or base can be determined with a relative

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 ...

Detoxification with titration and tapering in gamma-hydroxybutyrate (GHB) dependent patients : The Dutch GHB monitor project

NARCIS (Netherlands)

Dijkstra, Boukje A G; Kamal, Rama; van Noorden, Martijn S; de Haan, Hein; Loonen, Anton J.M.; De Jong, Cor A J

2016-01-01

BACKGROUND AND AIMS: Gamma-hydroxybutyrate (GHB) detoxification procedures have been insufficiently studied for effectiveness and safety. Based on case reports, benzodiazepines are generally regarded as first-choice agents in GHB detoxification. Detoxification by titration and tapering (DeTiTap)

Effect of temperature on the acid-base properties of the alumina surface: microcalorimetry and acid-base titration experiments.

Science.gov (United States)

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

2006-06-15

Sorption reactions on natural or synthetic materials that can attenuate the migration of pollutants in the geosphere could be affected by temperature variations. Nevertheless, most of the theoretical models describing sorption reactions are at 25 degrees C. To check these models at different temperatures, experimental data such as the enthalpies of sorption are thus required. Highly sensitive microcalorimeters can now be used to determine the heat effects accompanying the sorption of radionuclides on oxide-water interfaces, but enthalpies of sorption cannot be extracted from microcalorimetric data without a clear knowledge of the thermodynamics of protonation and deprotonation of the oxide surface. However, the values reported in the literature show large discrepancies and one must conclude that, amazingly, this fundamental problem of proton binding is not yet resolved. We have thus undertaken to measure by titration microcalorimetry the heat effects accompanying proton exchange at the alumina-water interface at 25 degrees C. Based on (i) the surface sites speciation provided by a surface complexation model (built from acid-base titrations at 25 degrees C) and (ii) results of the microcalorimetric experiments, calculations have been made to extract the enthalpic variations associated respectively to first and second deprotonation of the alumina surface. Values obtained are deltaH1 = 80+/-10 kJ mol(-1) and deltaH2 = 5+/-3 kJ mol(-1). In a second step, these enthalpy values were used to calculate the alumina surface acidity constants at 50 degrees C via the van't Hoff equation. Then a theoretical titration curve at 50 degrees C was calculated and compared to the experimental alumina surface titration curve. Good agreement between the predicted acid-base titration curve and the experimental one was observed.

Nap-titration : An effective alternative for continuous positive airway pressure titration

NARCIS (Netherlands)

Hoekema, A; Stegenga, B; Meinesz, AF; van der Hoeven, JH; Wijkstra, PJ

When treating Obstructive Steep Apnea-Hypopnea Syndrome (OSAHS) several alternatives for standard (manual) continuous positive airway pressure (CPAP) titration are feasible. A practical alternative is titration without polysomnography during an afternoon nap (Nap-titration). The aim of the present

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.

Thermometric titration of sulphate.

Science.gov (United States)

Williams, M B; Janata, J

1970-06-01

Direct thermometric titration of sulphate with a solution of barium perchlorate is proposed. The stoichiometry of the titration is shown to be critically dependent on the concentration of ethanol in the titration medium. The titration is rapid and suffers from only a few interferences.

Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

Directory of Open Access Journals (Sweden)

Musa Ahmad

2017-11-01

Full Text Available An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to any pH changes and could be used to determine the end-point of the acid-base titration.

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

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)

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 ...

Repeated dose titration versus age-based method in electroconvulsive therapy: a pilot study

NARCIS (Netherlands)

Aten, J.J.; Oudega, M.L.; van Exel, E.; Stek, M.L.; van Waarde, J.A.

2015-01-01

In electroconvulsive therapy (ECT), a dose titration method (DTM) was suggested to be more individualized and therefore more accurate than formula-based dosing methods. A repeated DTM (every sixth session and dose adjustment accordingly) was compared to an age-based method (ABM) regarding treatment

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.

Assembling and Using an LED-Based Detector to Monitor Absorbance Changes during Acid-Base Titrations

Science.gov (United States)

Santos, Willy G.; Cavalheiro, E´der T. G.

2015-01-01

A simple photometric assembly based in an LED as a light source and a photodiode as a detector is proposed in order to follow the absorbance changes as a function of the titrant volume added during the course of acid-base titrations in the presence of a suitable visual indicator. The simplicity and low cost of the electronic device allow the…

Boehm Titration Revisited (Part I: Practical Aspects for Achieving a High Precision in Quantifying Oxygen-Containing Surface Groups on Carbon Materials

Directory of Open Access Journals (Sweden)

Jan Schönherr

2018-04-01

Full Text Available Practical aspects of the Boehm titration method are evaluated for obtaining reliable results in the quantification of oxygen-containing surface groups in a short time. Analytical criteria such as accuracy, repeatability, precision, and robustness are applied. Oxidized multi-walled carbon nanotubes (MWCNTs are used as the model substance. Different reaction bases (NaHCO3(aq, Na2CO3(aq, NaOH(aq are applied and treatment times are studied. We also show that smaller amounts of carbon material can be reliably analyzed by using an autotitrator combined with a pH electrode. We find that indirect titration with Na2CO3 results in the highest titration precision and accuracy despite the lower base strength compared with NaOH. Therefore, CO2 impurities do not have to be removed and only 7 min is necessary for one titration. The titration error with respect to the proposed method is 0.15% of the aliquot volume. The mixing method during the carbon treatment with bases (stirring, shaking, ultrasound treatment has no influence on the result as long as one allows a few hours for the reaction to complete. Finally, we provide a standard operating procedure for obtaining results with high precision during Boehm titration.

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.

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

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.

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

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.

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.

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.

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

Modelling of acid-base titration curves of mineral assemblages

Directory of Open Access Journals (Sweden)

Stamberg Karel

2016-01-01

Full Text Available The modelling of acid-base titration curves of mineral assemblages was studied with respect to basic parameters of their surface sites to be obtained. The known modelling approaches, component additivity (CA and generalized composite (GC, and three types of different assemblages (fucoidic sandstones, sedimentary rock-clay and bentonite-magnetite samples were used. In contrary to GC-approach, application of which was without difficulties, the problem of CA-one consisted in the credibility and accessibility of the parameters characterizing the individual mineralogical components.

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.

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

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.

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.

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.

A large-scale radiometric micro-quantitative complement fixation test for serum antibody titration

International Nuclear Information System (INIS)

Bengali, Z.H.; Levine, P.H.; Das, S.R.

1980-01-01

A micro-quantitative complement fixation (CF) procedure based on 51 Cr release is described. The method employs 50% hemolysis as end point and the alternation equation to calculate the amount of complement involved in the hemolytic reaction. Compared to the conventional CF tests, the radiometric procedure described here is very precise and consistently reproducible. Also, since only 3 4-fold dilutions of sera are used for the titration of antibodies over a wide range of concentrations, the test is very concise and is economical to perform. Its format is amenable to automation and computerization. This radioimetric CF procedure is thus most useful for large-scale immunological research and epidemiological surveilance studies. (Auth.)

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

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

OpenAIRE

André Fernando Oliveira; Alexandre Correa Lima; Astréa F. Souza Silva; Rodrigo de Maio Almeida

2010-01-01

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 o...

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 ...

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.

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)

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.

3-D Surface Visualization of pH Titration "Topos": Equivalence Point Cliffs, Dilution Ramps, and Buffer Plateaus

Science.gov (United States)

Smith, Garon C.; Hossain, Md Mainul; MacCarthy, Patrick

2014-01-01

3-D topographic surfaces ("topos") can be generated to visualize how pH behaves during titration and dilution procedures. The surfaces are constructed by plotting computed pH values above a composition grid with volume of base added in one direction and overall system dilution on the other. What emerge are surface features that…

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.

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)

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)

Charge characteristics of humic and fulvic acids: comparative analysis by colloid titration and potentiometric titration with continuous pK-distribution function model.

Science.gov (United States)

Bratskaya, S; Golikov, A; Lutsenko, T; Nesterova, O; Dudarchik, V

2008-09-01

Charge characteristics of humic and fulvic acids of a different origin (inshore soils, peat, marine sediments, and soil (lysimetric) waters) were evaluated by means of two alternative methods - colloid titration and potentiometric titration. In order to elucidate possible limitations of the colloid titration as an express method of analysis of low content of humic substances we monitored changes in acid-base properties and charge densities of humic substances with soil depth, fractionation, and origin. We have shown that both factors - strength of acidic groups and molecular weight distribution in humic and fulvic acids - can affect the reliability of colloid titration. Due to deviations from 1:1 stoichiometry in interactions of humic substances with polymeric cationic titrant, the colloid titration can underestimate total acidity (charge density) of humic substances with domination of weak acidic functional groups (pK>6) and high content of the fractions with molecular weight below 1kDa.

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.

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)

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.

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.

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.

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

Indirect iodometric procedure for quantitation of Sn(II) in radiopharmaceutical kits

International Nuclear Information System (INIS)

Muddukrishna, S.N.; Chen, A.; Sykes, T.R.; Noujaim, A.A.; Alberta Univ., Edmonton, AB

1994-01-01

A method of quantitating stannous ion [Sn(II)] suitable for radiopharmaceutical kits, based on indirect iodometric titration, is described. The method is based on the oxidation of Sn(II) using a known excess of iodine and the excess unreacted iodine determined using thiosulphate by potentiometric titration. The titration cell is a beaker and the titrations are done conveniently under air using an autotitrator in approx. 4 min. The method is accurate and is linear in the range of approx. 10 μg to approx. 6 mg of Sn(II). Several radiopharmaceutical kits were analysed for their Sn(II) content using the method including those containing antibodies or other proteins. The studies indicate that the procedure is rapid, simple and accurate for routine quantitative estimation of Sn(II) in radiopharmaceutical preparations during development, manufacture and storage. (Author)

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

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.

Ultrasonic and densimetric titration applied for acid-base reactions.

Science.gov (United States)

Burakowski, Andrzej; Gliński, Jacek

2014-01-01

Classical acoustic acid-base titration was monitored using sound speed and density measurements. Plots of these parameters, as well as of the adiabatic compressibility coefficient calculated from them, exhibit changes with the volume of added titrant. Compressibility changes can be explained and quantitatively predicted theoretically in terms of Pasynski theory of non-compressible hydrates combined with that of the additivity of the hydration numbers with the amount and type of ions and molecules present in solution. It also seems that this development could be applied in chemical engineering for monitoring the course of chemical processes, since the applied experimental methods can be carried out almost independently on the medium under test (harmful, aggressive, etc.).

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.)

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.

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)

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.)

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)

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

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.

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.

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

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

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)

Systemic Errors in Quantitative Polymerase Chain Reaction Titration of Self-Complementary Adeno-Associated Viral Vectors and Improved Alternative Methods

Science.gov (United States)

Fagone, Paolo; Wright, J. Fraser; Nathwani, Amit C.; Nienhuis, Arthur W.; Davidoff, Andrew M.

2012-01-01

Abstract Self-complementary AAV (scAAV) vector genomes contain a covalently closed hairpin derived from a mutated inverted terminal repeat that connects the two monomer single-stranded genomes into a head-to-head or tail-to-tail dimer. We found that during quantitative PCR (qPCR) this structure inhibits the amplification of proximal amplicons and causes the systemic underreporting of copy number by as much as 10-fold. We show that cleavage of scAAV vector genomes with restriction endonuclease to liberate amplicons from the covalently closed terminal hairpin restores quantitative amplification, and we implement this procedure in a simple, modified qPCR titration method for scAAV vectors. In addition, we developed and present an AAV genome titration procedure based on gel electrophoresis that requires minimal sample processing and has low interassay variability, and as such is well suited for the rigorous quality control demands of clinical vector production facilities. PMID:22428975

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

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)

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)

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.

Detoxification with titration and tapering in gamma-hydroxybutyrate (GHB) dependent patients: The Dutch GHB monitor project.

Science.gov (United States)

Dijkstra, Boukje A G; Kamal, Rama; van Noorden, Martijn S; de Haan, Hein; Loonen, Anton J M; De Jong, Cor A J

2017-01-01

Gamma-hydroxybutyrate (GHB) detoxification procedures have been insufficiently studied for effectiveness and safety. Based on case reports, benzodiazepines are generally regarded as first-choice agents in GHB detoxification. Detoxification by titration and tapering (DeTiTap) with pharmaceutical GHB in an open-label consecutive case series of 23 GHB-dependent patients showed to be feasible, effective and safe. This study further explored the feasibility, effectiveness and safety of this detoxification procedure in a large group of patients. A large observational multicenter study was carried out in six addiction treatment centers in the Netherlands. GHB-dependent inpatients (229 unique patients, 274 admissions) were titrated on and tapered off with pharmaceutical GHB. Successful detoxification was achieved in 85% of cases. Detoxification was carried out in 12.5days in most patients. The DeTiTap procedure proved to be feasible and significantly reduced the experienced withdrawal symptoms and craving (p≤0.001). Several symptoms were found to influence the course of subjective withdrawal symptoms. During detoxification, psychological symptoms such as depression, anxiety, and stress decreased (p≤0.05). The main complications were hypertension and anxiety. Six patients were sent to the general hospital for observation, but all six were able to continue detoxification in the addiction treatment centers. Most patients (69%) relapsed within three months after detoxification. The DeTiTap procedure using pharmaceutical GHB seems a safe alternative to benzodiazepines as a GHB detoxification procedure. However, the high relapse rates warrant further investigation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

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.

[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.

Sequential injection redox or acid-base titration for determination of ascorbic acid or acetic acid.

Science.gov (United States)

Lenghor, Narong; Jakmunee, Jaroon; Vilen, Michael; Sara, Rolf; Christian, Gary D; Grudpan, Kate

2002-12-06

Two sequential injection titration systems with spectrophotometric detection have been developed. The first system for determination of ascorbic acid was based on redox reaction between ascorbic acid and permanganate in an acidic medium and lead to a decrease in color intensity of permanganate, monitored at 525 nm. A linear dependence of peak area obtained with ascorbic acid concentration up to 1200 mg l(-1) was achieved. The relative standard deviation for 11 replicate determinations of 400 mg l(-1) ascorbic acid was 2.9%. The second system, for acetic acid determination, was based on acid-base titration of acetic acid with sodium hydroxide using phenolphthalein as an indicator. The decrease in color intensity of the indicator was proportional to the acid content. A linear calibration graph in the range of 2-8% w v(-1) of acetic acid with a relative standard deviation of 4.8% (5.0% w v(-1) acetic acid, n=11) was obtained. Sample throughputs of 60 h(-1) were achieved for both systems. The systems were successfully applied for the assays of ascorbic acid in vitamin C tablets and acetic acid content in vinegars, respectively.

Concentration-related response potentiometric titrations to study the interaction of small molecules with large biomolecules.

Science.gov (United States)

Hamidi-Asl, Ezat; Daems, Devin; De Wael, Karolien; Van Camp, Guy; Nagels, Luc J

2014-12-16

In the present paper, the utility of a special potentiometric titration approach for recognition and calculation of biomolecule/small-molecule interactions is reported. This approach is fast, sensitive, reproducible, and inexpensive in comparison to the other methods for the determination of the association constant values (Ka) and the interaction energies (ΔG). The potentiometric titration measurement is based on the use of a classical polymeric membrane indicator electrode in a solution of the small-molecule ligand. The biomolecule is used as a titrant. The potential is measured versus a reference electrode and transformed into a concentration-related signal over the entire concentration interval, also at low concentrations, where the millivolt (y-axis) versus log canalyte (x-axis) potentiometric calibration curve is not linear. In the procedure, Ka is calculated for the interaction of cocaine with a cocaine binding aptamer and with an anticocaine antibody. To study the selectivity and cross-reactivity, other oligonucleotides and aptamers are tested, as well as other small ligand molecules such as tetrakis(4-chlorophenyl)borate, metergoline, lidocaine, and bromhexine. The calculated Ka compared favorably to the value reported in the literature using surface plasmon resonance. The potentiometric titration approach called "concentration-related response potentiometry" is used to study molecular interaction for seven macromolecular target molecules and four small-molecule ligands.

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...

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

Development of a Novel Solid-State Sensor Electrode Based on Titanium Thin Film as an Indicator Electrode in Potentiometric and Conductometric Acid-Base Titration in Aqueous Solution

OpenAIRE

Abu Ghalwa, Nasser

2012-01-01

A modified Ti/(SnO2 + Sb2O3) electrode was prepared by thermal deposition on titanium substrate and its use as indicator electrode to potentiometric and conductometric acid-base titration in aqueous solution at 298 K was developed. The E-pH curve is linear with slope of 0.0512 V/dec at 298 K. The standard potential of this electrode, E0, was determined with respect to the SCE as reference electrode. The recovery percentages for potentiometric and conductometric acid-base titration for acetic ...

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.

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.

Chemical processes at the surface of various clays on acid-base titration

International Nuclear Information System (INIS)

Park, K. K.; Park, Y. S.; Jung, E. C.

2010-01-01

The chemical reaction of radionuclides at the interface between groundwater and geological mineral is an important process determining their retardation of transport through groundwater flow in a nuclear waste disposal. Clay minerals are major components of soil and argillaceous rock, and some of them are considered to be important base materials in the design of high-level nuclear waste repository due to their large swelling, low-permeability, large surface area, and strong and large sorption of radionuclides. Clay materials are phyllosilicates containing accessory minerals such as metal oxides, hydroxides, oxyhydroxides. Their structures are condensed 1:1 or 2:1 layers of tetrahedral SiO 3/2 OH and octahedral Al(OH) 6/2 sheets. An accurate knowledge about the properties of clay surface is required as a parameter for a long-term estimation of radionuclide retardation effects. Electric surface charge is a primary property determining ion exchange and surface complexation of radionuclides on its surface. The sources of electric surface charge are a permanent structural negative charge on a basal plane and a dissociable charge at an edge surface. Investigation of proton sorption is a prerequisite to the understanding of radionuclide sorption. The reactions on a permanently charged site and on an edge site are measured by an electrokinetic measurement and by potentiometric titration, respectively. However, side reactions such as complexation, proton/cation exchange, dissolution, hydrolysis, precipitation and re adsorption, and the reaction of secondary minerals hinder an experimental measurement of accurate acid-base properties. This presentation describes the pH change on dispersing various clays in water and adding acid, base or Eu(III) ion to these solutions, and the effect of Eu(III) ion on acid-base titration of clay solutions

Chemical processes at the surface of various clays on acid-base titration

Energy Technology Data Exchange (ETDEWEB)

Park, K. K.; Park, Y. S.; Jung, E. C. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-10-15

The chemical reaction of radionuclides at the interface between groundwater and geological mineral is an important process determining their retardation of transport through groundwater flow in a nuclear waste disposal. Clay minerals are major components of soil and argillaceous rock, and some of them are considered to be important base materials in the design of high-level nuclear waste repository due to their large swelling, low-permeability, large surface area, and strong and large sorption of radionuclides. Clay materials are phyllosilicates containing accessory minerals such as metal oxides, hydroxides, oxyhydroxides. Their structures are condensed 1:1 or 2:1 layers of tetrahedral SiO{sub 3/2}OH and octahedral Al(OH){sub 6/2} sheets. An accurate knowledge about the properties of clay surface is required as a parameter for a long-term estimation of radionuclide retardation effects. Electric surface charge is a primary property determining ion exchange and surface complexation of radionuclides on its surface. The sources of electric surface charge are a permanent structural negative charge on a basal plane and a dissociable charge at an edge surface. Investigation of proton sorption is a prerequisite to the understanding of radionuclide sorption. The reactions on a permanently charged site and on an edge site are measured by an electrokinetic measurement and by potentiometric titration, respectively. However, side reactions such as complexation, proton/cation exchange, dissolution, hydrolysis, precipitation and re adsorption, and the reaction of secondary minerals hinder an experimental measurement of accurate acid-base properties. This presentation describes the pH change on dispersing various clays in water and adding acid, base or Eu(III) ion to these solutions, and the effect of Eu(III) ion on acid-base titration of clay solutions

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)

Determination of surface charge density of α-alumina by acid-base titration

Directory of Open Access Journals (Sweden)

Justin W. Ntalikwa

2007-04-01

Full Text Available The surface charge density (σo of colloidal alpha alumina suspended in various 1:1 electrolytes was measured using acid-base titration. An autotitrator capable of dispensing accurately 25 plus or minus 0.1 μL of titrant was used. The pH and temperature in the titration cell were monitored using single junction electrodes and platinum resistance thermometers, respectively. A constant supply of nitrogen gas in the cell was used to maintain inert conditions. The whole set up was interfaced with a computer for easy data acquisition. It was observed that the material exhibits a point of zero charge (PZC, this occurred at pH of 7.8 plus or minus 0.1, 7.6 plus or minus 0.2, 8.5 plus or minus 0.1, 8.3 plus or minus 0.1 for NaCl, NaNO3, CsCl and CsNO3 systems, respectively. It was also observed that below PZC, σo increases with increase in electrolyte concentration (Co whereas above PZC, σo decreases with increase in Co. It was concluded that σo of this material is a function of pH and Co and that its polarity can be varied through zero by varying these parameters.

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...

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.

Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

OpenAIRE

Musa Ahmad; T.W. Tan

2017-01-01

An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to ...

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

ASSESSMENT OF ATTENTION THRESHOLD IN RATS BY TITRATION OF VISUAL CUE DURATION DURING THE FIVE CHOICE SERIAL REACTION TIME TASK

Science.gov (United States)

Martin, Thomas J.; Grigg, Amanda; Kim, Susy A.; Ririe, Douglas G.; Eisenach, James C.

2014-01-01

Background The 5 choice serial reaction time task (5CSRTT) is commonly used to assess attention in rodents. We sought to develop a variant of the 5CSRTT that would speed training to objective success criteria, and to test whether this variant could determine attention capability in each subject. New Method Fisher 344 rats were trained to perform a variant of the 5CSRTT in which the duration of visual cue presentation (cue duration) was titrated between trials based upon performance. The cue duration was decreased when the subject made a correct response, or increased with incorrect responses or omissions. Additionally, test day challenges were provided consisting of lengthening the intertrial interval and inclusion of a visual distracting stimulus. Results Rats readily titrated the cue duration to less than 1 sec in 25 training sessions or less (mean ± SEM, 22.9 ± 0.7), and the median cue duration (MCD) was calculated as a measure of attention threshold. Increasing the intertrial interval increased premature responses, decreased the number of trials completed, and increased the MCD. Decreasing the intertrial interval and time allotted for consuming the food reward demonstrated that a minimum of 3.5 sec is required for rats to consume two food pellets and successfully attend to the next trial. Visual distraction in the form of a 3 Hz flashing light increased the MCD and both premature and time out responses. Comparison with existing method The titration variant of the 5CSRTT is a useful method that dynamically measures attention threshold across a wide range of subject performance, and significantly decreases the time required for training. Task challenges produce similar effects in the titration method as reported for the classical procedure. Conclusions The titration 5CSRTT method is an efficient training procedure for assessing attention and can be utilized to assess the limit in performance ability across subjects and various schedule manipulations. PMID

A new method for determining the acid number of biodiesel based on coulometric titration.

Science.gov (United States)

Barbieri Gonzaga, Fabiano; Pereira Sobral, Sidney

2012-08-15

A new method is proposed for determining the acid number (AN) of biodiesel using coulometric titration with potentiometric detection, basically employing a potentiostat/galvanostat and an electrochemical cell containing a platinum electrode, a silver electrode, and a combination pH electrode. The method involves a sequential application of a constant current between the platinum (cathode) and silver (anode) electrodes, followed by measuring the potential of the combination pH electrode, using an isopropanol/water mixture as solvent and LiCl as the supporting electrolyte. A preliminary evaluation of the new method, using acetic acid for doping a biodiesel sample, showed an average recovery of 100.1%. Compared to a volumetric titration-based method for determining the AN of several biodiesel samples (ranging from about 0.18 to 0.95 mg g(-1)), the new method produced statistically similar results with better repeatability. Compared to other works reported in the literature, the new method presented an average repeatability up to 3.2 times better and employed a sample size up to 20 times smaller. Copyright © 2012 Elsevier B.V. All rights reserved.

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.

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.

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...

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.

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 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…

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.

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

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.)

Stabilization of the initial electrochemical potential for a metal-based potentiometric titration study of a biosorption process.

Science.gov (United States)

Naja, Ghinwa; Mustin, Christian; Volesky, Bohumil; Berthelin, Jacques

2006-01-01

An interactive metal-based potentiometric titration method has been developed using an ion selective electrode for studying the sorption of metal cations. The accuracy of this technique was verified by analyzing the metal sorption mechanism for the biomass of Rhizopus arrhizus fungus and diatomite, two dissimilar materials (organic and mineral, strong sorbent and weak sorbent) of a different order of cation exchange capacity. The problem of the initial electrochemical potential was addressed identifying the usefulness of a Na-sulfonic resin as a strong chelating agent applied before the beginning of sorption titration experiments so that the titration curves and the sorption uptake could be quantitatively compared. The resin stabilized the initial electrochemical potential to -405+/-5 mV corresponding to 2 micro gl(-1) of lead concentration in solution. The amounts of lead sorbed by R. arrhizus biomass and diatomite were 0.9 mmol g(-1) (C(e)=5.16 x 10(-2)mM) and 0.052 mmol g(-1) (C(e)=5.97 x 10(-2) mM), respectively. Lead sorption by the fungal biomass was pinpointed to at least two types of chemical active sites. The first type was distinguished by high reactivity and a low number of sites whereas the other was characterized by their higher number and lower reactivity.

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.

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...

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)

Automatic photometric titration of fluoride with thorium nitrate and alizarin S as indicator

International Nuclear Information System (INIS)

Bliefert, C.; Sobek, M.

1978-01-01

The photometric titration of fluoride with thorium nitrate and Alizarin S as indicator has been automated and optimized for fluoride levels between 1 and 20mg/85ml solution. The interference of several ions has been investigated. This procedure is particularly useful for the determination of fluoride after fusion with peroxides as fluxing agents. (orig.) [de

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.

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

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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.

Development of a Novel Solid-State Sensor Electrode Based on Titanium Thin Film as an Indicator Electrode in Potentiometric and Conductometric Acid-Base Titration in Aqueous Solution

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Nasser Abu Ghalwa

2012-01-01

Full Text Available A modified Ti/(SnO2 + Sb2O3 electrode was prepared by thermal deposition on titanium substrate and its use as indicator electrode to potentiometric and conductometric acid-base titration in aqueous solution at 298 K was developed. The E-pH curve is linear with slope of 0.0512 V/dec at 298 K. The standard potential of this electrode, E0, was determined with respect to the SCE as reference electrode. The recovery percentages for potentiometric and conductometric acid-base titration for acetic acid against NaOH were calculated. The cell constant, specific conductance, and the molar conductance with dilution for some common electrolytes were measured.

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

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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

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

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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.

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

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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.

Coulometric Titration of Ethylenediaminetetraacetate (EDTA) with Spectrophotometric Endpoint Detection: An Experiment for the Instrumental Analysis Laboratory

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Williams, Kathryn R.; Young, Vaneica Y.; Killian, Benjamin J.

2011-01-01

Ethylenediaminetetraacetate (EDTA) is commonly used as an anticoagulant in blood-collection procedures. In this experiment for the instrumental analysis laboratory, students determine the quantity of EDTA in commercial collection tubes by coulometric titration with electrolytically generated Cu[superscript 2+]. The endpoint is detected…

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

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

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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.

Nitric acid titration in the presence of UO2(NO3)2, Th(NO3)4, U(NO3)4 or Zr(NO3)4

International Nuclear Information System (INIS)

Nakashima, T.; Lieser, K.H.

1986-01-01

Procedures are described for titration of HNO 3 in presence of UO 2 2+ , Th 4+ , U 4+ and Zr 4+ without formation of interfering precipitates. In the first step the hydrolysable ions are masked by addition of complexing agents and in the second step the acid is titrated by NaOH as usual. (orig.)

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

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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.

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

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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.

Coulometric titrations of bases in propylene carbonate and g-butyrolactone using hydroquinone as the depolarizer and a quinhydrone indicator electrode

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Z. D. STANIC

2000-08-01

Full Text Available The application of hydroquinone for the coulometric generation of hydrogen ions in propylene carbonate (PC and g-butyrolactone (GBL is described. The current-potential curves recorded for theid sepolarizer, titrated bases, indicator and the solvents used showed that the investigated depolarizer is oxidized at lower potentials than the oxidation potentials of other components in the solution. the hydrogen ions generated by the oxidation of hydroquinone were used for the titration of organic bases (triethylamine, n-butylamine, pyridine, quinoline, aniline, N,N’-diphenylguanidine, piperidine, and 2,2’-bipiridine in PC and GBL with visual (Crystal Violet as indicator and potentiometric end-point detection using a quinhydrone electrode as the indicator electrode. The quinhydrone added to the to be analyzed solution served both as a source of hydrogen ions and, together with the immersed platinum electrode, as a quinhydrone electrode. The relative error of the determination of the bases was about 1 %.

Fluorescence-Based Comparative Binding Studies of the Supramolecular Host Properties of PAMAM Dendrimers Using Anilinonaphthalene Sulfonates: Unusual Host-Dependent Fluorescence Titration Behavior

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Natasa Stojanovic

2010-04-01

Full Text Available This work describes the fluorescence enhancement of the anilinonaphthalene sulfonate probes 1,8-ANS, 2,6-ANS, and 2,6-TNS via complexation with PAMAM dendrimer hosts of Generation 4, 5 and 6. The use of this set of three very closely related probes allows for comparative binding studies, with specific pairs of probes differing only in shape (1,8-ANS and 2,6-ANS, or in the presence of a methyl substituent (2,6-TNS vs. 2,6-ANS. The fluorescence of all three probes was significantly enhanced upon binding with PAMAM dendrimers, however in all cases except one, a very unusual spike was consistently observed in the host fluorescence titration plots (fluorescence enhancement vs. host concentration at low dendrimer concentration. This unprecedented fluorescence titration curve shape makes fitting the data to a simple model such as 1:1 or 2:1 host: guest complexation very difficult; thus only qualitative comparisons of the relative binding of the three guests could be made based on host titrations. In the case of G4 and G5 dendrimers, the order of binding strength was qualitatively determined to be 1,8-ANS < 2,6-ANS indicating that the more streamlined 2,6-substituted probes are a better match for the dendrimer cavity shape than the bulkier 1,8-substituted probe. This order of binding strength was also indicated by double fluorometric titration experiments, involving both host and guest titrations. Further double fluorometric titration experiments on 2,6-ANS in G4 dendrimer revealed a host concentration-dependent change in the nature of the host: guest complexation, with multiple guests complexed per host molecule at very low host concentrations, but less than one guest per host at higher concentrations.

Thermometric titration of acids in pyridine.

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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 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.

Titratable acidity of beverages influences salivary pH recovery.

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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.

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.

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

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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.

Validation of analytical procedure of quantitative determination of 5,7-bis(meta-nitrophenylamino-4,6-dinitrobenzofuroxan by potentiometric titration

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R. Sh. Markhabullina

2014-01-01

Full Text Available A new method of quantitative determination of the substance of 5,7-bis(meta-nitrophenylamino-4,6-dinitrobenzofuroxan using potentiometric titration method is developed. The method has high precision, reliability and sensitivity.

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.)

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.

The SimpleMix study with biphasic insulin aspart 30: a randomized controlled trial investigating patient-driven titration versus investigator-driven titration.

Science.gov (United States)

Gao, Yan; Luquez, Cecilia; Lynggaard, Helle; Andersen, Henning; Saboo, Banshi

2014-12-01

The study aimed to confirm the efficacy, through non-inferiority, of patient-driven versus investigator-driven titration of biphasic insulin aspart 30 (BIAsp 30) in terms of glycemic control assessed by HbA1c change. SimpleMix was a 20 week, open-label, randomized, two-armed, parallel-group, multicenter study in five countries (Argentina, China, India, Poland, and the UK). Patients with type 2 diabetes were randomized into either patient-driven or investigator-driven BIAsp 30 titration groups. Non-inferiority of patient-driven vs. investigator-driven titration based on change in HbA1c from baseline to week 20 could not be demonstrated. Mean (SE) estimated change from baseline to week 20 was -0.72 (0.08)% in the patient-driven group and -0.97 (0.08)% in the investigator-driven group; estimated difference 0.25% (95% CI: 0.04; 0.46). Estimated mean change (SE) in fasting plasma glucose from baseline to week 20 was similar between groups: -0.94 (0.21) mmol/L for patient-driven and -1.07 (0.22) mmol/L for investigator-driven (difference non-significant). Both treatment arms were well tolerated, and hypoglycemic episode rates were similar between groups, with a rate ratio of 0.77 (95% CI: 0.54; 1.09; p = 0.143) for all hypoglycemic episodes and 0.78 (95% CI: 0.42; 1.43; p = 0.417) for nocturnal hypoglycemic episodes. Non-inferiority of patient-driven versus investigator-driven titration with regard to change from baseline to end-of-treatment HbA1c could not be confirmed. It is possible that a clinic visit 12 weeks after intensification of treatment with BIAsp 30 in patients with type 2 diabetes inadequately treated with basal insulin may benefit patient-driven titration of BIAsp 30. A limitation of the study was the relatively small number of patients recruited in each country, which does not allow country-specific analyses to be performed. Overall, treatment with BIAsp 30 was well tolerated in both treatment groups.

Indirect potentiometric titration of ascorbic acid in pharmaceutical preparations using copper based mercury film electrode.

Science.gov (United States)

Abdul Kamal Nazer, Meeran Mohideen; Hameed, Abdul Rahman Shahul; Riyazuddin, Patel

2004-01-01

A simple and rapid potentiometric method for the estimation of ascorbic acid in pharmaceutical dosage forms has been developed. The method is based on treating ascorbic acid with iodine and titration of the iodide produced equivalent to ascorbic acid with silver nitrate using Copper Based Mercury Film Electrode (CBMFE) as an indicator electrode. Interference study was carried to check possible interference of usual excipients and other vitamins. The precision and accuracy of the method was assessed by the application of lack-of-fit test and other statistical methods. The results of the proposed method and British Pharmacopoeia method were compared using F and t-statistical tests of significance.

Titulações espectrofotométricas de sistemas ácido-base utilizando extrato de flores contendo antocianinas Spectrophotometric titrations of acid-base systems using flower extracts containig anthocyanins

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Mônica Souza Cortes

2007-08-01

Full Text Available Considering the attraction of the students' attention by the changes in the colors of vegetable crude extracts caused by the variation of the pH of the medium, the use of these different colors in order to demonstrate principles of spectrophotometric acid-base titrations using the crude extracts as indicators is proposed. The experimental setup consisted of a simple spectrophotometer, a homemade flow cell and a pump to propel the fluids along the system. Students should be stimulated to choose the best wavelength to monitor the changes in color during the titration. Since the pH of the equivalence point depends on the system titrated, the wavelength must be properly chosen to follow these changes, demonstrating the importance of the correct choice of the indicator. When compared with the potentiometric results, errors as low as 2% could be found using Rhododendron simsii (azalea or Tibouchina granulosa (Glory tree, quaresmeira as sources of the crude extracts.

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.

Simulation-Based Evaluation of Dose-Titration Algorithms for Rapid-Acting Insulin in Subjects with Type 2 Diabetes Mellitus Inadequately Controlled on Basal Insulin and Oral Antihyperglycemic Medications.

Science.gov (United States)

Ma, Xiaosu; Chien, Jenny Y; Johnson, Jennal; Malone, James; Sinha, Vikram

2017-08-01

The purpose of this prospective, model-based simulation approach was to evaluate the impact of various rapid-acting mealtime insulin dose-titration algorithms on glycemic control (hemoglobin A1c [HbA1c]). Seven stepwise, glucose-driven insulin dose-titration algorithms were evaluated with a model-based simulation approach by using insulin lispro. Pre-meal blood glucose readings were used to adjust insulin lispro doses. Two control dosing algorithms were included for comparison: no insulin lispro (basal insulin+metformin only) or insulin lispro with fixed doses without titration. Of the seven dosing algorithms assessed, daily adjustment of insulin lispro dose, when glucose targets were met at pre-breakfast, pre-lunch, and pre-dinner, sequentially, demonstrated greater HbA1c reduction at 24 weeks, compared with the other dosing algorithms. Hypoglycemic rates were comparable among the dosing algorithms except for higher rates with the insulin lispro fixed-dose scenario (no titration), as expected. The inferior HbA1c response for the "basal plus metformin only" arm supports the additional glycemic benefit with prandial insulin lispro. Our model-based simulations support a simplified dosing algorithm that does not include carbohydrate counting, but that includes glucose targets for daily dose adjustment to maintain glycemic control with a low risk of hypoglycemia.

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.

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

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.)

Implementation of a pharmacist-managed heart failure medication titration clinic.

Science.gov (United States)

Martinez, Amanda S; Saef, Jerold; Paszczuk, Anna; Bhatt-Chugani, Hetal

2013-06-15

The development, implementation, and initial results of a pharmacist-managed heart failure (HF) medication titration clinic are described. In a quality-improvement initiative at a Veterans Affairs health care system, clinical pharmacists were incorporated into the hospital system's interprofessional outpatient HF clinic. In addition, a separate pharmacist-managed HF medication titration clinic was established, in which pharmacists were granted an advanced scope of practice and prescribing privileges, enabling them to initiate and adjust medication dosages under specific protocols jointly established by cardiology and pharmacy staff. Pharmacists involved in the titration clinic tracked patients' daily body weight, vital signs, and volume status using telephone-monitoring technology and via patient interviews. A retrospective chart review comparing achievement of target doses of angiotensin-converting enzyme inhibitor (ACEI), angiotensin-receptor blocker (ARB), and β-blocker therapies in a group of patients (n = 28) whose dosage titrations were carried out by nurses or physicians prior to implementation of the pharmacist-managed HF medication titration clinic and a group of patients (n = 27) enrolled in the medication titration clinic during its first six months of operation indicated that target ACEI and ARB doses were achieved in a significantly higher percentage of pharmacist-managed titration clinic enrollees (52.9% versus 31%, p = 0.007). Patients enrolled in the pharmacist-managed HF medication titration clinic also had a significantly higher rate of attainment of optimal β-blocker doses (49% versus 24.7%, p = 0.012). Implementation of a pharmacist-managed HF medication titration clinic increased the percentage of patients achieving optimal ACEI, ARB, and β-blocker dosages.

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.

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.

Rapid clozapine titration in treatment-refractory bipolar disorder.

Science.gov (United States)

Ifteni, Petru; Correll, Christoph U; Nielsen, Jimmi; Burtea, Victoria; Kane, John M; Manu, Peter

2014-09-01

Clozapine is effective in treatment-refractory bipolar disorder (BD). Guidelines recommend slow titration to prevent seizures, hypotension and myocarditis, but this stance is not supported by comparative data. To evaluate the safety and effectiveness of rapid clozapine titration in BD. Analysis of a consecutive cohort of treatment-refractory BD patients with mixed/manic episode admitted on alternate days to one of two units of a psychiatric hospital. On one unit, clozapine was started at 25mg followed by 25-50mg as needed every 6h (maximum=100mg/day) on day 1, followed by increases of 25-100mg/day. On the other unit, clozapine was initiated with 25mg in day 1, followed by increases of 25-50mg/day. The primary outcome was the number of days from starting clozapine until readiness for discharge, adjusted in logistic regression for the number of antipsychotics tried during the hospitalization, psychotropic co-treatments and presence of psychotic features. Patients subject to rapid (N=44) and standard (N=23) titration were similar in age, gender, smoking status, body mass index, illness severity at baseline and discharge, and highest clozapine dose. Clozapine was discontinued due to hypotension (N=1) and pneumonia (N=1) during rapid titration, and for excessive sedation (N=1) in each titration group. The number of hospital days from starting clozapine until readiness for discharge was 3.8 days shorter in the rapid titration group (12.7±6.3 vs. 16.5±5.8, p=0.0077). Rapid clozapine titration appeared safe and effective for treatment-refractory BD. The potential for shorter hospital stays justifies prospective trials of this method. Copyright © 2014 Elsevier B.V. All rights reserved.

Determining surface areas of marine alga cells by acid-base titration method.

Science.gov (United States)

Wang, X; Ma, Y; Su, Y

1997-09-01

A new method for determining the surface area of living marine alga cells was described. The method uses acid-base titration to measure the surface acid/base amount on the surface of alga cells and uses the BET (Brunauer, Emmett, and Teller) equation to estimate the maximum surface acid/base amount, assuming that hydrous cell walls have carbohydrates or other structural compounds which can behave like surface Brönsted acid-base sites due to coordination of environmental H2O molecules. The method was applied to 18 diverse alga species (including 7 diatoms, 2 flagellates, 8 green algae and 1 red alga) maintained in seawater cultures. For the species examined, the surface areas of individual cells ranged from 2.8 x 10(-8) m2 for Nannochloropsis oculata to 690 x 10(-8) m2 for Dunaliella viridis, specific surface areas from 1,030 m2.g-1 for Dunaliella salina to 28,900 m2.g-1 for Pyramidomonas sp. Measurement accuracy was 15.2%. Preliminary studies show that the method may be more promising and accurate than light/electron microscopic measurements for coarse estimation of the surface area of living algae.

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

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.

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)

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…

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

Radiometric titration of diethanolamine with 65ZnSO4 and determination of mono and diethanolamines in a mixture by a radiometric method

International Nuclear Information System (INIS)

Varadan, R.; Sriman Narayanan, S.; Rao, V.R.S.

1984-01-01

Radiometric titration of diethanolamine with 65 ZnSO 4 is reported. Determination of individual amounts of mono- and diethanolamines in a mixture is described. The procedure is simple, rapid and accurate. (author)

Complexity in Acid–Base Titrations: Multimer Formation Between Phosphoric Acids and Imines

Science.gov (United States)

Malm, Christian; Kim, Heejae; Wagner, Manfred

2017-01-01

Abstract Solutions of Brønsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Brønsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid–base aggregates challenging. Here, we track such acid–base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by using a combination of dielectric relaxation and NMR spectroscopy. In contrast to what one would expect for an acid–base titration, we find strong deviations from quantitative proton transfer from the acid to the base. Even for an excess of the base, multimers consisting of one base and at least two acid molecules are formed, in addition to the occurrence of proton transfer from the acid to the base and simultaneous formation of ion pairs. For equimolar mixtures such multimers constitute about one third of all intermolecular aggregates. Quantitative analysis of our results shows that the acid‐base association constant is only around six times larger than that for the acid binding to an acid‐base dimer, that is, to an already protonated base. Our findings have implications for the interpretation of previous studies of reactive intermediates in organocatalysis and provide a rationale for previously observed nonlinear effects in phosphoric acid catalysis. PMID:28597513

Complexity in Acid-Base Titrations: Multimer Formation Between Phosphoric Acids and Imines.

Science.gov (United States)

Malm, Christian; Kim, Heejae; Wagner, Manfred; Hunger, Johannes

2017-08-10

Solutions of Brønsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Brønsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid-base aggregates challenging. Here, we track such acid-base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by using a combination of dielectric relaxation and NMR spectroscopy. In contrast to what one would expect for an acid-base titration, we find strong deviations from quantitative proton transfer from the acid to the base. Even for an excess of the base, multimers consisting of one base and at least two acid molecules are formed, in addition to the occurrence of proton transfer from the acid to the base and simultaneous formation of ion pairs. For equimolar mixtures such multimers constitute about one third of all intermolecular aggregates. Quantitative analysis of our results shows that the acid-base association constant is only around six times larger than that for the acid binding to an acid-base dimer, that is, to an already protonated base. Our findings have implications for the interpretation of previous studies of reactive intermediates in organocatalysis and provide a rationale for previously observed nonlinear effects in phosphoric acid catalysis. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

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.

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

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...

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.

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

''Titration'' polymerization of monovinylacetylene

NARCIS (Netherlands)

Mavinkurve, A; Visser, S; vandenBroek, W; Pennings, AJ

1996-01-01

A polymer consisting of a saturated carbon backbone with pendent acetylenic groups was prepared from monovinylacetylene. A titration was performed between the monomer and tertiary butyllithium, its lithiating agent. The charge transfer complex formed between the solvent THF and the tertiary

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.

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...

Standard test method for uranium by Iron (II) reduction in phosphoric acid followed by chromium (VI) titration in the presence of vanadium

CERN Document Server

American Society for Testing and Materials. Philadelphia

2011-01-01

1.1 This test method, commonly referred to as the Modified Davies and Gray technique, covers the titration of uranium in product, fuel, and scrap materials after the material is dissolved. The test method is versatile and has been ruggedness tested. With appropriate sample preparation, this test method can give precise and unbiased uranium assays over a wide variety of material types (1, 2). Details of the titration procedure in the presence of plutonium with appropriate modifications are given in Test Method C1204. 1.2 Uranium levels titrated are usually 20 to 50 mg, but up to 200 mg uranium can be titrated using the reagent volumes stated in this test method. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determ...

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.

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

Assessment of Knowledge of Self Blood Glucose Monitoring and Extent of Self Titration of Anti-Diabetic Drugs among Diabetes Mellitus Patients - A Cross Sectional, Community Based Study.

Science.gov (United States)

Krishnan, V; Thirunavukkarasu, J

2016-03-01

Self blood glucose monitoring is an important context of self care in the management of diabetes mellitus. All the guidelines must be followed while performing self blood glucose monitoring and tracking of values is essential to facilitate the physician while titrating the drugs and /or doses of anti diabetes medication. Self titration by patients following self monitoring must be discouraged. To assess the knowledge and practice of self blood glucose monitoring among diabetes patients and extent of self titration of anti diabetes medicines among diabetes patients based on self blood glucose monitoring. This pilot, cross-sectional, observational study was conducted using a validated questionnaire among adult male and female diabetes patients performing self blood glucose monitoring at home. Diabetes patients with complications and juvenile diabetes patients were excluded. Out of 153 patients surveyed, only 37 (24.1%) (20 males, 17 females) patients were aware and have been following self blood glucose monitoring appropriately. About 116 (75.8%) (64 males, 52 females) of patients were devoid of adequate knowledge and did not practice self blood glucose monitoring in a proper way. Ninety eight (64.05%) accepted that they self titrate their anti diabetic medicines based on self monitoring. Self monitoring of blood glucose should be encouraged and patients should be taught importance of following correct steps and tracking of self monitoring by physician or diabetes educator.

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.

Determination of pKa values of alendronate sodium in aqueous solution by piecewise linear regression based on acid-base potentiometric titration.

Science.gov (United States)

Ke, Jing; Dou, Hanfei; Zhang, Ximin; Uhagaze, Dushimabararezi Serge; Ding, Xiali; Dong, Yuming

2016-12-01

As a mono-sodium salt form of alendronic acid, alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups. The dissociation constants of alendronate sodium were determined in this work by studying the piecewise linear relationship between volume of titrant and pH value based on acid-base potentiometric titration reaction. The distribution curves of alendronate sodium were drawn according to the determined pKa values. There were 4 dissociation constants (pKa 1 =2.43, pKa 2 =7.55, pKa 3 =10.80, pKa 4 =11.99, respectively) of alendronate sodium, and 12 existing forms, of which 4 could be ignored, existing in different pH environments.

A potentiometric titration method for the crystallization of drug-like organic molecules.

Science.gov (United States)

Du-Cuny, Lei; Huwyler, Jörg; Fischer, Holger; Kansy, Manfred

2007-09-05

It is generally accepted, that crystalline solids representing a low energy polymorph should be selected for development of oral dosage forms. As a consequence, efficient and robust procedures are needed at an early stage during drug discovery to prepare crystals from drug-like organic molecules. In contrast to the use of supersaturated solutions, we present a potentiometric crystallization procedure where saturated solutions are prepared in a controlled manner by pH-titration. Crystallization is carried out under defined conditions using the sample concentration and experimental pK(a) values as input parameters. Crystals of high quality were obtained for 11 drugs selected to demonstrate the efficiency and applicability of the new method. Technical improvements are suggested to overcome practical limitations and to enhance the possibility of obtaining crystals from molecules in their uncharged form.

Radiometric titration of diethanolamine with /sup 65/ZnSO/sub 4/ and determination of mono and diethanolamines in a mixture by a radiometric method

Energy Technology Data Exchange (ETDEWEB)

Varadan, R.; Sriman Narayanan, S.; Rao, V.R.S. (Indian Inst. of Tech., Madras. Dept. of Chemistry)

1984-08-16

Radiometric titration of diethanolamine with /sup 65/ZnSO/sub 4/ is reported. Determination of individual amounts of mono- and diethanolamines in a mixture is described. The procedure is simple, rapid and accurate.

PC based controlled potential coulometric titrator for quantitative analysis of nuclear materials

International Nuclear Information System (INIS)

Manna, A.; Moorthy, A.D.; Bhogale, R.G.

2001-01-01

With increased requirements for process control and accountability of nuclear materials in plutonium reprocessing plants, the PC based controlled potential coulometric titrator was developed which has the capability of automatic quantitative analysis of the samples. The instruments based on electromechanical methods, incorporates an electronic potentiostat, a digital coulometer with wide dynamic range and a PC with a control interface card. The potentiostat is required to control the potential at the working electrode surface as per predetermined controlled voltage with respect to a reference electrode under wide variations in the conductivity and double layer capacitance of the electrochemical cell. The digital coulometer precisely measures the amount of electronic charge taking part in the electrochemical reactions of interest. The software has the facility to carry out three different types of analysis, i.e., primary coulometry, secondary coulometry and coulogram curve tracing. Due to complete analysis of the samples under program control, the human related errors are minimized and a better precision in the results are obtained. It has been possible to obtain an overall precession of better than +/- 0.3% in the determination of plutonium using the instrument. (author)

Antiepileptic Drug Titration and Related Health Care Resource Use and Costs.

Science.gov (United States)

Fishman, Jesse; Kalilani, Linda; Song, Yan; Swallow, Elyse; Wild, Imane

2018-02-27

Unexpected breakthrough seizures resulting from suboptimal antiepileptic drug (AED) dosing during the titration period, as well as adverse events resulting from rapid AED titration, may influence the titration schedule and significantly increase health care resource use (HRU) and health care costs. To assess the relationship between AEDs, HRU, and costs during AED titration and maintenance. Practicing neurologists were recruited from a nationwide panel to provide up to 3 patient records each for this retrospective medical chart review. Patients with epilepsy who were aged ≥ 18 years and had initiated an AED between January 1, 2014, and January 1, 2016, were followed for 6 months from AED initiation. Titration duration was the time from AED initiation to the beginning of treatment maintenance as determined by the physician. Outcomes were epilepsy-specific HRU (hospitalizations, emergency department visits, outpatient visits, physician referral, laboratory testing/diagnostic imaging, and phone calls) and related costs that occurred during the titration or maintenance treatment periods. Of 811 patients, 156, 128, 125, 120, 114, 107, and 61 initiated the following AEDs: levetiracetam, lamotrigine, lacosamide, valproate, topiramate, carbamazepine, and phenytoin, respectively. Most patients (619/803 [77.1%] with complete AED data) received monotherapy. Baseline characteristics were similar across AEDs (mean [SD] age, 36.6 [14.4] years; 59.0% male). Kaplan-Meier estimates of titration duration ranged from 3.3 weeks (phenytoin) to 8.1 weeks (lamotrigine). From titration to maintenance, the overall incidence of HRU per person-month decreased 54.5%-89.3% for each HRU measure except outpatient visits (24.6% decrease). Total epilepsy-related costs decreased from $80.48 to $42.77 per person-month, or 46.9% from titration to maintenance. AED titration periods had higher HRU rates and costs than AED maintenance, suggesting that use of AEDs with shorter titration requirements

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

The generalized lewis acid-base titration of palladium and niobium

Science.gov (United States)

Cima, M.; Brewer, L.

1988-12-01

The high thermodynamic stability of alloys composed of platinum group metals and group IVB and VB metals has been explained by an electronic interaction analogous to the Lewis acid-base concept for nontransition elements. The analogy is further demonstrated by the titration of palladium by addition of niobium. The activity of niobium in solid palladium was measured as a function of concentration by solid-state galvanic cells and study of the ternary oxide phase diagram. The galvanic cells were of the type Pt/NbO2,Nb2O4.8/YDTJNbOy,Nbpd/Pt where the solid electrolyte is yttria-doped thoria (YDT). Ternary phase diagrams for the Pd-Nb-0 and Rh-Nb-0 systems were obtained by characterizing samples equilibrated at 1000 °C. The phase relationships found in the ternary diagrams were also used to derive thermochemical data for the alloys. Thermochemical quantities for other acid-base stabilized alloys such as Nb-Rh, Ti-Pd, and Ti-Rh were also measured. The excess partial molar ΔGxs/R of niobium at infinite dilution was determined to be -31 kilo-Kelvin at 1000 °C, and the AG°JR of formation of a mole of NbPd3.55 is —21 kilo-Kelvin. These results and those for the other systems are used to assess the importance of valence electron configuration, nuclear charge, and crystal field effects in the context of generalized Lewis acid-base theory. It is concluded that both the nuclear charge of the atom and crystal field splitting of the valence orbitals significantly affect the basicity of the platinum group metals.

A one-step colorimetric acid-base titration sensor using a complementary color changing coordination system.

Science.gov (United States)

Cho, Hui Hun; Kim, Si Hyun; Heo, Jun Hyuk; Moon, Young Eel; Choi, Young Hun; Lim, Dong Cheol; Han, Kwon-Hoon; Lee, Jung Heon

2016-06-21

We report the development of a colorimetric sensor that allows for the quantitative measurement of the acid content via acid-base titration in a single-step. In order to create the sensor, we used a cobalt coordination system (Co-complex sensor) that changes from greenish blue colored Co(H2O)4(OH)2 to pink colored Co(H2O)6(2+) after neutralization. Greenish blue and pink are two complementary colors with a strong contrast. As a certain amount of acid is introduced to the Co-complex sensor, a portion of greenish blue colored Co(H2O)4(OH)2 changes to pink colored Co(H2O)6(2+), producing a different color. As the ratio of greenish blue and pink in the Co-complex sensor is determined by the amount of neutralization reaction occurring between Co(H2O)4(OH)2 and an acid, the sensor produced a spectrum of green, yellow green, brown, orange, and pink colors depending on the acid content. In contrast, the color change appeared only beyond the end point for normal acid-base titration. When we mixed this Co-complex sensor with different concentrations of citric acid, tartaric acid, and malic acid, three representative organic acids in fruits, we observed distinct color changes for each sample. This color change could also be observed in real fruit juice. When we treated the Co-complex sensor with real tangerine juice, it generated diverse colors depending on the concentration of citric acid in each sample. These results provide a new angle on simple but quantitative measurements of analytes for on-site usage in various applications, such as in food, farms, and the drug industry.

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.

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

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.)

Determinação de ferro (III em produtos farmacêuticos por titulação fotométrica = Determination of iron (III in pharmaceutical products by photometric titration

Directory of Open Access Journals (Sweden)

Airton Vicente Pereira

2011-01-01

Full Text Available Este trabalho descreve a montagem de um sistema de titulacao fotometrica simples e de baixo custo para a determinacao de ferro (III em produtos farmaceuticos. O sistema de titulacao fotometrica foi construido utilizando-se a bomba peristaltica de um espectrofotometro convencional. O procedimento e baseado na titulacao de ferro (III com EDTA e acido salicilico como indicador. A absorcao do complexo ferro (III-acido salicilico foi monitorada espectrofotometricamente em 525 nm. O limite de quantificacao foi de 5 ƒÝg de ferro (III. O procedimento de titulacao fotometrica foi aplicado para a determinacao de ferro (III em amostras contendo sulfato ferroso e hidroxido ferrico polimaltosado. O procedimento mostrou sensibilidade, reprodutibilidade e precisao para a utilizacao em analise rotineira de ferro (III em produtos farmaceuticos.This paper describes a simple, precise and low-cost photometrictitration method for iron (III determination in pharmaceutical preparations. The photometric titration system was constructed using the peristaltic pump of a conventional spectrophotometer. The method is based on titration of iron (III with EDTA using salicylic acid as indicator. The absorption of the iron (III-salicylic acid complex wasmonitored spectrophotometrically at 525 nm. The limit of quantification was 5 ƒÝg of iron (III. The photometric titration procedure was applied for the determination of iron (III in samples of ferrous sulfate and ferric hydroxide polymaltose complex. The procedure showed sensibility, reproducibility and accuracy for use as a method for the routine analysis of iron (III in pharmaceutical formulations.

Successive determinations of metals and boron in metal borides by chelatometric and alkalimetric titrations

International Nuclear Information System (INIS)

Takahashi, Yasuo; Higashi, Iwami; Atoda, Tetzuzo

1976-01-01

Based on the investigation of chemical reactivities of metal borides and of the metal chelate effects on the alkalimetric titration of boron, a method of successive determinations of metals and boron of Mn-, Fe-, Cu- and Al-borides has been developed. The procedure is as follows: (1) Mn-, Fe- and Cu-borides: Dissolve 10 to 30 mg of a sample in a mixture of 3 ml of 3N HNO 3 , 3 ml of 3N H 2 SO 4 and 0.3 ml of 10% H 2 O 2 by heating in a quartz flask equipped with a reflux condenser. Cool the solution obtained, add 0.02M CyDTA solution in excess and neutralize to pH 3 with 2N NaOH solution. Boil the solution for several minutes to ensure the formation of the metal chelate. After cooling, adjust the pH exactly to 6.7 with 0.5 M NaHCO 3 solution, and then determine the metal concentration by back-titrating the excess CyDTA with 0.01M ZnSO 4 solution using MTB as an indicator. After the titration is over, make the solution to pH 3 with 2N H 2 SO 4 and boil for several minutes to expel CO 2 . Cool the solution, adjust the pH exactly to 7.0 with 0.1N CO 2 -free NaOH solution and add 5 g of mannite and ten drops of 0.1% phenolphthalein solution. Finally, titrate the mannite-boric acid complex with 0.05N NaOH solution until the pink tinge is observed (pH 8.2). (2) Al-boride: Fuse 10 to 30 mg of a sample with a mixture of 1.5 g of Na 2 CO 3 and 0.3 g of KNO 3 in a nickel crucible. Digest the melt with water and filter off the residue (nickel oxide). Add 0.01 M EDTA solution in excess to the filterate and make it to pH 3 with 2N H 2 SO 4 . Analytical Results obtained by the present method agree well with those by other methods. The present method takes only 40 minutes, whereas several hours are required to determine metal and boron by other methods. (auth.)

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...

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

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)

pH-metric solubility. 2: correlation between the acid-base titration and the saturation shake-flask solubility-pH methods.

Science.gov (United States)

Avdeef, A; Berger, C M; Brownell, C

2000-01-01

The objective of this study was to compare the results of a normal saturation shake-flask method to a new potentiometric acid-base titration method for determining the intrinsic solubility and the solubility-pH profiles of ionizable molecules, and to report the solubility constants determined by the latter technique. The solubility-pH profiles of twelve generic drugs (atenolol, diclofenac.Na, famotidine, flurbiprofen, furosemide, hydrochlorothiazide, ibuprofen, ketoprofen, labetolol.HCl, naproxen, phenytoin, and propranolol.HCl), with solubilities spanning over six orders of magnitude, were determined both by the new pH-metric method and by a traditional approach (24 hr shaking of saturated solutions, followed by filtration, then HPLC assaying with UV detection). The 212 separate saturation shake-flask solubility measurements and those derived from 65 potentiometric titrations agreed well. The analysis produced the correlation equation: log(1/S)titration = -0.063(+/- 0.032) + 1.025(+/- 0.011) log(1/S)shake-flask, s = 0.20, r2 = 0.978. The potentiometrically-derived intrinsic solubilities of the drugs were: atenolol 13.5 mg/mL, diclofenac.Na 0.82 microg/mL, famotidine 1.1 mg/ mL, flurbiprofen 10.6 microg/mL, furosemide 5.9 microg/mL, hydrochlorothiazide 0.70 mg/mL, ibuprofen 49 microg/mL, ketoprofen 118 microg/mL, labetolol.HCl 128 microg/mL, naproxen 14 microg/mL, phenytoin 19 microg/mL, and propranolol.HCl 70 microg/mL. The new potentiometric method was shown to be reliable for determining the solubility-pH profiles of uncharged ionizable drug substances. Its speed compared to conventional equilibrium measurements, its sound theoretical basis, its ability to generate the full solubility-pH profile from a single titration, and its dynamic range (currently estimated to be seven orders of magnitude) make the new pH-metric method an attractive addition to traditional approaches used by preformulation and development scientists. It may be useful even to discovery

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.

[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.

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.

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.

Combination of Continuous Dexmedetomidine Infusion with Titrated Ultra-Low-Dose Propofol-Fentanyl for an Awake Craniotomy

Science.gov (United States)

Das, Samaresh; Al-Mashani, Ali; Suri, Neelam; Salhotra, Neeraj; Chatterjee, Nilay

2016-01-01

An awake craniotomy is a continuously evolving technique used for the resection of brain tumours from the eloquent cortex. We report a 29-year-old male patient who presented to the Khoula Hospital, Muscat, Oman, in 2016 with a two month history of headaches and convulsions due to a space-occupying brain lesion in close proximity with the left motor cortex. An awake craniotomy was conducted using a scalp block, continuous dexmedetomidine infusion and a titrated ultra-low-dose of propofolfentanyl. The patient remained comfortable throughout the procedure and the intraoperative neuropsychological tests, brain mapping and tumour resection were successful. This case report suggests that dexmedetomidine in combination with titrated ultra-low-dose propofolfentanyl are effective options during an awake craniotomy, ensuring optimum sedation, minimal disinhibition and a rapid recovery. To the best of the authors’ knowledge, this is the first awake craniotomy conducted successfully in Oman. PMID:27606116

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.

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...

Rapid Inpatient Titration of Intravenous Treprostinil for Pulmonary Arterial Hypertension: Safe and Tolerable.

Science.gov (United States)

El-Kersh, Karim; Ruf, Kathryn M; Smith, J Shaun

There is no standard protocol for intravenous treprostinil dose escalation. In most cases, slow up-titration is performed in the outpatient setting. However, rapid up-titration in an inpatient setting is an alternative that provides opportunity for aggressive treatment of common side effects experienced during dose escalation. In this study, we describe our experience with inpatient rapid up-titration of intravenous treprostinil. This was a single-center, retrospective study in which we reviewed the data of subjects with pulmonary arterial hypertension treated at our center who underwent inpatient rapid up-titration of intravenous treprostinil. Our treprostinil dose escalation protocol included initiation at 2 ng·kg·min with subsequent up-titration by 1 ng·kg·min every 6 to 8 hours as tolerated by side effects. A total of 16 subjects were identified. Thirteen subjects were treprostinil naive (naive group), and 3 subjects were receiving subcutaneous treprostinil but were hospitalized for further intravenous up-titration of treprostinil dose (nonnaive group). In the naive group, the median maximum dose achieved was 20 ng·kg·min with an interquartile range (IQR) of 20-23 ng·kg·min. The median up-titration interval was 6 days (IQR: 4-9). In the nonnaive group, the median maximum dose achieved was 20 ng·kg·min (range: 17-30). The median up-titration interval was 8.5 days (range: 1.5-11). Overall, the median maximum dose achieved was 20 ng·kg·min (IQR: 20-23.5), and the median up-titration interval was 6 days (IQR: 4.6-9.25), with no reported significant adverse hemodynamic events. In patients with pulmonary arterial hypertension, rapid inpatient titration of intravenous treprostinil is safe and tolerable.

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...

Efficacy of daytime continuous positive airway pressure titration in severe obstructive sleep apnoea.

Science.gov (United States)

Rudkowski, J C; Verschelden, P; Kimoff, R J

2001-09-01

The aim of this study was to evaluate manual nasal continuous positive airway pressure (nCPAP) titration during daytime polysomnography compared with conventional overnight titration for patients with severe obstructive sleep apnoea. Thirty-two patients who underwent daytime titration were retrospectively matched (for age, sex, body mass index and apnoea/hypopnoea index (AHI)) to a group titrated overnight during the same period. Successful titration was defined as the identification of the nCPAP level (effective nCPAP (Peff)) required to eliminate respiratory events during all sleep stages. After 3 months of therapy on nCPAP at Peff, nCPAP utilization history was obtained and a group of patients underwent a repeat polysomnogram (PSG) and completed a follow-up Epworth Sleepiness Scale (ESS) score. Initial titration was successful in 91% of daytime patients and 91% of overnight patients. The success of daytime titration was not related to diagnostic AHI or ESS score. Subjective nCPAP utilization was statistically similar in both groups. On the follow-up PSG, there were no significant differences between daytime (n=11) and overnight (n=11) patients in measures of sleep quality or respiratory disturbance. Both groups demonstrated similar and significant improvements in ESS score. These findings suggest that the effective nasal continuous positive airway pressure can be accurately established during daytime titration in a substantial proportion of severe, symptomatic obstructive sleep apnoea patients.

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)

Dose Titration of Pregabalin in Patients with Painful Diabetic Peripheral Neuropathy: Simulation Based on Observational Study Patients Enriched with Data from Randomized Studies.

Science.gov (United States)

Alexander, Joe; Edwards, Roger A; Manca, Luigi; Grugni, Roberto; Bonfanti, Gianluca; Emir, Birol; Whalen, Edward; Watt, Stephen; Parsons, Bruce

2018-03-01

Achieving a therapeutic response to pregabalin in patients with painful diabetic peripheral neuropathy (pDPN) requires adequate upward dose titration. Our goal was to identify relationships between titration and response to pregabalin in patients with pDPN. Data were integrated from nine randomized, placebo-controlled clinical trials as well as one 6-week open-label observational study conducted by 5808 physicians (2642 patients with pDPN) in standard outpatient settings in Germany. These studies evaluated pregabalin for treatment of pDPN. Using these data, we examined "what if" scenarios using a microsimulation platform that integrates data from randomized and observational sources as well as autoregressive-moving-average with exogenous inputs models that predict pain outcomes, taking into account weekly changes in pain, sleep interference, dose, and other patient characteristics that were unchanging. Final pain levels were significantly different depending on dose changes (P titration regardless of baseline pain severity. Altogether, 78.5% of patients with pDPN had 0-1 dose change, and 15.2% had ≥ 2 dose changes. Simulation demonstrated that the 4.8% of inadequately titrated patients who did not improve/very much improve their pain levels would have benefited from ≥ 2 dose changes. Patient satisfaction with tolerability (range 90.3-96.2%) was similar, regardless of baseline pain severity, number of titrations, or extent of improvement, suggesting that tolerability did not influence treatment response patterns. Upward dose titration reduced pain in patients with pDPN who actually received it. Simulation also predicted pain reduction in an inadequately titrated nonresponder subgroup of patients had they actually received adequate titration. The decision not to uptitrate must have been driven by factors other than tolerability. Pfizer, Inc.

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.

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.

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

Titration of a cytoplasmic polyhedrosis virus by a tissue microculture assay: some applications.

Science.gov (United States)

Belloncik, S; Chagnon, A

1980-01-01

A simple tissue microculture technique was developed for the titration of a cytoplasmic polyhedrosis virus (CPV) from Euxoa scandens. The procedure was similar to the 50% tissue culture infectious dose assay, but a single infected cell, detected by the presence of cytoplasmic polyhedra, was scored rather than the degeneration of cell monolayers. The filtration of CPV suspensions resulted in decreased virus titers under certain conditions. This microculture assay was used to determine the effect of cell disruption methods on virus yields. Sonication of infected cells was more efficient than freeze-thawing for the recovery of nonoccluded virus.

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

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

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.

Standardized Procedure Content And Data Structure Based On Human Factors Requirements For Computer-Based Procedures

International Nuclear Information System (INIS)

Bly, Aaron; Oxstrand, Johanna; Le Blanc, Katya L

2015-01-01

Most activities that involve human interaction with systems in a nuclear power plant are guided by procedures. Traditionally, the use of procedures has been a paper-based process that supports safe operation of the nuclear power industry. However, the nuclear industry is constantly trying to find ways to decrease the human error rate, especially the human errors associated with procedure use. Advances in digital technology make computer-based procedures (CBPs) a valid option that provides further enhancement of safety by improving human performance related to procedure use. The transition from paper-based procedures (PBPs) to CBPs creates a need for a computer-based procedure system (CBPS). A CBPS needs to have the ability to perform logical operations in order to adjust to the inputs received from either users or real time data from plant status databases. Without the ability for logical operations the procedure is just an electronic copy of the paper-based procedure. In order to provide the CBPS with the information it needs to display the procedure steps to the user, special care is needed in the format used to deliver all data and instructions to create the steps. The procedure should be broken down into basic elements and formatted in a standard method for the CBPS. One way to build the underlying data architecture is to use an Extensible Markup Language (XML) schema, which utilizes basic elements to build each step in the smart procedure. The attributes of each step will determine the type of functionality that the system will generate for that step. The CBPS will provide the context for the step to deliver referential information, request a decision, or accept input from the user. The XML schema needs to provide all data necessary for the system to accurately perform each step without the need for the procedure writer to reprogram the CBPS. The research team at the Idaho National Laboratory has developed a prototype CBPS for field workers as well as the

Standardized Procedure Content And Data Structure Based On Human Factors Requirements For Computer-Based Procedures

Energy Technology Data Exchange (ETDEWEB)

Bly, Aaron; Oxstrand, Johanna; Le Blanc, Katya L

2015-02-01

Most activities that involve human interaction with systems in a nuclear power plant are guided by procedures. Traditionally, the use of procedures has been a paper-based process that supports safe operation of the nuclear power industry. However, the nuclear industry is constantly trying to find ways to decrease the human error rate, especially the human errors associated with procedure use. Advances in digital technology make computer-based procedures (CBPs) a valid option that provides further enhancement of safety by improving human performance related to procedure use. The transition from paper-based procedures (PBPs) to CBPs creates a need for a computer-based procedure system (CBPS). A CBPS needs to have the ability to perform logical operations in order to adjust to the inputs received from either users or real time data from plant status databases. Without the ability for logical operations the procedure is just an electronic copy of the paper-based procedure. In order to provide the CBPS with the information it needs to display the procedure steps to the user, special care is needed in the format used to deliver all data and instructions to create the steps. The procedure should be broken down into basic elements and formatted in a standard method for the CBPS. One way to build the underlying data architecture is to use an Extensible Markup Language (XML) schema, which utilizes basic elements to build each step in the smart procedure. The attributes of each step will determine the type of functionality that the system will generate for that step. The CBPS will provide the context for the step to deliver referential information, request a decision, or accept input from the user. The XML schema needs to provide all data necessary for the system to accurately perform each step without the need for the procedure writer to reprogram the CBPS. The research team at the Idaho National Laboratory has developed a prototype CBPS for field workers as well as the

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.

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.)

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.

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

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.

Fast Proton Titration Scheme for Multiscale Modeling of Protein Solutions.

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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.

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

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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.

Differential electrolytic potentiometric titration method for the determination of ciprofloxacin in drug formulations.

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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.

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

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

2014-01-01

adulterants in CS and procedures to isolate ASD from CS matrixes containing these adulterants. The authors describe in this paper utilization of an orthogonal approach to establish the identity of Z1 as sodium hexametaphosphate and to confirm the identity of ASD, including ethanol fractionation, FTIR spectroscopy, differential scanning calorimetry, and NMR spectroscopy. The authors suggest that CAME is a cost-effective and easy to use methodfor detecting certain impurities in CS raw ingredients and recommend that CPC and CAME be used in combination by QC laboratories as a means of effectively deterring the practice of adulterating CS raw materials with the known adulterants ASD and Z1 and/or other non-chondroitin substances that can be separated from CSby CAME and that exhibit CPC titration behavior similar to CS.

[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.

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.

Quantitative determination of acidic groups in functionalized graphene by direct titration

Czech Academy of Sciences Publication Activity Database

Ederer, J.; Janoš, P.; Ecorchard, Petra; Štengl, Václav; Bělčická, Zuzana; Šťastný, Martin; Pop-Georgievski, Ognen; Dohnal, V.

2016-01-01

Roč. 103, JUN (2016), s. 44-53 ISSN 1381-5148 R&D Projects: GA ČR(CZ) GA14-05146S Institutional support: RVO:61388980 ; RVO:61389013 Keywords : Acid-base titration * Carboxylic functional groups * Graphene oxide * Phenolic functional groups * Proton-binding model Subject RIV: CA - Inorganic Chemistry ; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 3.151, year: 2016

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.

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

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

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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.

Combination of Continuous Dexmedetomidine Infusion with Titrated Ultra-Low-Dose Propofol-Fentanyl for an Awake Craniotomy; Case report

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Samaresh Das

2016-08-01

Full Text Available An awake craniotomy is a continuously evolving technique used for the resection of brain tumours from the eloquent cortex. We report a 29-year-old male patient who presented to the Khoula Hospital, Muscat, Oman, in 2016 with a two month history of headaches and convulsions due to a space-occupying brain lesion in close proximity with the left motor cortex. An awake craniotomy was conducted using a scalp block, continuous dexmedetomidine infusion and a titrated ultra-low-dose of propofol-fentanyl. The patient remained comfortable throughout the procedure and the intraoperative neuropsychological tests, brain mapping and tumour resection were successful. This case report suggests that dexmedetomidine in combination with titrated ultra-low-dose propofolfentanyl are effective options during an awake craniotomy, ensuring optimum sedation, minimal disinhibition and a rapid recovery. To the best of the authors’ knowledge, this is the first awake craniotomy conducted successfully in Oman.

An automatic system for acidity determination based on sequential injection titration and the monosegmented flow approach.

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Kozak, Joanna; Wójtowicz, Marzena; Gawenda, Nadzieja; Kościelniak, Paweł

2011-06-15

An automatic sequential injection system, combining monosegmented flow analysis, sequential injection analysis and sequential injection titration is proposed for acidity determination. The system enables controllable sample dilution and generation of standards of required concentration in a monosegmented sequential injection manner, sequential injection titration of the prepared solutions, data collecting, and handling. It has been tested on spectrophotometric determination of acetic, citric and phosphoric acids with sodium hydroxide used as a titrant and phenolphthalein or thymolphthalein (in the case of phosphoric acid determination) as indicators. Accuracy better than |4.4|% (RE) and repeatability better than 2.9% (RSD) have been obtained. It has been applied to the determination of total acidity in vinegars and various soft drinks. The system provides low sample (less than 0.3 mL) consumption. On average, analysis of a sample takes several minutes. Copyright © 2011 Elsevier B.V. All rights reserved.

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

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.

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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

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

A rapid method for infectivity titration of Andes hantavirus using flow cytometry.

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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.

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.

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

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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.

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

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

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

Characterization of acid functional groups of carbon dots by nonlinear regression data fitting of potentiometric titration curves

Science.gov (United States)

Alves, Larissa A.; de Castro, Arthur H.; de Mendonça, Fernanda G.; de Mesquita, João P.

2016-05-01

The oxygenated functional groups present on the surface of carbon dots with an average size of 2.7 ± 0.5 nm were characterized by a variety of techniques. In particular, we discussed the fit data of potentiometric titration curves using a nonlinear regression method based on the Levenberg-Marquardt algorithm. The results obtained by statistical treatment of the titration curve data showed that the best fit was obtained considering the presence of five Brønsted-Lowry acids on the surface of the carbon dots with constant ionization characteristics of carboxylic acids, cyclic ester, phenolic and pyrone-like groups. The total number of oxygenated acid groups obtained was 5 mmol g-1, with approximately 65% (∼2.9 mmol g-1) originating from groups with pKa titrated and initial concentration of HCl solution. Finally, we believe that the methodology used here, together with other characterization techniques, is a simple, fast and powerful tool to characterize the complex acid-base properties of these so interesting and intriguing nanoparticles.

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

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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

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.

Titration and HPLC Characterization of Kombucha Fermentation: A Laboratory Experiment in Food Analysis

Science.gov (United States)

Miranda, Breanna; Lawton, Nicole M.; Tachibana, Sean R.; Swartz, Natasja A.; Hall, W. Paige

2016-01-01

Quantification of the many constituents that make up our food, whether they are desirable (vitamins, antioxidants, nutrients) or undesirable (pesticides, toxins), is one of the most practical applications of chemistry. In this study, kombucha, a popular fermented tea beverage, was analyzed using acid-base titration and high-performance liquid…

Safety and tolerability of different titration rates of retigabine (ezogabine) in patients with partial-onset seizures.

Science.gov (United States)

Biton, Victor; Gil-Nagel, Antonio; Brodie, Martin J; Derossett, Sarah E; Nohria, Virinder

2013-11-01

Retigabine (RTG; international nonproprietary name)/ezogabine (EZG; US adopted name) is an antiepileptic drug (AED) that prolongs neuronal voltage-gated potassium-channel KCNQ2-5 (Kv 7.2-7.5) opening. This double-blind study evaluated different RTG/EZG dose-titration rates. Patients (N=73) with partial-onset seizures receiving concomitant AEDs were randomized to one of three titration groups, all of which were initiated at RTG/EZG 300mg/day divided into three equal doses. Fast-, medium-, and slow-titration groups received dose increments of 150mg/day every 2, 4, and 7 days, respectively, achieving the target dose of 1200mg/day after 13, 25, and 43 days, respectively. Safety assessments were performed throughout. Discontinuation rates due to treatment-emergent adverse events (TEAEs) were numerically higher in the fast- (10/23) and medium- (7/22) titration groups than in the slow-titration group (3/23) but statistical significance was achieved only for the high-titration group compared with the low-titration group (p=0.024). Stratified analysis, with concomitant AEDs divided into enzyme inducers (carbamazepine, phenytoin, oxcarbazepine) or noninducers, showed that the risk of discontinuation due primarily to TEAEs was significantly higher in the fast- (p=0.010) but not in the medium-titration group (p=0.078) when compared with the slow-titration group. Overall, the slow-titration rate appeared to be best tolerated and was used in further efficacy and safety studies with RTG/EZG. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous determination of Hg(II)-Ag(I)-Cd(II) by conductometric titration using the formation of ternary complex

International Nuclear Information System (INIS)

Hayashida, Ichiro; Yoshida, Hitoshi; Taga, Mitsuhiko; Hikime, Seiichiro

1979-01-01

A conductometric determination of Hg(II), Ag(I) and Cd(II) was carried out by using the insoluble ternary complex formation of the metal ions with iodide ion in the presence of 1,10-phenanthroline (phen). Recommended procedure is as follows; An aliquot of sample solution containing (14 -- 29) mg of Hg(II), (8 -- 16) mg of Ag(I), and (9 -- 17) mg of Cd(II) transfered into a 100 ml beaker. Add to acetate buffer and stoichiometric amounts of phen (40% ethanol-water solution). Amounts of nitrate ion which was estimated separately by other titration with 0.1 M Ag(phen) 2 complex (40% ethanol-water solution) are adjusted in the range of (4.0 -- 6.0) mM. The sample solution is titrated with 0.1 M KI standard solution at the rate of 0.20 ml/min or less. The titration curve showed three end-points corresponding to the formation of (1) Hg(phen) 2 I 2 , (2) Ag(phen)I, and (3) Cd(phen) 2 I 2 . The relative standard deviation was less than 0.8%, when the pH value was controlled at 4.0 -- 4.5 (acetate buffer) and the nitrate concentration was adjusted in the range of (4.0 -- 6.0)mM. The effect of diverse ions on the determination was also investigated in detail. (author)

A titration model for evaluating calcium hydroxide removal techniques

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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.

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.

Potentiometric titration curves of aluminium salt solutions and its species conversion in the hydrolysis-polymerization course

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Chenyi Wang

2008-12-01

Full Text Available A new concept of critical point is expounded by analysing the potentiometric titration curves of aluminium salt solutions under the moderate slow rate of base injection. The critical point is defined as the characteristic spot of the Al3+ salt solutions potentiometric titration curve, which is related to the experiment conditions. In addition, the changes of critical points reflect the influence of experiment conditions on the course of the hydrolysis-polymerization and the conversion of hydroxyl polynuclear aluminum species. According to the OH/Al mole ratio, the Al species can be divided into four regions quantitatively by three characteristic points on the titration curves: Part I, Al3+/Ala region, consist chiefly of Al3+ and mononuclear Al; Part II, the small/middle polynuclear Al region, including Al2-Al12; Part III, the large-size polynuclear aluminum region, consistent with predominantly Al13-Al54 and a little sol/gel Al(OH3; Part IV, the dissolving region of sol/gel Alc, only Al(OH 3 (aq or am and Al(OH4- species, which set up a base to study on the hydrolysis-polymerization of Al3+. At the same time, significant effects of total aluminum concentration, temperature, halide ion, silicate radical, and organic acid radical on the titration curves and its critical points were observed. Given the three critical points which demarcating the aluminum forms, we carry out a through investigation into the fundamental regulations of these factors’ influence, and offer a fresh train of thought to study the hydrolysis-polymerization of Al3+ in soil solutions.

Semi-automated uranium analysis by a modified Davies--Gray procedure

International Nuclear Information System (INIS)

Swanson, G.C.

1977-01-01

To rapidly and reliably determine uranium in fuel materials a semi-automated implementation of the Davies-Gray uranium titration was developed. The Davies-Gray method is essentially a three step procedure. First uranium is reduced quantitatively from +6 valence to +4 valence by excess of iron (II) in strong phosphoric acid in the absence of nitrite. Prior to the uranium reduction nitrite is destroyed by addition of sulfamic acid. In the second step iron (II) is selectively oxidized to iron (III) by nitric acid in the presence of Mo (VI) catalyst. Finally after dilution to reduce phosphate concentration, the uranium is titrated to U (VI) by standard dichromate. The original sluggish colorimetric endpoint determination used by Davies and Gray is seldom used since New Brunswick Laboratory discovered that addition of vanadium (IV) just prior to titration sufficiently improves reaction rate to allow a potentiometric endpoint determination. One of the advantages of the Davies-Gray uranium titration is that it is quite specific for uranium, most common impurity elements do not interfere with the analysis, and specifically high levels of Pu, Th, and Fe are tolerated

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.

INDIKATOR TITRASI ASAM-BASA DARI EKSTRAK BUNGA SEPATU (Hibiscus rosa sinensis L Indicator of Acid-Base Titration from the Extract of Hibiscus rosa sinensis L Flower

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Siti Nuryanti

2012-05-01

Full Text Available Titration acid-base needs indicator  to show the change of color on interval of hydrogen exponent/degree of acid (pH. Indicator of synthetic which always be used have disadvantages like chemical pollution,  stock and expensive of pro- duction  cost. The research has been carried out to substitute the synthetic indicator with herbal indicator extracted from flower crown of Hibiscus rosa sinensis L extract. The herbal indicator was extracted from the flower crown Hibiscus rosa sinensis L using a mixture methanol-acetic acid. Then it was evaluated with phenolphthalein and methyl orange(E merck comparer to titration the acid-base, they are strong acid-strong base, weak base-strong acid and weak acid-strong base. The result of research show that herbal indicator  of flower crown Hibiscus rosa sinensis L to show theequivalent point in all titrations give peer result with the comparison. With the research result hoped that indicatortitration acid-base flower crown Hibiscus rosa sinensis L is able to as replace synthetic indicator  (metyl orange andphenolphtalein which always be used before. ABSTRAK Titrasi asam-basa memerlukan indikator untuk menunjukkan perubahan warna pada setiap interval derajad keasaman (pH. Indikator sintetis yang digunakan selama ini mempunyai beberapa kelemahan seperti polusi kimia, ketersediaan dan biaya produksi mahal. Upaya penelitian sudah dilakukan untuk menggantikan indikator sintetis dengan indikator dari ekstrak mahkota bunga sepatu. Indikator herbal tersebut dibuat dengan cara mengekstrak mahkota bunga Hibiscus rosa sinensis L dengan mengunakan pelarut metanol-asam asetat. Kemudian dievaluasi dengan indikator pembanding fenolftalein dan metil oranye (produksi E merck untuk titrasi asam-basa yaitu asam kuat-basa kuat, basa lemah-asam kuat dan asam lemah-basa kuat. Dari hasil penelitian diketahui bahwa indikator dari mahkota bunga sepatu untuk menunjukkan titik ekivalen dalam titrasi tersebut memberikan hasil yang

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.

A study of pH-dependent photodegradation of amiloride by a multivariate curve resolution approach to combined kinetic and acid-base titration UV data.

Science.gov (United States)

De Luca, Michele; Ioele, Giuseppina; Mas, Sílvia; Tauler, Romà; Ragno, Gaetano

2012-11-21

Amiloride photostability at different pH values was studied in depth by applying Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) to the UV spectrophotometric data from drug solutions exposed to stressing irradiation. Resolution of all degradation photoproducts was possible by simultaneous spectrophotometric analysis of kinetic photodegradation and acid-base titration experiments. Amiloride photodegradation showed to be strongly dependent on pH. Two hard modelling constraints were sequentially used in MCR-ALS for the unambiguous resolution of all the species involved in the photodegradation process. An amiloride acid-base system was defined by using the equilibrium constraint, and the photodegradation pathway was modelled taking into account the kinetic constraint. The simultaneous analysis of photodegradation and titration experiments revealed the presence of eight different species, which were differently distributed according to pH and time. Concentration profiles of all the species as well as their pure spectra were resolved and kinetic rate constants were estimated. The values of rate constants changed with pH and under alkaline conditions the degradation pathway and photoproducts also changed. These results were compared to those obtained by LC-MS analysis from drug photodegradation experiments. MS analysis allowed the identification of up to five species and showed the simultaneous presence of more than one acid-base equilibrium.

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

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.

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)

Titulações potenciométricas de cátions metálicos tendo como eletrodo indicador o sistema Cu/Cu(II-EDTA Potentiometric titrations of metal cations with edta using the Cu/Cu(II-EDTA system as indicator electrode

Directory of Open Access Journals (Sweden)

Paulo H. Pereira da Silva

2008-01-01

Full Text Available In potentiometric titrations of metal cations with EDTA the Hg/HgY2- system is usually used to detect the end point. However, the use of mercury has been discouraged in analytical procedures due to its toxicity. In this work the Cu/CuY2- system was used as indicator electrode for potentiometric titrations of some metal cations with EDTA. The solutions of Cu2+, Cd2+, Mn2+, Co2+ and Zn2+ were titrated with Na2EDTA solution in the presence of a small concentration of the CuY2- complex using a copper wire as indicator electrode. The potentiometric titrations with the Cu/CuY2- system showed good correlation when compared with an Hg/HgY2- system.

Development and validation of alternative methods by non-aqueous acid-base titration and derivative ultraviolet spectrophotometry for quantification of sildenafil in raw material and tablets

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Taízia Dutra Silva

2017-04-01

Full Text Available Sildenafil citrate (SILC is a potent phosphodiesterase-5 inhibitor used for erectile dysfunction and pulmonary hypertension. This study shows two simple, fast and alternative analytical methods for SILC determination by non-aqueous titration and by derivative ultraviolet spectrophotometry (DUS in active pharmaceutical ingredient and/or dosage forms. The quantitation method of SILC active pharmaceutical ingredient by non-aqueous acid-base titration was developed using methanol as solvent and 0.1 mol/L of perchloric acid in acetic acid as titrant. The endpoint was potentiometrically detected. The non-aqueous titration method shows satisfactory repeatability and intermediate precision (RSD 0.70-1.09%. The neutralization reaction occurred in the stoichiometric ratio 1:1 in methanol. The determination of SILC active pharmaceutical ingredient or dosage forms by DUS was developed in the linear range from 10 to 40 µg/mL, in 0.01 mol/L HCl, using the first order zero-peak method at λ 256 nm. The DUS method shows selectivity toward tablets excipients, appropriate linearity (R2 0.9996, trueness (recovery range 98.86-99.30%, repeatability and intermediate precision in three concentration levels (RSD 1.17-1.28%; 1.29-1.71%, respectively. Therefore, the methods developed are excellent alternatives to sophisticated instrumental methods and can be easily applied in any pharmaceutical laboratory routine due to simple and fast executions.

Determination of vanadium(V) by direct automatic potentiometric titration with EDTA using a chemically modified electrode as a potentiometric sensor.

Science.gov (United States)

Quintar, S E; Santagata, J P; Cortinez, V A

2005-10-15

A chemically modified electrode (CME) was prepared and studied as a potentiometric sensor for the end-point detection in the automatic titration of vanadium(V) with EDTA. The CME was constructed with a paste prepared by mixing spectral-grade graphite powder, Nujol oil and N-2-naphthoyl-N-p-tolylhydroxamic acid (NTHA). Buffer systems, pH effects and the concentration range were studied. Interference ions were separated by applying a liquid-liquid extraction procedure. The CME did not require any special conditioning before using. The electrode was constructed with very inexpensive materials and was easily made. It could be continuously used, at least two months without removing the paste. Automatic potentiometric titration curves were obtained for V(V) within 5 x 10(-5) to 2 x 10(-3)M with acceptable accuracy and precision. The developed method was applied to V(V) determination in alloys for hip prosthesis.

Quantitative Analysis of Mixtures of Monoprotic Acids Applying Modified Model-Based Rank Annihilation Factor Analysis on Variation Matrices of Spectrophotometric Acid-Base Titrations

Directory of Open Access Journals (Sweden)

Ebrahim Ghorbani-Kalhor

2015-04-01

Full Text Available In the current work, a new version of rank annihilation factor analysis was developedto circumvent the rank deficiency problem in multivariate data measurements.Simultaneous determination of dissociation constant and concentration of monoprotic acids was performed by applying model-based rank annihilation factor analysis on variation matrices of spectrophotometric acid-base titrations data. Variation matrices can be obtained by subtracting first row of data matrix from all rows of the main data matrix. This method uses variation matrices instead of multivariate spectrophotometric acid-base titrations matrices to circumvent the rank deficiency problem in the rank quantitation step. The applicability of this approach was evaluated by simulated data at first stage, then the binary mixtures of ascorbic and sorbic acids as model compounds were investigated by the proposed method. At the end, the proposed method was successfully applied for resolving the ascorbic and sorbic acid in an orange juice real sample. Therefore, unique results were achieved by applying rank annihilation factor analysis on variation matrix and using hard soft model combination advantage without any problem and difficulty in rank determination. Normal 0 false false false EN-US X-NONE AR-SA /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi; mso-bidi-language:AR-SA;}    

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.

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.

Proton and Copper Binding to Humic Acids Analyzed by XAFS Spectroscopy and Isothermal Titration Calorimetry

NARCIS (Netherlands)

Xu, Jinling; Koopal, Luuk K.; Fang, Linchuan; Xiong, Juan; Tan, Wenfeng

2018-01-01

Proton and copper (Cu) binding to soil and lignite-based humic acid (HA) was investigated by combining X-ray absorption fine structure (XAFS) spectroscopy, isothermal titration calorimetry (ITC), and nonideal-competitive-adsorption (NICA) modeling. NICA model calculations and XAFS results showed

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.

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.

A titratable two-step transcriptional amplification strategy for targeted gene therapy based on ligand-induced intramolecular folding of a mutant human estrogen receptor

DEFF Research Database (Denmark)

Chen, Ian Y; Paulmurugan, Ramasamy; Nielsen, Carsten Haagen

2014-01-01

PURPOSE: The efficacy and safety of cardiac gene therapy depend critically on the level and the distribution of therapeutic gene expression following vector administration. We aimed to develop a titratable two-step transcriptional amplification (tTSTA) vector strategy, which allows modulation...... of transcriptionally targeted gene expression in the myocardium. PROCEDURES: We constructed a tTSTA plasmid vector (pcTnT-tTSTA-fluc), which uses the cardiac troponin T (cTnT) promoter to drive the expression of the recombinant transcriptional activator GAL4-mER(LBD)-VP2, whose ability to transactivate the downstream...... induction of myocardial fluc expression. HTV injection of pcTnT-tTSTA-fluc led to negligible long-term hepatic fluc expression, regardless of the raloxifene dose given. CONCLUSIONS: The tTSTA vector strategy can effectively modulate transgene expression in a tissue-specific manner. Further refinement...

A Geochemical Reaction Model for Titration of Contaminated Soil and Groundwater at the Oak Ridge Reservation

Science.gov (United States)

Zhang, F.; Parker, J. C.; Gu, B.; Luo, W.; Brooks, S. C.; Spalding, B. P.; Jardine, P. M.; Watson, D. B.

2007-12-01

This study investigates geochemical reactions during titration of contaminated soil and groundwater at the Oak Ridge Reservation in eastern Tennessee. The soils and groundwater exhibits low pH and high concentrations of aluminum, calcium, magnesium, manganese, various trace metals such as nickel and cobalt, and radionuclides such as uranium and technetium. The mobility of many of the contaminant species diminishes with increasing pH. However, base additions to increase pH are strongly buffered by various precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior and associated geochemical effects is thus critical to evaluate remediation performance of pH manipulation strategies. This study was undertaken to develop a practical but generally applicable geochemical model to predict aqueous and solid-phase speciation during soil and groundwater titration. To model titration in the presence of aquifer solids, an approach proposed by Spalding and Spalding (2001) was utilized, which treats aquifer solids as a polyprotic acid. Previous studies have shown that Fe and Al-oxyhydroxides strongly sorb dissolved Ni, U and Tc species. In this study, since the total Fe concentration is much smaller than that of Al, only ion exchange reactions associated with Al hydroxides are considered. An equilibrium reaction model that includes aqueous complexation, precipitation, ion exchange, and soil buffering reactions was developed and implemented in the code HydroGeoChem 5.0 (HGC5). Comparison of model results with experimental titration curves for contaminated groundwater alone and for soil- water systems indicated close agreement. This study is expected to facilitate field-scale modeling of geochemical processes under conditions with highly variable pH to develop practical methods to control contaminant mobility at geochemically complex sites.

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)

Surface acid-base behaviors of Chinese loess.

Science.gov (United States)

Chu, Zhaosheng; Liu, Wenxin; Tang, Hongxiao; Qian, Tianwei; Li, Shushen; Li, Zhentang; Wu, Guibin

2002-08-15

Acid-base titration was applied to investigate the surface acid-base properties of a Chinese loess sample at different ionic strengths. The acidimetric supernatant was regarded as the system blank of titration to correct the influence of particle dissolution on the estimation of proton consumption. The titration behavior of the system blank could be described by the hydrolysis of Al3+ and Si(OH)4 in aqueous solution as well as the production of hydroxyaluminosilicates. The formation of Al-Si species on homogeneous surface sites by hydrous aluminum and silicic acid, released from solid substrate during the acidic titration, was considered in the model description of the back-titration procedure. A surface reaction model was suggested as follows: >SOHSO(-)+H+, pK(a)(int)=3.48-3.98;>SOH+Al(3+)+H4SiO4SOAl(OSi(OH)3(+)+2H+, pK(SC)=3.48-4.04. Two simple surface complexation models accounted for the interfacial structure, i.e., the constant capacitance model (CCM) and the diffuse layer model (DLM), and gave a satisfactory description of the experimental data. Considering the effect of ionic strength on the electrostatic profile at the solid-aqueous interface, the DLM was appropriate at the low concentrations (0.01 and 0.005 mol/L) of background electrolyte (NaNO3 in this study), while the CCM was preferable in the case of high ionic strength (0.1 mol/L).

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

Homemade Equipment for the Teaching of Electrochemistry at Advanced Level: Part III.

Science.gov (United States)

Chan, K. M.

1985-01-01

Describes: (1) thermometric titrations; (2) EM-5 equipment (consisting of a thermal sensor, calorimeter, and input-buffered amplifier); (3) acid-base titrations; (4) precipitation titrations; and (5) redox titrations. Detailed procedures are included. (JN)

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.

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.

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.)

Determination of concentration and molar absorptivity of hypochlorous acid and hypobromous acid species by hydrogen peroxide titration

Science.gov (United States)

Uehara, H.; Arakaki, T.

2017-12-01

Hypochlorous acid and hypobromous acid (abbreviated as "HypoX acids") are the main ingredients of bleaching and bactericides. The HypoX acids change their chemical forms depending on environmental factors such as pH and various chemical reactions. For example, it has been reported that hypobromite ion in water changes to carcinogenic bromate by photochemical reaction with ultraviolet light. In this study, concentrations of HypoX acids were determined by UV-VIS absorbance measurement utilizing the fact that HypoX acids react with hydrogen peroxide and do not co-exist in the solution. The method for determining the concentration by titration with hydrogen peroxide can be carried out simpler and more efficiently than the DPD method or the current titration method generally used for chlorine concentration measurement. Molar absorptivity between 250 - 500 nm of HypoX acids, including their conjugate base species, was determined by solving theoretical acid-base formula including molar fraction of each chemical species at various pHs. Molar absorptivity of OCl- and OBr- between 250 - 500 nm was determined based on the concentrations obtained from titration with hydrogen peroxide and absorbance at pH > 10, where OCl- and OBr- dominate. Furthermore, the HypoX acids solutions were irradiated with a solar simulator, and the photolysis rate constants were obtained. Based on those values, the half-lives were calculated and the behavior of HypoX acids in the environment was elucidated.

Model of Procedure Usage – Results from a Qualitative Study to Inform Design of Computer-Based Procedures

Energy Technology Data Exchange (ETDEWEB)

Johanna H Oxstrand; Katya L Le Blanc

2012-07-01

The nuclear industry is constantly trying to find ways to decrease the human error rate, especially the human errors associated with procedure use. As a step toward the goal of improving procedure use performance, researchers, together with the nuclear industry, have been looking at replacing the current paper-based procedures with computer-based procedure systems. The concept of computer-based procedures is not new by any means; however most research has focused on procedures used in the main control room. Procedures reviewed in these efforts are mainly emergency operating procedures and normal operating procedures. Based on lessons learned for these previous efforts we are now exploring a more unknown application for computer based procedures - field procedures, i.e. procedures used by nuclear equipment operators and maintenance technicians. The Idaho National Laboratory, the Institute for Energy Technology, and participants from the U.S. commercial nuclear industry are collaborating in an applied research effort with the objective of developing requirements and specifications for a computer-based procedure system to be used by field operators. The goal is to identify the types of human errors that can be mitigated by using computer-based procedures and how to best design the computer-based procedures to do this. The underlying philosophy in the research effort is “Stop – Start – Continue”, i.e. what features from the use of paper-based procedures should we not incorporate (Stop), what should we keep (Continue), and what new features or work processes should be added (Start). One step in identifying the Stop – Start – Continue was to conduct a baseline study where affordances related to the current usage of paper-based procedures were identified. The purpose of the study was to develop a model of paper based procedure use which will help to identify desirable features for computer based procedure prototypes. Affordances such as note taking, markups

Simultaneous determination of thermodynamic and kinetic parameters of aminopolycarbonate complexes of cobalt(II) and nickel(II) based on isothermal titration calorimetry data.

Science.gov (United States)

Tesmar, Aleksandra; Wyrzykowski, Dariusz; Muñoz, Eva; Pilarski, Bogusław; Pranczk, Joanna; Jacewicz, Dagmara; Chmurzyński, Lech

2017-04-01

The influence of the different side chain residues on the thermodynamic and kinetic parameters for complexation reactions of the Co 2 + and Ni 2 + ions has been investigated by using the isothermal titration calorimetry (ITC) technique supported by potentiometric titration data. The study was concerned with the 2 common tripodal aminocarboxylate ligands, namely, nitrilotriacetic acid and N-(2-hydroxyethyl) iminodiacetic acid. Calorimetric measurements (ITC) were run in the 2-(N-morpholino)ethanesulfonic acid hydrate (2-(N-morpholino) ethanesulfonic acid), piperazine-N,N'-bis(2-ethanesulfonic acid), and dimethylarsenic acid buffers (0.1 mol L -1 , pH 6) at 298.15 K. The quantification of the metal-buffer interactions and their incorporation into the ITC data analysis enabled to obtain the pH-independent and buffer-independent thermodynamic parameters (K, ΔG, ΔH, and ΔS) for the reactions under study. Furthermore, the kinITC method was applied to obtain kinetic information on complexation reactions from the ITC data. Correlations, based on kinetic and thermodynamic data, between the kinetics of formation of Co 2 + and Ni 2 + complexes and their thermodynamic stabilities are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

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

Detecting Levels of Polyquaternium-10 (PQ-10) via Potentiometric Titration with Dextran Sulphate and Monitoring the Equivalence Point with a Polymeric Membrane-Based Polyion Sensor.

Science.gov (United States)

Ferguson, Stephen A; Wang, Xuewei; Meyerhoff, Mark E

2016-08-07

Polymeric quaternary ammonium salts (polyquaterniums) have found increasing use in industrial and cosmetic applications in recent years. More specifically, polyquaternium-10 (PQ-10) is routinely used in cosmetic applications as a conditioner in personal care product formulations. Herein, we demonstrate the use of potentiometric polyion-sensitive polymeric membrane-based electrodes to quantify PQ-10 levels. Mixtures containing both PQ-10 and sodium lauryl sulfate (SLS) are used as model samples to illustrate this new method. SLS is often present in cosmetic samples that contain PQ-10 (e.g., shampoos, etc.) and this surfactant species interferes with the polyion sensor detection chemistry. However, it is shown here that SLS can be readily separated from the PQ-10/SLS mixture by use of an anion-exchange resin and that the PQ-10 can then be titrated with dextran sulphate (DS). This titration is monitored by potentiometric polyanion sensors to provide equivalence points that are directly proportional to PQ-10 concentrations.

A nine-point pH titration method to determine low-concentration VFA in municipal wastewater.

Science.gov (United States)

Ai, Hainan; Zhang, Daijun; Lu, Peili; He, Qiang

2011-01-01

Characterization of volatile fatty acid (VFA) in wastewater is significant for understanding the wastewater nature and the wastewater treatment process optimization based on the usage of Activated Sludge Models (ASMs). In this study, a nine-point pH titration method was developed for the determination of low-concentration VFA in municipal wastewater. The method was evaluated using synthetic wastewater containing VFA with the concentration of 10-50 mg/l and the possible interfering buffer systems of carbonate, phosphate and ammonium similar to those in real municipal wastewater. In addition, the further evaluation was conducted through the assay of real wastewater using chromatography as reference. The results showed that the recovery of VFA in the synthetic wastewater was 92%-102 and the coefficient of variance (CV) of reduplicate measurements 1.68%-4.72%. The changing content of the buffering substances had little effect on the accuracy of the method. Moreover, the titration method was agreed with chromatography in the determination of VFA in real municipal wastewater with R(2)= 0.9987 and CV =1.3-1.7. The nine-point pH titration method is capable of satisfied determination of low-concentration VFA in municipal wastewater.

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.

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...

Precise coulometric titration of uranium in a high-purity uranium metal and in uranium compounds

International Nuclear Information System (INIS)

Tanaka, Tatsuhiko; Yoshimori, Takayoshi

1975-01-01

Uranium in uranyl nitrate, uranium trioxide and a high-purity uranium metal was assayed by the coulometric titration with biamperometric end-point detection. Uranium (VI) was reduced to uranium (IV) by solid bismuth amalgam in 5M sulfuric acid solution. The reduced uranium was reoxidized to uranium (VI) with a large excess of ferric ion at a room temperature, and the ferrous ion produced was titrated with the electrogenerated manganese(III) fluoride. In the analyses of uranium nitrate and uranium trioxide, the results were precise enough when the error from uncertainty in water content in the samples was considered. The standard sample of pure uranium metal (JAERI-U4) was assayed by the proposed method. The sample was cut into small chips of about 0.2g. Oxides on the metal surface were removed by the procedure shown by National Bureau of Standards just before weighing. The mean assay value of eleven determinations corrected for 3ppm of iron was (99.998+-0.012) % (the 95% confidence interval for the mean), with a standard deviation of 0.018%. The proposed coulometric method is simple and permits accurate and precise determination of uranium which is matrix constituent in a sample. (auth.)

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.

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.

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...

[Determination of total protein content in soya-bean milk via visual moving reaction boundary titration].

Science.gov (United States)

Guo, Chengye; Wang, Houyu; Zhang, Lei; Fan, Liuyin; Cao, Chengxi

2013-11-01

A visual, rapid and accurate moving reaction boundary titration (MRBT) method was used for the determination of the total protein in soya-bean milk. During the process, moving reaction boundary (MRB) was formed by hydroxyl ions in the catholyte and soya-bean milk proteins immobilized in polyacrylamide gel (PAG), and an acid-base indicator was used to denote the boundary motion. The velocity of MRB has a relationship with protein concentration, which was used to obtain a standard curve. By paired t-test, there was no significant difference of the protein content between MRBT and Kjeldahl method at 95% confidence interval. The procedure of MRBT method required about 10 min, and it had linearity in the range of 2.0-14.0 g/L, low limit of detection (0.05 g/L), good precision (RSD of intra-day < 1.90% and inter-day < 4.39%), and high recoveries (97.41%-99.91%). In addition, non-protein nitrogen (NPN) such as melamine added into the soya-bean milk had weak influence on MRBT results.

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.

General procedure for the determination of trace amounts of iodine in natural water samples of unknown composition by spectrophotometric titration

International Nuclear Information System (INIS)

Pesavento, M.; Profumo, A.

1985-01-01

Concentrated hydrochloric acid is added to samples of natural waters containing 2 x 10 -7 to 5 x 10 -5 M iodine and the solutions are then oxidised with hydrogen peroxide on a boiling water-bath. They are then reduced with sodium sulphite, which is subsequently removed by bubbling a stream of inert gas through the solution. All of the inorganic iodine, now present in the solution in the -1 oxidation state, can be titrated spectrophotometrically with standard potassium iodate solution, following a method previously described in which interferences from oxidants and reductants are eliminated. (author)

General procedure for the determination of trace amounts of iodine in natural water samples of unknown composition by spectrophotometric titration

Energy Technology Data Exchange (ETDEWEB)

Pesavento, M.; Profumo, A. (Pavia Univ. (Italy). Dip. di Chimica Generale)

1985-02-01

Concentrated hydrochloric acid is added to samples of natural waters containing 2 x 10/sup -7/ to 5 x 10/sup -5/ M iodine and the solutions are then oxidised with hydrogen peroxide on a boiling water-bath. They are then reduced with sodium sulphite, which is subsequently removed by bubbling a stream of inert gas through the solution. All of the inorganic iodine, now present in the solution in the -1 oxidation state, can be titrated spectrophotometrically with standard potassium iodate solution, following a method previously described in which interferences from oxidants and reductants are eliminated.

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

Calculating Equilibrium Constants in the SnCl2-H2O-NaOH System According to Potentiometric Titration Data

Science.gov (United States)

Maskaeva, L. N.; Fedorova, E. A.; Yusupov, R. A.; Markov, V. F.

2018-05-01

The potentiometric titration of tin chloride SnCl2 is performed in the concentration range of 0.00009-1.1 mol/L with a solution of sodium hydroxide NaOH. According to potentiometric titration data based on modeling equilibria in the SnCl2-H2O-NaOH system, basic equations are generated for the main processes, and instability constants are calculated for the resulting hydroxo complexes and equilibrium constants of low-soluble tin(II) compounds. The data will be of interest for specialists in the field of theory of solutions.

Error causes in the determination of the acid-base reactivity of oxi-hydroxides

International Nuclear Information System (INIS)

Duc, M.; Lefevre, G.; Fedoroff, M.

2004-01-01

The long term safety of radioactive waste depositories is based on the sorption of radionuclides from underground water onto engineered and natural barriers. For a quantitative prediction of the migration in such barriers, we need accurate sorption data. Models should be in agreement with the sorption mechanism. Surface complexation is the most often used model for oxides and hydroxides. In fact, there are several types of surface complexation models such as 1-pK and 2-pK monosite, 1-pK and 2-pK multisite, pK-distribution models. Furthermore, there are several ways to describe the distribution of the electrostatic potential in the vicinity of the solid surface (CCM, DLM, BSM, TLM,..). However, all these models are based on the acid-base properties of superficial hydroxide or oxide groups of the solid. It is necessary to determine the surface charge versus pH (titration curves), the point of zero charge (pzc), the surface density of sites active towards protons and hydroxides in aqueous solutions, the acid-base constants of these sites. These parameters are then used for calculating the sorption constants of ions other than protons and hydroxide ions. It is therefore important to determine these parameters very accurately. A comparison of acid-base parameters published in the literature shows a large scatter for the ''same'' oxides [1,2]. Several causes could explain this scatter. One reason is the use of different models, each electrostatic models leading to different values of site density and constants. However, titration curves and pzc are independent of the model chosen. Another reason may be uncontrolled differences in the composition and purity of oxides. Finally, other causes could be found in the titration procedure, in the solubility and the stability of the solid. In order to understand more about the acid-base properties of oxides and about the origin of the discrepancies between measurements, we have performed a systematic experimental study of several

Hydrolysis-precipitation studies of aluminum (III) solutions. I. Titration of acidified aluminum nitrate solutions

NARCIS (Netherlands)

Vermeulen, A.C.; Geus, John W.; Stol, R.J.; Bruyn, P.L. de

Acidified aluminum nitrate solutions were titrated with alkali (NaOH or KOH) over a temperature range of 24°C to 90°C. A homogeneous distribution of added base was achieved by: (i) in situ decomposition of urea (90°C); and (ii) a novel method involving injection through a capillary submerged in the

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.

STUDENT MISCONCEPTION ON REDOX TITRATION (A CHALLENGE ON THE COURSE IMPLEMENTATION THROUGH COGNITIVE DISSONANCE BASED ON THE MULTIPLE REPRESENTATIONS

Directory of Open Access Journals (Sweden)

H. R. Widarti

2016-04-01

Full Text Available The misconception is one of the obstacles in the concept mastery that needed to be minimalized. This descriptive study was conducted to find the patterns of misconceptions which have occurred on college students who participating in the redox titration course subject. Efforts to minimize misconceptions have been conducted through lectures using the multiple representations with the cognitive dissonance strategies on the 30 students who joined the Fundamentals of Analytical Chemistry course. The research instrument used in this study was 6 multiple-choice tests with reasons. In order to detect the misconception, Certainty of Response Index technique was performed. The preliminary study results showed that 34.30% of students experiencing the misconceptions on redox titration. After treatments, the misconceptions reduced to 28.17%. A misconception that cannot be eliminated was related to the concepts involving in the microscopic and symbolic appearances.

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.

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...

Sequence characteristics required for cooperative binding and efficient in vivo titration of the replication initiator protein DnaA in E. coli

DEFF Research Database (Denmark)

Hansen, Flemming G.; Christensen, Bjarke Bak; Atlung, Tove

2007-01-01

Plasmids carrying the mioC promoter region, which contains two DnaA boxes, R5 and R6 with one misfit to the consensus TT(A)/(T)TNCACA, are as efficient in in vivo titration of the DnaA protein as plasmids carrying a replication-inactivated oriC region with its eight DnaA boxes. Three additional Dna......A boxes around the promoter proximal R5 DnaA box were identified and shown by mutational analysis to be necessary for the cooperative binding of DnaA required for titration. These four DnaA boxes are located in the same orientation and with a spacing of two or three base-pairs. The cooperative binding...... was eliminated by insertion of half a helical turn between any of the DnaA boxes. Titration strongly depends on the presence and orientation of the promoter distal R6 DnaA box located 104 bp upstream of the R5 box as well as neighbouring sequences downstream of R6. Titration depends on the integrity of a 43 bp...

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.

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…

Plutonium estimation in the process solutions and oxide dissolved audit samplers by potentiometry using memo titrator

International Nuclear Information System (INIS)

Kumaraguru, K.; Shukla, Y.D.; Vijayan, K.; Ramamoorthy, N.; Jambunathan, U.; Kapoor, S.C.

1990-01-01

Potentiometric method is employed by using memotitrator coupled with combined electrode for the estimation of plutonium. The estimations are carried out on the process samples and the acid dissolved samples for auditing, in the concentration range of 5 g/l to 20 g/l. The chemical procedure is: i)oxidising plutonium to higher oxidation state by silver oxide, ii)reducing the same by adding excess ferrous, and iii)titrating potassium dichromate against the unreacted ferrous. The plutonium content is computed from ferrous consumed in the reaction. The average percentage error of the method is +/-0.27. The values obtained are in close agreement with those obtained by coulometry. (author)

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

Radiometric determination of anionic surfactants by two-phase titration method with the use of sup(131)I-Rose Bengal as indicator

International Nuclear Information System (INIS)

Lengyel, J.; Krtil, J.

1986-01-01

A radiometric variant of the two-phase titration method for the determination of anionic surfactants of nonsoapy type is described. The method is based on the titration of an anionic surfactant with Septonex in alkaline medium in the presence of sup(131)I-Rose Bengal (sup(131)I-RB). The ion associates are extracted into chloroform. The equivalence point is determined graphically from the activity of sup(131)I-RB-Septonex associate, which is formed after the consumption of the anionic surfactant and passes into the organic phase. The influence of sup(131)I-RB amount, pH of the titrated medium and of soap on the precision of anionic surfactant determination was studied. The detection limit is 2.88 μg sodium n-dodecylsulfate in 10 ml of sample. (author)

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

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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.

Use of linear regression for the processing of curves of differential potentiometric titration of a binary mixture of heterovalent ions using precipitation reactions

International Nuclear Information System (INIS)

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

2003-01-01

A method is proposed for the computer processing of curve of differential potentiometric titration of a binary mixture of heterovalent ions using precipitation reactions. The method is based on the transformation of the titration curve to segment-line characteristics, whose parameters (within the accuracy of the least-squares method) determine the sequence of the equivalence points and solubility products of the resulting precipitation. The method is applied to the titration of Ag(I)-Cd)II), Hg(II)-Te(IV), and Cd(II)-Te(IV) mixtures by a sodium diethyldithiocarbamate solution with membrane sulfide and glassy carbon indicator electrodes. For 4 to 11 mg of the analyte in 50 ml of the solution, RSD varies from 1 to 9% [ru

Oxygen titration strategies in chronic neonatal lung disease.

Science.gov (United States)

Primhak, Robert

2010-09-01

The history of oxygen therapy in neonatology has been littered with error. Controversies remain in a number of areas of oxygen therapy, including targets and strategies in supplemental oxygen therapy in Chronic Neonatal Lung Disease (CNLD). This article reviews some of these controversies, and makes some recommendations based on the available evidence. In graduates of neonatal units who are left with CNLD, oxygen saturation should be kept above 93-95%, with levels below 90% being avoided as far as possible. Titration of oxygen should be done using oximetry recordings which include periods of different activities. Weaning of oxygen supplementation should only be done based on satisfactory recordings during a trial of a lower flow. There is insufficient evidence to say whether weaning for increasing hours a day or stepwise weaning to a continuous lower flow is a better method. Copyright 2010 Elsevier Ltd. All rights reserved.

Pilot study of a new device to titrate oxygen flow in hypoxic patients on long-term oxygen therapy.

Science.gov (United States)

Cirio, Serena; Nava, Stefano

2011-04-01

The O(2) Flow Regulator (Dima, Bologna, Italy) is a new automated oxygen regulator that titrates the oxygen flow based on a pulse-oximetry signal to maintain a target S(pO(2)). We tested the device's safety and efficacy. We enrolled 18 subjects with chronic lung disease, exercise-induced desaturation, and on long-term oxygen therapy, in a randomized crossover study with 2 constant-work-load 15-min cycling exercise tests, starting with the patient's previously prescribed usual oxygen flow. In one test the oxygen flow was titrated manually by the respiratory therapist, and in the other test the oxygen flow was titrated by the O(2) Flow Regulator, to maintain an S(pO(2)) of 94%. We measured S(pO(2)) throughout each test, the time spent by the respiratory therapist to set the device or to manually regulate the oxygen flow, and the total number of respiratory-therapist titration interventions during the trial. There were no differences in symptoms or heart rate between the exercise tests. Compared to the respiratory-therapist-controlled tests, during the O(2) Flow Regulator tests S(pO(2)) was significantly higher (95 ± 2% vs 93 ± 3%, P = .04), significantly less time was spent below the target S(pO(2)) (171 ± 187 s vs 340 ± 220 s, P less respiratory therapist time (5.6 ± 3.7 min vs 2.0 ± 0.1 min, P = .005). The O(2) Flow Regulator may be a safe and effective alternative to manual oxygen titration during exercise in hypoxic patients. It provided stable S(pO(2)) and avoided desaturations in our subjects.

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

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

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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.

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)

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

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.

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

Radiometric titration of officinal radiopharmaceuticals using radioactive kryptonates as end-point indicators. II

International Nuclear Information System (INIS)

Harangozo, M.; Jombik, J.; Schiller, P.; Toelgyessy, J.

1981-01-01

A method for the determination of citric, tartaric and undecylenic acids based on radiometric titration with 0.1 or 0.05 mole.l -1 NaOH was developed. As an indicator of the end point, radioactive kryptonate of glass was used. Experimental technique, results of determinations as well as other possible applications of the radioactive kryptonate of glass for end point determination in alkalimetric analyses of officinal pharmaceuticals are discussed. (author)

A simple and rapid Hepatitis A Virus (HAV titration assay based on antibiotic resistance of infected cells: evaluation of the HAV neutralization potency of human immune globulin preparations

Directory of Open Access Journals (Sweden)

Kaplan Gerardo G

2008-12-01

Full Text Available Abstract Background Hepatitis A virus (HAV, the causative agent of acute hepatitis in humans, is an atypical Picornaviridae that grows poorly in cell culture. HAV titrations are laborious and time-consuming because the virus in general does not cause cytopathic effect and is detected by immunochemical or molecular probes. Simple HAV titration assays could be developed using currently available viral construct containing selectable markers. Results We developed an antibiotic resistance titration assay (ARTA based on the infection of human hepatoma cells with a wild type HAV construct containing a blasticidin (Bsd resistance gene. Human hepatoma cells infected with the HAV-Bsd construct survived selection with 2 μg/ml of blasticidin whereas uninfected cells died within a few days. At 8 days postinfection, the color of the pH indicator phenol red in cell culture media correlated with the presence of HAV-Bsd-infected blasticidin-resistant cells: an orange-to-yellow color indicated the presence of growing cells whereas a pink-to-purple color indicated that the cells were dead. HAV-Bsd titers were determined by an endpoint dilution assay based on the color of the cell culture medium scoring orange-to-yellow wells as positive and pink-to-purple wells as negative for HAV. As a proof-of-concept, we used the ARTA to evaluate the HAV neutralization potency of two commercially available human immune globulin (IG preparations and a WHO International Standard for anti-HAV. The three IG preparations contained comparable levels of anti-HAV antibodies that neutralized approximately 1.5 log of HAV-Bsd. Similar neutralization results were obtained in the absence of blasticidin by an endpoint dilution ELISA at 2 weeks postinfection. Conclusion The ARTA is a simple and rapid method to determine HAV titers without using HAV-specific probes. We determined the HAV neutralization potency of human IG preparations in 8 days by ARTA compared to the 14 days required by the

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)

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

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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.

A rapid Q-PCR titration protocol for adenovirus and helper-dependent adenovirus vectors that produces biologically relevant results

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Gallaher, Sean D.; Berk, Arnold J.

2013-01-01

Adenoviruses are employed in the study of cellular processes and as expression vectors used in gene therapy. The success and reproducibility of these studies is dependent in part on having accurate and meaningful titers of replication competent and helper-dependent adenovirus stocks, which is problematic due to the use of varied and divergent titration protocols. Physical titration methods, which quantify the total number of viral particles, are used by many, but are poor at estimating activity. Biological titration methods, such as plaque assays, are more biologically relevant, but are time consuming and not applicable to helper-dependent gene therapy vectors. To address this, a protocol was developed called “infectious genome titration” in which viral DNA is isolated from the nuclei of cells ~3 h post-infection, and then quantified by Q-PCR. This approach ensures that only biologically active virions are counted as part of the titer determination. This approach is rapid, robust, sensitive, reproducible, and applicable to all forms of adenovirus. Unlike other Q-PCR-based methods, titers determined by this protocol are well correlated with biological activity. PMID:23624118

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.

Determinação de ferro (III em produtos farmacêuticos por titulação fotométrica - doi: 10.4025/actascihealthsci.v33i1.8034 Determination of iron (III in pharmaceutical products by photometric titration - doi: 10.4025/actascihealthsci.v33i1.8034

Directory of Open Access Journals (Sweden)

Flávio Luís Beltrame

2011-05-01

Full Text Available Este trabalho descreve a montagem de um sistema de titulação fotométrica simples e de baixo custo para a determinação de ferro (III em produtos farmacêuticos. O sistema de titulação fotométrica foi construído utilizando-se a bomba peristáltica de um espectrofotômetro convencional. O procedimento é baseado na titulação de ferro (III com EDTA e ácido salicílico como indicador. A absorção do complexo ferro (III-ácido salicílico foi monitorada espectrofotometricamente em 525 nm. O limite de quantificação foi de 5 µg de ferro (III. O procedimento de titulação fotométrica foi aplicado para a determinação de ferro (III em amostras contendo sulfato ferroso e hidróxido férrico polimaltosado. O procedimento mostrou sensibilidade, reprodutibilidade e precisão para a utilização em análise rotineira de ferro (III em produtos farmacêuticos.This paper describes a simple, precise and low-cost photometric titration method for iron (III determination in pharmaceutical preparations. The photometric titration system was constructed using the peristaltic pump of a conventional spectrophotometer. The method is based on titration of iron (III with EDTA using salicylic acid as indicator. The absorption of the iron (III-salicylic acid complex was monitored spectrophotometrically at 525 nm. The limit of quantification was 5 µg of iron (III. The photometric titration procedure was applied for the determination of iron (III in samples of ferrous sulfate and ferric hydroxide polymaltose complex. The procedure showed sensibility, reproducibility and accuracy for use as a method for the routine analysis of iron (III in pharmaceutical formulations.

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

The uncertainty evaluation of measurement for uranium in UF_6 hydrolysate by potentiometric titration

International Nuclear Information System (INIS)

Jiang Haiying; Cheng Ruoyu; Meng Xiujun

2014-01-01

Based on the building of mathematical model, this paper analyzed the origin of component of indeterminacy of which the measurement result for uranium in uranium hexafluoride hydrolysate by potentiometric titration, also each uncertainty was calculated and the expanded uncertainty was given. By evaluation the result of the uranium concentration is that: (158.88 + 1.22) mgU/mL, K = 2, P = 95%. (authors)

[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.

Determination of hydroxide in the presence of aluminate using a modified potentiometric titration

International Nuclear Information System (INIS)

Hanson, T.J.

1975-11-01

A procedure for the determination of hydroxide concentration in the presence of aluminate and other interfering ions was developed using the method of standard additions (or more specifically in this case, standard subtractions). The procedure called for titration with a strong acid which was added in equal increments at regular time intervals. The potential was recorded after each addition of acid. The data was plotted on Gran's Plot Paper, which is based on work done originally by Gran, or it was entered into a computer to determine the equivalence volume of the titrant. When used on many different samples in different matrices, the method gave results that were approximately 100 +- 1 percent of the calculated value. This was shown to be true even in systems containing aluminate [Al(OH) 4 - ], phosphate (PO 4 3- ), sulfate (SO 4 2- ), nitrate (NO 3 - ), nitrite (NO 2 - ), carbonate (CO 3 2- ), and other ions. The effect of these ions was shown to be negligible if the initial OH - concentration was at least 10 -3 M and barium chloride (BaCl 2 ) was added to complex the PO 4 3- and CO 3 2- ions. These ions were checked at levels of up to 3 M for Al(OH) 4 - and NO 3 - , 2 M for NO 2 - , and 1 M for SO 4 2- , PO 4 3- , and CO 3 2- . The method is applicable to radioactive as well as nonradioactive samples and any heat involved with a radioactive sample is insufficient to cause an error in the determination. On the basis of the work performed it was shown that the method was general enough to be run on a routine basis

Reference test methods for total water in lint cotton by Karl Fischer Titration and low temperature distillation

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In a study of comparability of total water contents (%) of conditioned cottons by Karl Fischer Titration (KFT) and Low Temperature Distillation (LTD) reference methods, we demonstrated a match of averaged results based on a large number of replications and weighing the test specimens at the same tim...

The Sound and Feel of Titrations: A Smartphone Aid for Color-Blind and Visually Impaired Students

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Bandyopadhyay, Subhajit; Rathod, Balraj B.

2017-01-01

An Android-based application has been developed to provide color-blind and visually impaired students a multisensory perception of color change observed in a titration. The application records and converts the color information into beep sounds and vibration pulses, which are generated by the smartphone. It uses a range threshold of hue and…

Applying computer-based procedures in nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Mauro V. de; Carvalho, Paulo V.R. de; Santos, Isaac J.A.L. dos; Grecco, Claudio H.S. [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Instrumentacao e Confiabilidade Humana], e-mail: mvitor@ien.gov.br, e-mail: paulov@ien.gov.br, e-mail: luquetti@ien.gov.br, e-mail: grecco@ien.gov.br; Bruno, Diego S. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola Politecnica. Curso de Engenharia de Controle e Automacao], e-mail: diegosalomonebruno@gmail.com

2009-07-01

Plant operation procedures are used to guide operators in coping with normal, abnormal or emergency situations in a process control system. Historically, the plant procedures have been paper-based (PBP), with the digitalisation trend in these complex systems computer-based procedures (CBPs) are being developed to support procedure use. This work shows briefly the research on CBPs at the Human-System Interface Laboratory (LABIHS). The emergency operation procedure EOP-0 of the LABIHS NPP simulator was implemented in the ImPRO CBP system. The ImPRO system was chosen for test because it is available for download in the Internet. A preliminary operation test using the implemented procedure in the CBP system was realized and the results were compared to the operation through PBP use. (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.

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.

Limitations of pH-potentiometric titration for the determination of the degree of deacetylation of chitosan.

Science.gov (United States)

Balázs, Nándor; Sipos, Pál

2007-01-15

The degree of deacetylation (DDA) of chitosan determines the biopolymer's physico-chemical properties and technological applications. pH-Potentiometric titration seems to offer a simple and convenient means of determining DDA. However, to obtain accurate pH-potentiometric DDA values, several factors have to be taken into consideration. We found that the moisture content of the air-dry chitosan samples can be as high as 15%, and a reasonable fraction of this humidity cannot be removed by ordinary drying. Corrections have to be made for the ash content, as in some samples it can be as high as 1% by weight. The method of equivalence point determination was also found to cause systematic variations in the results and in some samples extra acid as high as 1 mol% of the free amino content was also identified. To compensate for the latter effect, the second equivalence point of the titration has to be determined separately and the analytical concentration of the acid be corrected for it. All the corrections listed here are necessary to obtain DDA values that are in reasonable agreement with those obtained from (1)H NMR and IR spectroscopic measurements. The need for these corrections severely limits the usefulness of pH-metry for determining accurate DDA values and thus potentiometry is hardly able to compete with other standard spectroscopic procedures, that is, (1)H NMR spectroscopy.

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.

Office-based procedures for diagnosis and treatment of esophageal pathology.

Science.gov (United States)

Wellenstein, David J; Schutte, Henrieke W; Marres, Henri A M; Honings, Jimmie; Belafsky, Peter C; Postma, Gregory N; Takes, Robert P; van den Broek, Guido B

2017-09-01

Diagnostic and therapeutic office-based procedures under topical anesthesia are emerging in the daily practice of laryngologists and head and neck surgeons. Since the introduction of the transnasal esophagoscope, office-based procedures for the esophagus are increasingly performed. We conducted a systematic review of literature on office-based procedures under topical anesthesia for the esophagus. Transnasal esophagoscopy is an extensively investigated office-based procedure. This procedure shows better patient tolerability and equivalent accuracy compared to conventional transoral esophagoscopy, as well as time and cost savings. Secondary tracheoesophageal puncture, esophageal dilatation, esophageal sphincter injection, and foreign body removal are less investigated, but show promising results. With the introduction of the transnasal esophagoscope, an increasing number of diagnostic and therapeutic office-based procedures for the esophagus are possible, with multiple advantages. Further investigation must prove the clinical feasibility and effectiveness of the therapeutic office-based procedures. © 2017 Wiley Periodicals, Inc.

Repeated dose titration versus age-based method in electroconvulsive therapy: a pilot study.

Science.gov (United States)

Aten, Jan Jaap; Oudega, Mardien; van Exel, Eric; Stek, Max L; van Waarde, Jeroen A

2015-06-01

In electroconvulsive therapy (ECT), a dose titration method (DTM) was suggested to be more individualized and therefore more accurate than formula-based dosing methods. A repeated DTM (every sixth session and dose adjustment accordingly) was compared to an age-based method (ABM) regarding treatment characteristics, clinical outcome, and cognitive functioning after ECT. Thirty-nine unipolar depressed patients dosed using repeated DTM and 40 matched patients treated with ABM were compared. Montgomery-Åsberg Depression Rating Scale (MADRS) and Mini-Mental State Examination (MMSE) were assessed at baseline and at the end of the index course, as well as the total number of ECT sessions. Both groups were similar regarding age, sex, psychotic features, mean baseline MADRS, and median baseline MMSE. At the end of the index course, the two methods showed equal outcome (mean end MADRS, 11.6 ± 8.3 in DTM and 9.5 ± 7.6 in ABM (P = 0.26); median end MMSE, 28 (25-29) and 28 (25-29.8), respectively (P = 0.81). However, the median number of all ECT sessions differed 16 (11-22) in DTM versus 12 (10-14.8) in ABM; P = 0.02]. Using regression analysis, dosing method and age were independently associated with the total number of ECT sessions, with less sessions needed in ABM (P = 0.02) and in older patients (P = 0.001). In this comparative cohort study, ABM and DTM showed equal outcome for depression and cognition. However, the median ECT course duration in repeated DTM appeared longer. Additionally, higher age was associated with shorter ECT courses regardless of the dosing method. Further prospective studies are needed to confirm these findings.

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

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.

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.

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)

The MacDonald and savage titrimetric procedure for plutonium scaled-down to the milligram level: Automated procedure for routine analysis of safeguards samples containing 2 to 5 mg plutonium

International Nuclear Information System (INIS)

Ronesch, K.; Jammet, G.; Berger, J.; Doubek, N.; Bagliano, G.; Deron, S.

1992-08-01

A selective titrimetric procedure directly applicable to both input and product solutions from fast reactor fuel reprocessing was set up by MacDonald and Savage and scaled down to 3 mg of plutonium in sample aliquots at the request of the Safeguards Analytical Laboratory (SAL) of the International Atomic Energy Agency (IAEA), which needed to replace its silver (II) oxide titration procedure by a more selective electrochemical method. Although the procedure is very selective the following species still interfere: Vanadates (almost quantitatively), Neptunium (one electron exchange per mole); Nitrites, Fluorosilicates and Iodates present in mg amount yield slight biases. This paper describes the fully automatized procedure presently applied in SAL for the routine determination of 2 to 5 mg plutonium dissolved in nitric acid solution. The method allows the unattended analysis of 20 aliquots within a five hour period. The equipment including the reagent distribution system, the sample changer and the control units are introduced and the principle design of the software is shortly described. Safety requirements have been addressed and are also reviewed in the report. Results obtained on standard reference materials, international intercomparison samples and actual safeguards samples routinely analyzed with the proposed procedure are presented and compared with results achieved with the semiautomatic mode to demonstrate the performance. International requirements to reduce the amount of radioactive materials in waste will certainly lead to a further reduction of the amount of plutonium in one aliquot. Some future perspective to titrate 1 mg samples are presented in the discussion. 12 refs, 10 figs, 8 tabs

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.

Use of EDTA for potentiometric back titration of rare earths and analysis of their mixtures

International Nuclear Information System (INIS)

Zayed, M.A.; Rizk, M.S.; Khalifa, H.; Omer, W.F.

1987-01-01

Advantage was taken of the stoichiometric reaction between mercury(II), rare earths, alkaline earths, heavy metal ions and EDTA in urotropine buffered media to determine rare earths by back-titration of excess EDTA in the course of estimating a variety of lanthanides or analysing their binary mixture with one of the alkaline earth metals by selective control of pH; or analysing their binary mixtures with heavy metals using fluoride as a good masking agent for rare earths; or analysing their ternary mixtures with both heavy and alkaline earth metals in two steps, one by selective control of pH and the other by masking of rare earths with fluoride at lower pH to estimate the heavy metal. The procedures given are simple, rapid and extremely reliable. 19 refs. (author)

An online computer method for the potentiometric titration of mixtures of a strong and a weak acid

NARCIS (Netherlands)

Bos, M.

1977-01-01

A PDP-11 online computer method for the titration of mixtures or a strong and a weak acid is described.The method is based on multiparametric curve-fitting. One or the parameters found from the calculations is the dissociation constant of the weak acid, hence the method can be applied even when this

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)

Determining procedures for simulation-based training in radiology

DEFF Research Database (Denmark)

Nayahangan, Leizl Joy; Nielsen, Kristina Rue; Albrecht-Beste, Elisabeth

2018-01-01

, and basic abdominal ultrasound. CONCLUSION: A needs assessment identified and prioritized 13 technical procedures to include in a simulation-based curriculum. The list may be used as guide for development of training programs. KEY POINTS: • Simulation-based training can supplement training on patients......OBJECTIVES: New training modalities such as simulation are widely accepted in radiology; however, development of effective simulation-based training programs is challenging. They are often unstructured and based on convenience or coincidence. The study objective was to perform a nationwide needs...... assessment to identify and prioritize technical procedures that should be included in a simulation-based curriculum. METHODS: A needs assessment using the Delphi method was completed among 91 key leaders in radiology. Round 1 identified technical procedures that radiologists should learn. Round 2 explored...

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)

A simple, versatile and sensitive cell-based assay for prions from various species.

Directory of Open Access Journals (Sweden)

Zaira E Arellano-Anaya

Full Text Available Detection and quantification of prion infectivity is a crucial step for various fundamental and applied aspects of prion research. Identification of cell lines highly sensitive to prion infection led to the development of cell-based titration procedures aiming at replacing animal bioassays, usually performed in mice or hamsters. However, most of these cell lines are only permissive to mouse-adapted prions strains and do not allow titration of prions from other species. In this study, we show that epithelial RK13, a cell line permissive to mouse and bank vole prion strains and to natural prion agents from sheep and cervids, enables a robust and sensitive detection of mouse and ovine-derived prions. Importantly, the cell culture work is strongly reduced as the RK13 cell assay procedure designed here does not require subcultivation of the inoculated cultures. We also show that prions effectively bind to culture plastic vessel and are quantitatively detected by the cell assay. The possibility to easily quantify a wider range of prions, including rodent experimental strains but also natural agents from sheep and cervids, should prompt the spread of cell assays for routine prion titration and lead to valuable information in fundamental and applied studies.

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

Science.gov (United States)

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

Computer-Based Procedures for Field Workers in Nuclear Power Plants: Development of a Model of Procedure Usage and Identification of Requirements

Energy Technology Data Exchange (ETDEWEB)

Katya Le Blanc; Johanna Oxstrand

2012-04-01

The nuclear industry is constantly trying to find ways to decrease the human error rate, especially the human errors associated with procedure use. As a step toward the goal of improving procedure use performance, researchers, together with the nuclear industry, have been looking at replacing the current paper-based procedures with computer-based procedure systems. The concept of computer-based procedures is not new by any means; however most research has focused on procedures used in the main control room. Procedures reviewed in these efforts are mainly emergency operating procedures and normal operating procedures. Based on lessons learned for these previous efforts we are now exploring a more unknown application for computer based procedures - field procedures, i.e. procedures used by nuclear equipment operators and maintenance technicians. The Idaho National Laboratory and participants from the U.S. commercial nuclear industry are collaborating in an applied research effort with the objective of developing requirements and specifications for a computer-based procedure system to be used by field workers. The goal is to identify the types of human errors that can be mitigated by using computer-based procedures and how to best design the computer-based procedures to do so. This paper describes the development of a Model of Procedure Use and the qualitative study on which the model is based. The study was conducted in collaboration with four nuclear utilities and five research institutes. During the qualitative study and the model development requirements and for computer-based procedures were identified.

TitGer: uma planilha eletrônica para simulação de titulação de mistura de compostos polipróticos TitGer: an electronic worksheet for simulating the titration of a mixture of polyprotic species

Directory of Open Access Journals (Sweden)

André Fernando Oliveira

2007-02-01

Full Text Available The aim of this paper is to present a simple way of treating the general equation for acid-base titrations based on the concept of degree of dissociation, and to propose a new spreadsheet approach for simulating the titration of mixtures of polyprotic compounds. The general expression, without any approximation, is calculated a simple iteration method, making number manipulation easy and painless. The user-friendly spreadsheet was developed by using MS-Excel and Visual-Basic-for-Excel. Several graphs are drawn for helping visualizing the titration behavior. A Monte Carlo function for error simulation was also implemented. Two examples for titration of alkalinity and McIlvaine buffer are presented.

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.

Determination of rhenium (7) trace amounts by spectrophotometric titration in medium of mixed solvents

International Nuclear Information System (INIS)

Kuznetsov, V.V.; Samorukova, O.L.

1978-01-01

The method has been proposed of determining rhenium (7) microamounts by spectrophotometric titration in the medium water-dimethyl-sulphoxide with the reagent nitrochromazo. The method is based on the formation of ionic pairs K + ReO 4 - in water-organic solvents. The results of rhenium determination are satisfactory in a wide concentration range up to 0.3 mkg in 15 ml which makes the method proposed close in sensitivity to photometric methods and much better in reproducibility

Subject-driven titration of biphasic insulin aspart 30 twice daily is non-inferior to investigator-driven titration in Chinese patients with type 2 diabetes inadequately controlled with premixed human insulin: A randomized, open-label, parallel-group, multicenter trial.

Science.gov (United States)

Yang, Wenying; Zhu, Lvyun; Meng, Bangzhu; Liu, Yu; Wang, Wenhui; Ye, Shandong; Sun, Li; Miao, Heng; Guo, Lian; Wang, Zhanjian; Lv, Xiaofeng; Li, Quanmin; Ji, Qiuhe; Zhao, Weigang; Yang, Gangyi

2016-01-01

The present study was to compare the efficacy and safety of subject-driven and investigator-driven titration of biphasic insulin aspart 30 (BIAsp 30) twice daily (BID). In this 20-week, randomized, open-label, two-group parallel, multicenter trial, Chinese patients with type 2 diabetes inadequately controlled by premixed/self-mixed human insulin were randomized 1:1 to subject-driven or investigator-driven titration of BIAsp 30 BID, in combination with metformin and/or α-glucosidase inhibitors. Dose adjustment was decided by patients in the subject-driven group after training, and by investigators in the investigator-driven group. Eligible adults (n = 344) were randomized in the study. The estimated glycated hemoglobin (HbA1c) reduction was 14.5 mmol/mol (1.33%) in the subject-driven group and 14.3 mmol/mol (1.31%) in the investigator-driven group. Non-inferiority of subject-titration vs investigator-titration in reducing HbA1c was confirmed, with estimated treatment difference -0.26 mmol/mol (95% confidence interval -2.05, 1.53) (-0.02%, 95% confidence interval -0.19, 0.14). Fasting plasma glucose, postprandial glucose increment and self-measured plasma glucose were improved in both groups without statistically significant differences. One severe hypoglycemic event was experienced by one subject in each group. A similar rate of nocturnal hypoglycemia (events/patient-year) was reported in the subject-driven (1.10) and investigator-driven (1.32) groups. There were 64.5 and 58.1% patients achieving HbA1c titration of BIAsp 30 BID was as efficacious and well-tolerated as investigator-titration. The present study supported patients to self-titrate BIAsp 30 BID under physicians' supervision.

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.

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.

Office-Based Procedures for the Diagnosis and Treatment of Laryngeal Pathology.

Science.gov (United States)

Wellenstein, David J; Schutte, Henrieke W; Takes, Robert P; Honings, Jimmie; Marres, Henri A M; Burns, James A; van den Broek, Guido B

2017-09-18

Since the development of distal chip endoscopes with a working channel, diagnostic and therapeutic possibilities in the outpatient clinic in the management of laryngeal pathology have increased. Which of these office-based procedures are currently available, and their clinical indications and possible advantages, remains unclear. Review of literature on office-based procedures in laryngology and head and neck oncology. Flexible endoscopic biopsy (FEB), vocal cord injection, and laser surgery are well-established office-based procedures that can be performed under topical anesthesia. These procedures demonstrate good patient tolerability and multiple advantages. Office-based procedures under topical anesthesia are currently an established method in the management of laryngeal pathology. These procedures offer medical and economic advantages compared with operating room-performed procedures. Furthermore, office-based procedures enhance the speed and timing of the diagnostic and therapeutic process. Copyright © 2017 The Voice Foundation. All rights reserved.

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)

Developing and Demonstrating an Augmented Reality Colorimetric Titration Tool