Sample records for pyridylazoresorcinol
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(2-PYRIDYLAZO)RESORCINOL FOR FLOTATION
African Journals Online (AJOL)
KEY WORDS: Iron(II), Fe-PAR complex, Flotation, Spectrophotometry, Soils, Zinc sulfide concentrates. INTRODUCTION. 4-(2-Pyridylazo)resorcinol (PAR) is one of the most popular analytical reagents. It forms colored complexes with many metal ions and can be used for their spectrophotometric determination. A well-known ...
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Racheva, Petya Vassileva; Gavazov, Kiril Blazhev; Lekova, Vanya Dimitrova; Dimitrov, Atanas Nikolov
2013-01-01
Complex formation and liquid-liquid extraction were studied in a system containing cobalt(II), 4-(2-pyridylazo)resorcinol (PAR), 1,4-diphenyl-3-(phenylamino)-1H-1,2,4-triazole (Nitron, Nt), water, and chloroform. The effect of some experimental parameters (pH, shaking time, concentration of PAR, and concentration of Nt) was systematically investigated, and the optimum conditions for cobalt extraction as an ion-association complex, (NtH+)[Co3+(PAR)2], were found. The following key equilibrium ...
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Directory of Open Access Journals (Sweden)
Divarova Vidka V.
2015-01-01
Full Text Available The formation and liquid-liquid extraction of ion-association complexes between Co(II-4-(2-Pyridylazoresorcinol (PAR anionic chelates and cations of three ditetrazolium chlorides were studied: Blue Tetrazolium chloride (BTC, Neotetrazolium chloride (NTC and Nitro Blue Tetrazolium chloride (NBT. The optimum conditions for the formation and solvent extraction of the ion-association comlpex chelates were determined. It has been found that in the systems of Co(II-PAR-DTS, the reactants are reacted in molar ratios 1:2:1 and the general formula of complexes was suggested. The extraction equilibria were investigated and quantitatively characterized by the equilibrium constants and the recovery factors. The analytical characteristics of the complexes were calculated.
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Spectrophotometric Determination of Gallium(III with 4-(2-Pyridylazo-resorcinol and Nitron
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Petya Vassileva Racheva
2015-07-01
Full Text Available The formation and liquid-liquid extraction of ion-association complex between gallium(III − 4-(2-pyridylazo-resorcinol (PAR – 1,4-diphenyl-3-(phenylamino-1H-1,2,4-triazole (nitron, Nt, water and chloroform were studied. The optimum conditions for gallium(III extraction as an ion-association complex, (NtH+[Ga3+(PAR2]-, were found: pH, concentration of the reagents and shaking time. The following key constants were calculated: constant of extraction (logKex = 6.28 ± 0.07, constant of association (logβ = 4.98 ± 0.05, constant of distribution (logKD = 1.30 ± 0.02 and recovery factor (R / % = 95.17 ± 0.02. Beerʼs law is obeyed for Ga(III concentration up to 0.8 μg cm-3 with apparent molar absorptivity of (10.3 ± 0.4×104 dm-3 mol-1 cm-1 at λmax = 510 nm. Some additional characteristics, such as limit of detection (LOD = 0.072 μg cm-3, limit of quantification (LOQ = 0.24 μg cm-3 and Sandellʼs sensitivity (SS = 0.000675 ng cm-2 were estimated as well.
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Directory of Open Access Journals (Sweden)
Petya Vassileva Racheva
2013-01-01
Full Text Available Complex formation and liquid-liquid extraction were studied in a system containing cobalt(II, 4-(2-pyridylazoresorcinol (PAR, 1,4-diphenyl-3-(phenylamino-1H-1,2,4-triazole (Nitron, Nt, water, and chloroform. The effect of some experimental parameters (pH, shaking time, concentration of PAR, and concentration of Nt was systematically investigated, and the optimum conditions for cobalt extraction as an ion-association complex, (NtH+[Co3+(PAR2], were found. The following key equilibrium constants were calculated: constant of association (Log β=4.77±0.06, constant of distribution (LogKD=1.34±0.01, and constant of extraction (LogKex=6.11±0.07. Beer’s law was obeyed for Co concentrations up to 1.7 μg mL−1 with a molar absorptivity of 6.0×104 L mol−1 cm−1 at λmax=520 nm. Some additional characteristics, such as limit of detection, limit of quantification, and Sandell’s sensitivity, were estimated as well.
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International Nuclear Information System (INIS)
Kadi, M.W.; El-Shahawi, M.S.
2011-01-01
A simple, fast, low cost, and precise direct β-correction spectrophotometric method was developed for thorium determination in water. The method is based on the reaction of Th(IV) with 4-(2-pyridylazo)-resorcinol (PAR) in aqueous solution of pH 5-6 and measuring the absorbance of the resulting red-colored complex at λ max 497 nm. The effective molar absorptivity of the Th(IV)-PAR complex was 2.52 x 10 4 L mol -1 cm -1 . Beer's law and Ringbom plots were obeyed in the concentration range 0.04-2.0 and 0.07-1.2 μg mL -1 of thorium ions using β-correction spectrophotometry, respectively. The limits of detection and quantification of Th(IV) were 0.02 and 0.066 μg mL -1 , respectively. The developed method was applied for the analysis of thorium in certified reference material (IAEA-soil-7), tap-, underground- and Red-sea water samples. The validation of the method was also tested by comparison with data obtained by ICP-MS. The method is convenient, less sensitive to common interfering species and less laborious than most of published methods. The statistical treatment of data in terms of Student t-tests and variance ratio f-tests has revealed no significance differences. The structure of the Th(IV)-PAR complex was determined with the aid of spectroscopic measurements (UV-Visible and Fourier Transform Infrared Spectroscopy). (author)
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International Nuclear Information System (INIS)
Venezia, M.; Alonzo, G.; Palmisano, L.
2008-01-01
The colour changes of 4-(2-pyridylazo)-resorcinol and naphthol green β as new screening metallochromic indicator in back-titration of EDTA excess with Zn(II) to determine Cr(III)/EDTA complex was investigated with the help of tristimulus colorimetry. Specific colour discrimination (SCD) and L*, a*, b* 1976 parameters were successfully applied to evaluate the quality of colour transition at the end-point in non-alkaline media and in the presence of Zn(II) and Ca(II) which resulted in non-interfering species at 1 x 10 -3 M and 2 x 10 -3 M, respectively. The above concentrations are comparable with those used for Cr(III). Validation of the fast and accurate reported method was performed by atomic absorption spectroscopy. Moreover, the method was applied for determining Cr as Cr(III) in a wastewater effluent deriving from a leather industry
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Energy Technology Data Exchange (ETDEWEB)
Venezia, M.; Alonzo, G. [Dipartimento di Ingegneria e Tecnologie Agro Forestali, Universita degli Studi di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Palmisano, L. [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita degli Studi di Palermo, Viale delle Scienze, 90128 Palermo (Italy)], E-mail: palmisano@dicpm.unipa.it
2008-03-01
The colour changes of 4-(2-pyridylazo)-resorcinol and naphthol green {beta} as new screening metallochromic indicator in back-titration of EDTA excess with Zn(II) to determine Cr(III)/EDTA complex was investigated with the help of tristimulus colorimetry. Specific colour discrimination (SCD) and L*, a*, b* 1976 parameters were successfully applied to evaluate the quality of colour transition at the end-point in non-alkaline media and in the presence of Zn(II) and Ca(II) which resulted in non-interfering species at 1 x 10{sup -3} M and 2 x 10{sup -3} M, respectively. The above concentrations are comparable with those used for Cr(III). Validation of the fast and accurate reported method was performed by atomic absorption spectroscopy. Moreover, the method was applied for determining Cr as Cr(III) in a wastewater effluent deriving from a leather industry.
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International Nuclear Information System (INIS)
Silva, Edson Luiz; Santos Roldan, Paulo dos; Gine, Maria Fernanda
2009-01-01
A procedure for simultaneous separation/preconcentration of copper, zinc, cadmium, and nickel in water samples, based on cloud point extraction (CPE) as a prior step to their determination by inductively coupled plasma optic emission spectrometry (ICP-OES), has been developed. The analytes reacted with 4-(2-pyridylazo)-resorcinol (PAR) at pH 5 to form hydrophobic chelates, which were separated and preconcentrated in a surfactant-rich phase of octylphenoxypolyethoxyethanol (Triton X-114). The parameters affecting the extraction efficiency of the proposed method, such as sample pH, complexing agent concentration, buffer amount, surfactant concentration, temperature, kinetics of complexation reaction, and incubation time were optimized and their respective values were 5, 0.6 mmol L -1 , 0.3 mL, 0.15% (w/v), 50 deg. C, 40 min, and 10 min for 15 mL of preconcentrated solution. The method presented precision (R.S.D.) between 1.3% and 2.6% (n = 9). The concentration factors with and without dilution of the surfactant-rich phase for the analytes ranged from 9.4 to 10.1 and from 94.0 to 100.1, respectively. The limits of detection (L.O.D.) obtained for copper, zinc, cadmium, and nickel were 1.2, 1.1, 1.0, and 6.3 μg L -1 , respectively. The accuracy of the procedure was evaluated through recovery experiments on aqueous samples.
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Application of 4-(2-pyridylazo)resorcinol for flotation ...
African Journals Online (AJOL)
Bulletin of the Chemical Society of Ethiopia. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 30, No 3 (2016) >. Log in or Register to get access to full text downloads.
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A Study of Complexation-ability of Neutral Schiff Bases to Some Metal Cations
Topal, Giray; Tümerdem, Recep; Basaran, Ismet; Gümüş, Arzu; Cakir, Umit
2007-01-01
The constants of the extraction equilibrium and the distribution for dichloromethane as an organic solvent having low dielectric constant of metal cations with chiral Schiff bases, benzaldehydene-(S)-2-amino-3-phenylpropanol (I), ohydroxybenzaldehydene-( S)-2-amino-3-phenyl-propanol (II), benzaldehydene-(S)-2- amino-3-methylbutanol (III) with anionic dyes [4-(2-pyridylazo)-resorcinol mono sodium monohydrate (NaPar), sodium picrat (NaPic) and potassium picrat (KPic)] and some heavy metal chlor...
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Gavazov, Kiril Blazhev; Racheva, Petya Vasileva; Lekova, Vanya Dimitrova; Dimitrov, Atanas Nikolov; Türkyilmaz, Murat; Genç, Fatma
2012-01-01
Several liquid-liquid extraction systems containing vanadium {vanadium(IV) or vanadium(V)}, azoderivative of resorcinol {ADR: 4-(2-pyridylazo)-resorcinol (PAR) or 4-(2-thiazolylazo)-resorcinol (TAR)} and (phenylmethoxibis)tetrazolium salts {MBT: 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)-bis(2,5-diphenyl-2H-tetrazolium) chloride (Blue Tetrazolium, BT) or 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)-bis[2,5-di(4-nitrophenyl)-2H-tetrazolium] chloride (Tetranitroblue Tetrazolium, TNBT)} were studied. The op...
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Photometric determination of niobium in materials with high content of phosphorus
International Nuclear Information System (INIS)
Navrotskaya, V.A.; Aleksandrova, E.I.; Kletenik, Yu.B.
1982-01-01
To determine niobium in various samples of niobium concentrates with a high phosphorus content, a photometric method with pyridylazoresorcinol (PAR) is used. It is shown that all the elements indicated (Fe, Si, Ti, Al, Ca) including phosphorus do not interfere with the niobium determination with the use of PAR. The method has been tried on artificial samples with different content of the base components. Variation coefficient constitutes 4.5%. No systematic errors, due to a high content of any concomitant element, are detected. The determination threshold is 10 - 2 %
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Improved colorimetric determination of serum zinc.
Johnson, D J; Djuh, Y Y; Bruton, J; Williams, H L
1977-07-01
We show how zinc may easily be quantified in serum by first using an optimum concentration of guanidine hydrochloride to cause release of zinc from proteins, followed by complexation of released metals with cyanide. The cyanide complex of zinc is preferentially demasked with chloral hydrate, followed by a colorimetric reaction between zinc and 4-(2-pyridylazo)resorcinol. This is a sensitive water-soluble ligand; its complex with zinc has an absorption maximum at 497 nm. Values found by this technique compare favorably with those obtained by atomic absorption spectroscopy.
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Takahashi, Toru; Kaneko, Emiko; Yotsuyanagi, Takao
2006-12-01
A selective off-line preconcentration technique for the V(V) complex with 4-(2-pyridylazo)resorcinol has been developed and successfully applied to the determination of V(V) in an air-borne sample. The target complex was separated from excess reagent using an ODS cartridge and water as the eluent. The complex was then concentrated on another ODS cartridge using tetrabutylammonium bromide and eluted with methanol; the eluate was applied to a one-drop concentration/HPLC. A detection limit as low as (6.05 +/- 0.82)x 10(-11) M (5 ppt) was achieved.
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Determination of niobium in rocks by an isotope dilution spectrophotometric method
Greenland, L.P.; Campbell, E.Y.
1970-01-01
Rocks and minerals are fused with sodium peroxide in the presence of carrierfree 95Nb. The fusion cake is leached with water and the precipitate dissolved in hydrofluoric-sulfuric acid mixture. Niobium is extracted into methyl isobutyl ketone and further purified by ion exchange. The amount of niobium is determined spectrophotometrically with 4-(2-pyridylazo)-resorcinol, and the chemical yield of the separations determined by counting 95Nb. This procedure is faster and less sensitive to interferences than previously proposed methods for determining niobium in rocks.The high purity of the separated niobium makes the method applicable to nearly all matrices. ?? 1970.
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International Nuclear Information System (INIS)
Kochelaeva, G.A.; Degtyarev, M.Yu.; Ivanov, V.M.; Prokhorova, G.V.; Figurovskaya, V.N.
1999-01-01
The kinetics of complexation in the system molybdenum(6)-azo compound-hydroxylamine was studied. Azo compounds of the types o,o'-dihydroxyazo compounds, such as Lyumogallion IREA and Magneson IREA, and heterocyclic azo compounds, such as 4-(2-pyridylazo)resorcinol and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, were studied. The formation of mixed-ligand complexes with the ratio of component 1 : 1 : 1 was detected. Rate constants, activation energies, and stability constants of the forming compounds were evaluated. It was concluded that the reagents under study are promising for the analytical chemistry of molybdenum [ru
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Herman, K.; Mircescu, N. E.; Szabo, L.; Leopold, L. F.; Chiş, V.; Leopold, N.
2013-05-01
An improved approach for surface-enhanced Raman scattering (SERS) detection of mixture constituents after thin layer chromatography (TLC) separation is presented. A SERS active silver substrate was prepared under open air conditions, directly on the thin silica film by photo-reduction of silver nitrate, allowing the detection of binary mixtures of cresyl violet, bixine, crystal violet, and Cu(II) complex of 4-(2-pyridylazo)resorcinol. The recorded SERS spectrum provides a unique spectral fingerprint for each molecule; therefore the use of analyte standards is avoided, thus rendering the presented procedure advantageous compared to the conventional detection methodology in TLC.
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A Study of Complexation-ability of Neutral Schiff Bases to Some Metal Cations
Directory of Open Access Journals (Sweden)
Umit Cakir
2007-09-01
Full Text Available The constants of the extraction equilibrium and the distribution fordichloromethane as an organic solvent having low dielectric constant of metal cations withchiral Schiff bases, benzaldehydene-(S-2-amino-3-phenylpropanol (I, o- benzaldehydene-(S-2-hydroxybenzaldehydene-(S-2-amino-3-phenyl-propanol (II,amino-3-methylbutanol (III with anionic dyes [4-(2-pyridylazo-resorcinol mono sodiummonohydrate (NaPar, sodium picrat (NaPic and potassium picrat (KPic] and some heavymetal chlorides were determined at 25 oC. All the ligands have given strongestcomplexation for NaPar. In contrast, similar behaviour for both alkali metal picrates is notapparent in the complexation of corresponding ligands.
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International Nuclear Information System (INIS)
Mazzucotelli, A.; Dadone, A.; Frache, R.; Baffi, F.; Genoa Univ.
1982-01-01
A detailed study of isocratic and gradient elution separations of lanthanides has been carried out. Analyses of industrially and scientifically interesting products such as luminescent phosphors have been carried out by gradient elution with DL-2-hydroxyisobutyric acid. The determination of small amounts of terbium in gadolinium oxide sulphide phosphors is described in which an HCl solution was eluted through a stainless steel column packed with microparticulate silica, with bonded cation-exchange groups. Complete separation of gadolinium and terbium is achieved. Detection is with a variable wavelength detector following post-column complex formation with 4-(2-pyridylazo)-resorcinol monosodium salt. Results obtained on test solutions show good reproducilbity and sensitivtiy and the method may be considered sufficiently reliable to be used in routine quality control procedures. (orig.)
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International Nuclear Information System (INIS)
Tajabadi, F.; Sovizi, M.R.; Yamini, Y.
2013-01-01
We report on a method for the extraction of the lanthanide ions La(III), Sm(III), Nd(III) and Pr(III) using a carbon-ferrite magnetic nanocomposite as a new adsorbent, and their determination via flow injection ICP-OES. The lanthanide ions were converted into their complexes with 4-(2-pyridylazo)resorcinol, and these were adsorbed onto the nanocomposite. Fractional factorial design and central composite design were applied to optimize the extraction efficiencies to result in preconcentration factors in the range of 141-246. Linear calibration plots were obtained, the limits of detection (at S/N = 3) are between 0. 5 and 10 μg L -1 , and the intra-day precisions (n = 3) range from 3.1 to 12.8 %. The method was successfully applied to a certified reference material. (author)
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International Nuclear Information System (INIS)
Ohara, A.K.; Farias, P.A.M.
1990-01-01
The development method for uranyl ion determination by the optimization of chemical reaction and instrumental parameters is shown. This method is based on preconcentration stage, where in adsorptive accumulation of metallic complex in a static electrode is presented. (author)
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International Nuclear Information System (INIS)
Quencer, B.M.; Crouch, S.R.
1994-01-01
The application of the extended Kalman filter to multicomponent kinetic data is described. The method is based on obtaining data at multiple wavelengths over time using a linear photodiode array detector. The extended Kalman filter is used to process the data obtained. It is shown that accurate results can be obtained even if the estimated value of the rate constant is not completely accurate or reproducible. No pH, ionic strength, or temperature controls were used in testing the chemical system. A system of three lanthanides reacting with 4-(2-pyridylazo)resorcinol (PAR) was used. Accurate estimates of concentrations were obtained even though the relative rate constants for the reactions of La, Pr, and Nd with PAR were 1:1.7:1.9, and a high degree of spectral overlap is present. 23 refs., 4 figs., 4 tabs
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Tsai, Suh-Jen Jane; Shiue, Chia-Chann; Chang, Shiow-Ing
1997-07-01
The analytical characteristics of copper in nickel-base alloys have been investigated with electrothermal atomic absorption spectrometry. Deuterium background correction was employed. The effects of various chemical modifiers on the analysis of copper were investigated. Organic modifiers which included 2-(5-bromo-2-pyridylazo)-5-(diethylamino-phenol) (Br-PADAP), ammonium citrate, 1-(2-pyridylazo)-naphthol, 4-(2-pyridylazo)resorcinol, ethylenediaminetetraacetic acid and Triton X-100 were studied. Inorganic modifiers palladium nitrate, magnesium nitrate, aluminum chloride, ammonium dihydrogen phosphate, hydrogen peroxide and potassium nitrate were also applied in this work. In addition, zirconium hydroxide and ammonium hydroxide precipitation methods have also been studied. Interference effects were effectively reduced with Br-PADAP modifier. Aqueous standards were used to construct the calibration curves. The detection limit was 1.9 pg. Standard reference materials of nickel-base alloys were used to evaluate the accuracy of the proposed method. The copper contents determined with the proposed method agreed closely with the certified values of the reference materials. The recoveries were within the range 90-100% with relative standard deviation of less than 10%. Good precision was obtained.
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Dakova, Ivanka; Karadjova, Irina; Ivanov, Ivo; Georgieva, Ventsislava; Evtimova, Bisera; Georgiev, George
2007-02-12
Ion-imprinted polymer (IIP) particles are prepared by copolymerization of methacrylic acid as monomer, trimethylolpropane trimethacrylate as crosslinking agent and 2,2'-azo-bis-isobutyronitrile as initiator in the presence of Cu(II), a Cu(II)-4-(2-pyridylazo)resorcinol (Cu(II)-PAR) complex, and PAR only. A batch procedure is used for the determination of the characteristics of the Cu(II) solid phase extraction from the IIP produced. The results obtained show that the Cu(II)-PAR IIP has the greatest adsorption capacity (37.4 micromol g(-1) of dry copolymer) among the IIPs investigated. The optimal pH value for the quantitative preconcentration is 7, and full desorption is achieved by 1 M HNO(3). The selectivity coefficients (S(Cu/Me)) for Me=Ni(II), Co(II) are 45.0 and 38.5, respectively. It is established that Cu(II)-PAR IIPs can be used repeatedly without a considerable adsorption capacity loss. The determination of Cu(II) ions in seawater shows that the interfering matrix does not influence the preconcentration and selectivity values of the Cu(II)-PAR IIPs. The detection and quantification limits are 0.001 micromol L(-1) (3sigma) and 0.003 micromol L(-1) (6sigma), respectively.
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International Nuclear Information System (INIS)
Gordeeva, V.P.; Glazkova, S.V.; Tsysin, G.I.; Ivanov, V.M.; Zolotov, Yu. A.
2003-01-01
The aim of this work was synthesis of new sorption cellulose filters for dynamic preconcentration of Au, Pd and Pt from chloride solutions and subsequent XRF determination of these elements on the filters. New filters were prepared by impregnation of a filter paper with solution of tri-n-octylamine and paraffin in hexane (TOA-filters). The effect of paraffin and TOA concentration in hexane on a content of nitrogen in a filter was studied. It was found that Au(III), Pd(II) and Pt(IV) were quantitatively recovered on the TOA-filters (filtering surface diameter of 23 mm, thickness of 0.15 mm) from 0.5 - 1 M HCl at a flow rates of 2-5 ml min-1 from 10-100 ml of solution. The mathematical model of sorption dynamics was offered for the estimation of potential possibilities of new impregnated sorbents and for the evaluation of optimum dynamic conditions allowing to achieve of maximum concentration efficiency (CE max ). The elements were determined directly on the filters by XRF spectrometer. Palladium was also determined on the TOA-filters after formation of coloured compounds of metal with 4-(2-pyridylazo)resorcinol (PAR) by diffuse reflectance spectroscopy with the calculation of calorimetric characteristics and using test-scale. (authors)
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Development of an airborne lead analysis kit and its application.
Kongtip, Pornpimol; Borisut, Pornchulee; Yoosook, Witaya; Osiri, Pramuk; Rojanavipart, Piangchan
2010-11-01
We developed a method to analyze airborne lead concentrations in the field. It was a modification of the colorimetric method using the reaction between 4(2-pyridylazo)-resorcinol (PAR) and lead with cyanex302 in an acid medium to reduce interfering metals. The lead concentration was detected with a photometer made in Thailand. The developed method uses an impinger containing 1% nitric acid solution as an absorbing agent to collect airborne lead at a flow rate of less than or equal to one liter/minute. Cyanex302 solution in toluene was used to extract metals from the samples and 0.1M nitric acid was used to extract just lead. The lead solution was reacted in 0.5 ml of 0.03% PAR solution, with 1 ml ammonium chloride buffer; the absorption of this solution was measured by a photometer. The results show the limit of detection (LOD) was 0.01 mg/l. The limit of quantification (LOQ) was 0.03 mg/l. The percent recovery of the lead concentrations of 0.05 - 3.0 mg/l was 94.0 to 103.5%. The precision presented as %CV ranged from 0.65 to 10.27%. Lead concentration in a lead smelting factory detected by this method was not significantly different from that detected by the NIOSH method: 7,303 at a 95% confidence level.
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Horstkotte, Burkhard; Jarošová, Patrícia; Chocholouš, Petr; Sklenářová, Hana; Solich, Petr
2015-05-01
In this work, the applicability of Sequential Injection Chromatography for the determination of transition metals in water is evaluated for the separation of copper(II), zinc(II), and iron(II) cations. Separations were performed using a Dionex IonPAC™ guard column (50mm×2mm i.d., 9 µm). Mobile phase composition and post-column reaction were optimized by modified SIMPLEX method with subsequent study of the concentration of each component. The mobile phase consisted of 2,6-pyridinedicarboxylic acid as analyte-selective compound, sodium sulfate, and formic acid/sodium formate buffer. Post-column addition of 4-(2-pyridylazo)resorcinol was carried out for spectrophotometric detection of the analytes׳ complexes at 530nm. Approaches to achieve higher robustness, baseline stability, and detection sensitivity by on-column stacking of the analytes and initial gradient implementation as well as air-cushion pressure damping for post-column reagent addition were studied. The method allowed the rapid separation of copper(II), zinc(II), and iron(II) within 6.5min including pump refilling and aspiration of sample and 1mmol HNO3 for analyte stacking on the separation column. High sensitivity was achieved applying an injection volume of up to 90µL. A signal repeatability of<2% RSD of peak height was found. Analyte recovery evaluated by spiking of different natural water samples was well suited for routine analysis with sub-micromolar limits of detection. Copyright © 2015 Elsevier B.V. All rights reserved.
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An on-line pre-concentration system for determination of cadmium in drinking water using FAAS
International Nuclear Information System (INIS)
Santos, Walter N.L. dos; Costa, Jorge L.O.; Araujo, Rennan G.O.; Jesus, Djane S. de; Costa, Antonio C.S.
2006-01-01
In the present paper, a minicolumn of polyurethane foam loaded with 4-(2-pyridylazo)-resorcinol (PAR) is proposed as pre-concentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. The optimization step was performed using two-level full factorial design and Doehlert matrix, involving the variables: sampling flow rate, elution concentration, buffer concentration and pH. Using the established experimental conditions in the optimization step of: pH 8.2, sampling flow rate 8.5 mL min -1 , buffer concentration 0.05 mol L -1 and elution concentration of 1.0 mol L -1 , this system allows the determination of cadmium with detection limit (LD) (3σ/S) of 20.0 ng L -1 and quantification limit (LQ) (10σ/S) of 64 ng L -1 , precision expressed as relative standard deviation (R.S.D.) of 5.0 and 4.7% for cadmium concentration of 5.0 and 40.0 μg L -1 , respectively, and a pre-concentration factor of 158 for a sample volume of 20.0 mL. The accuracy was confirmed by cadmium determination in the standard reference material, NIST SRM 1643d trace elements in natural water. This procedure was applied for cadmium determination in drinking water samples collected from Salvador City, Bahia, Brazil. For five samples analyzed, the achieved concentrations varied from 0.31 to 0.86 μg L -1
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Metal ion release from metallothioneins: proteolysis as an alternative to oxidation.
Peroza, Estevão A; dos Santos Cabral, Augusto; Wan, Xiaoqiong; Freisinger, Eva
2013-09-01
Metallothioneins (MTs) are among others involved in the cellular regulation of essential Zn(II) and Cu(I) ions. However, the high binding affinity of these proteins requires additional factors to promote metal ion release under physiological conditions. The mechanisms and efficiencies of these processes leave many open questions. We report here a comprehensive analysis of the Zn(II)-release properties of various MTs with special focus on members of the four main subfamilies of plant MTs. Zn(II) competition experiments with the metal ion chelator 4-(2-pyridylazo)resorcinol (PAR) in the presence of the cellular redox pair glutathione (GSH)/glutathione disulfide (GSSG) show that plant MTs from the subfamilies MT1, MT2, and MT3 are remarkably more affected by oxidative stress than those from the Ec subfamily and the well-characterized human MT2 form. In addition, we evaluated proteolytic digestion with trypsin and proteinase K as an alternative mechanism for selective promotion of metal ion release from MTs. Also here the observed percentage of liberated metal ions depends strongly on the MT form evaluated. Closer evaluation of the data additionally allowed deducing the thermodynamic and kinetic properties of the Zn(II) release processes. The Cu(I)-form of chickpea MT2 was used to exemplify that both oxidation and proteolysis are also effective ways to increase the transfer of copper ions to other molecules. Zn(II) release experiments with the individual metal-binding domains of Ec-1 from wheat grain reveal distinct differences from the full-length protein. This triggers the question about the roles of the long cysteine-free peptide stretches typical for plant MTs.
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International Nuclear Information System (INIS)
Li, Jianping; Ma, Fei; Wei, Xiaoping; Fu, Cong; Pan, Hongcheng
2015-01-01
Graphical abstract: A novel molecular imprinted electrochemiluminescence sensor was fabricated for ultra-trace Be 2+ detection with an extremely lower detection limit based on the luminol–H 2 O 2 ECL system. - Highlights: • A novel molecular imprinted electrochemiluminescence sensor was fabricated for ultra-trace Be 2+ detection. • Imprint cavities in the MIPs from elution the Be–PAR complex could provide more recognition sites for analytes. • ECL emission produced by the luminol–H 2 O 2 ECL system, which was applied to detect Be 2+ . • It gave an extremely lower detection limit (2.35 × 10 −11 mol L −1 ) than the reported methods. - Abstract: A new molecularly imprinted electrochemiluminescence (ECL) sensor was proposed for highly sensitive and selective determination of ultratrace Be 2+ determination. The complex of Be 2+ with 4-(2-pyridylazo)-resorcinol (PAR) was chosen as the template molecule for the molecularly imprinted polymer (MIP). In this assay, the complex molecule could be eluted from the MIP, and the cavities formed could then selectively recognize the complex molecules. The cavities formed could also work as the tunnel for the transfer of probe molecules to produce sound responsive signal. The determination was based on the intensity of the signal, which was proportional to the concentrations of the complex molecule in the sample solution, and the Be 2+ concentration could then be determined indirectly. The results showed that in the range of 7 × 10 −11 mol L −1 to 8.0 × 10 −9 mol L −1 , the ECL intensity had a linear relationship with the Be 2+ concentrations, with the limit of detection of 2.35 × 10 −11 mol L −1 . This method was successfully used to detect Be 2+ in real water samples
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International Nuclear Information System (INIS)
Shimizu, Tokuo; Sakai, Kaoru
1981-01-01
The trace amount of vanadium in sea water was determined by graphite furnace atomic absorption spectrometry with a tube coated with pyrolytic graphite. To correct the background absorption, a deuterium lamp with a higher-brilliant thermal cathode was used. The sensitivity for vanadium increased 10 -- 20 fold by the use of the tube coated with pyrolytic graphite, and the utility lifetime of the tube was greatly extended. Vanadium(V) - 4-(2-pyridylazo)resorcinol (PAR) complexes were extracted into chloroform as an ion-pair with benzyldimethyltetradecylammonium (Zephiramine) cation alternatively. The sample of sea water, which was made to 0.1 N in sulfuric acid and 0.1% in hydrogen peroxide, was loaded onto the column of Dowex 1-X 4 resin (SO 4 2- -form). Vanadium was then eluted from the resin with 1 N sulfuric acid-0.1% hydrogen peroxide or 1 N hydrochloric acid-0.1% hydrogen peroxide evaporated to dry. After dissolution of the elute in 0.2 N nitric acid, vanadium was extracted. Secondly, the sample of sea water was adjusted to pH 5.0, and loaded onto the column of Chelex-100 resin. Vanadium was eluted from the resin with 2 N ammonia. The above two methods took much time, but the coprecipitation method was not so and recommended for the determination of vanadium in sea water. Vanadium was coprecipitated with iron(III) hydroxide-hydrous titanium(IV) oxide at pH 6.0. The precipitate was digested with nitric acid-hydrogen peroxide. The solution was diluted to 50 ml with water. The resulting solutions were employed to determine the vanadium concentration by the graphite furnace atomic absorption measurement. The trace amounts of vanadium in various kinds of the coastal sea water were determined by the coprecipitation method. (author)