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Sample records for pyridylazoresorcinol

  1. 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.

  2. Liquid-liquid extraction of ion-association complexes of cobalt(II-4-(2-pyridylazoresorcinol with ditetrazolium salts

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    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.

  3. Immobilization of complexes of some heavy metals with a 2-(4-pyridylazo)-resorcinol 'PAR' on Algerian hydrothermal clay

    Science.gov (United States)

    Bendjeffal, H.; Guerfi, K.; Bouhedja, Y.; Rebbani, N.

    2009-11-01

    The immobilization of the complexes of some heavy metals such as Co(II) and Ni(II) with a 2-(4-pyridylazo)-resorcinol 'PAR' from aqueous solution is studied using a natural and activated kaolin of Hameme Edbegh-Guelma (East of Algeria). The sorption of these metals complexes on kaolin from aqueous medium through the process of adsorption is studied under a set of variables such as concentration of metal complex, amount of kaolin, time and temperature of interaction. The suitability of the adsorbent was tested by fitting the adsorption data with Langmuir and Freundlich isotherms. The sorption of these complexes conformed to linear form of Langmuir adsorption equation. Langmuir qm constants for each metal complex were found as 0.391-0.493 mg/g (NiII-PAR2), 0.129-0.168 mg/g (CoII-PAR2) at 30 ∘C, respectively also, kinetic and thermodynamic parameters such as enthalpy (ΔH), free energy (ΔG) and entropy (ΔS) were calculated and these values show that adsorption of Co(II) and Ni(II) complex on kaolin was an exothermic.

  4. A direct spectrophotometric method for the simultaneous determination of zinc and cobalt in metalloproteins using 4-(2-pyridylazo)resorcinol.

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    Säbel, Crystal E; Shepherd, Jeffrey L; Siemann, Stefan

    2009-08-01

    An assay involving the direct and simultaneous determination of low micromolar concentrations (1-10 microM) of both zinc and cobalt ions suitable for metal content analyses of metalloproteins is described. The procedure exploits differences in the visible absorption spectra of the chromophoric chelator 4-(2-pyridylazo)resorcinol (PAR) resulting from its complexation to Zn2+ and/or Co2+ ions and is based on the fit of experimental spectra to a linear addition of Beer-Lambert law. The method eliminates the need for separating or masking one of the metal ions prior to their quantification and could prove to be particularly useful in studies on Co2+-substituted zinc proteins.

  5. Molar absorption coefficients and stability constants of metal complexes of 4-(2-pyridylazo)resorcinol (PAR): Revisiting common chelating probe for the study of metalloproteins.

    Science.gov (United States)

    Kocyła, Anna; Pomorski, Adam; Krężel, Artur

    2015-11-01

    4-(2-Pyridylazo)resorcinol (PAR) is one of the most popular chromogenic chelator used in the determination of the concentrations of various metal ions from the d, p and f blocks and their affinities for metal ion-binding biomolecules. The most important characteristics of such a sensor are the molar absorption coefficient and the metal-ligand complex dissociation constant. However, it must be remembered that these values are dependent on the specific experimental conditions (e.g. pH, solvent components, and reactant ratios). If one uses these values to process data obtained in different conditions, the final result can be under- or overestimated. We aimed to establish the spectral properties and the stability of PAR and its complexes accurately with Zn(2+), Cd(2+), Hg(2+), Co(2+), Ni(2+), Cu(2+), Mn(2+) and Pb(2+) at a multiple pH values. The obtained results account for the presence of different species of metal-PAR complexes in the physiological pH range of 5 to 8 and have been frequently neglected in previous studies. The effective molar absorption coefficient at 492 nm for the ZnHx(PAR)2 complex at pH7.4 in buffered water solution is 71,500 M(-1) cm(-1), and the dissociation constant of the complex in these conditions is 7.08×10(-13) M(2). To confirm these values and estimate the range of the dissociation constants of zinc-binding biomolecules that can be measured using PAR, we performed several titrations of zinc finger peptides and zinc chelators. Taken together, our results provide the updated parameters that are applicable to any experiment conducted using inexpensive and commercially available PAR.

  6. Simultaneous preconcentration of copper, zinc, cadmium, and nickel in water samples by cloud point extraction using 4-(2-pyridylazo)-resorcinol and their determination by inductively coupled plasma optic emission spectrometry

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    Silva, Edson Luiz, E-mail: edsonqmc@hotmail.com [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario, 303, CP 96, 13416-000 Piracicaba, SP (Brazil); Santos Roldan, Paulo dos [Universidade Federal de Alagoas, Campus A.C. Simoes, Av. Lourival Melo Mota, Tabuleiro do Martins, CEP: 57072-970 AL (Brazil); Gine, Maria Fernanda [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario, 303, CP 96, 13416-000 Piracicaba, SP (Brazil)

    2009-11-15

    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{sup -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 {mu}g L{sup -1}, respectively. The accuracy of the procedure was evaluated through recovery experiments on aqueous samples.

  7. Simultaneous preconcentration of copper, zinc, cadmium, and nickel in water samples by cloud point extraction using 4-(2-pyridylazo)-resorcinol and their determination by inductively coupled plasma optic emission spectrometry.

    Science.gov (United States)

    Silva, Edson Luiz; Roldan, Paulo dos Santos; Giné, Maria Fernanda

    2009-11-15

    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 degrees 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 microg L(-1), respectively. The accuracy of the procedure was evaluated through recovery experiments on aqueous samples.

  8. Simultaneous preconcentration of vanadium(V/IV) species with palmitoyl quinolin-8-ol bonded to amberlite XAD 2 and their separate spectrophotometric determination with 4-(2-pyridylazo)-resorcinol using CDTA as masking agent

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    Filik, Hayati; Berker, Kadriye Isil; Balkis, Nuray; Apak, Resat

    2004-08-02

    This paper reports the simultaneous preconcentration and separation of trace amounts of V species in synthetic solutions and seawater with palmitoyl quinolin-8-ol bonded amberlite XAD 2 copolymer resin column prior to simultaneous speciation analysis. Both V(IV) and V(V) species could be sorbed and preconcentrated by the resin. Both vanadium species were quantitatively eluted together from the resin column using HCl as stripping agent and used for speciation studies. For the speciation analysis of eluted V species, the selected route involved spectrophotometric determination of total vanadium with 4-(2-pyridylazo)-resorcinol (PAR) and vanadate estimation by masking vanadyl with 1,2 cyclohexanediaminetetraacetic acid (CDTA). The preconcentrated V species were assayed spectrophotometrically with PAR at 542 nm, and the results were compared with those of FAAS. The detection limits of V(V) with spectrophotometry and FAAS were 1.6 and 0.9 {mu}g l{sup -1}, respectively. The optimal experimental parameters such as pH, sample flow rate, desorption flow rate, redox behaviour of V(IV) and V(V) in resin and volume of eluent and sample were investigated. The values obtained for the preconcentration factor by the two methods were nearly consistent, and were in the range 150-fold. Analysis of certified reference material (IAEA-405) by the proposed method showed good agreement with the certified value. The established procedure was employed for preconcentrating the vanadium species from artificial and real seawater.

  9. 4-(2-吡啶偶氮)间苯二酚分光光度法测定酸泥中铌%Determination of niobium in acid sludge by 4- (2-pyridylazo)-resorcinol spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    张光华

    2012-01-01

    The conditions for color reaction of 4-(2-pyridineazo)-resorcinol (PAR) with niobium was investigated, and a method for the determination of niobium in acid sludge (which was expressed as niobium pentoxide) by spectrophotometry was developed. The results showed that in the solution at pH 5. 6-6. 0, a red ternary complex was formed by PAR with the complex anion of niobium tartrate in the presence of beryllium salt and tartaric acid, and its maximum absorption wavelength was 550 nm with apparent molar absorptivity (ε) of 2. 6×104 L · mol-1 · cm-1. Under the optimum experimental conditions, there was a good linear relationship between the niobium pentoxide concentration within the range of 0. 02 to 0. 8 μg/mL and its corresponding absorbance, the correlation coefficient (r) was 0. 998 8 and the detection limit was 0. 004 8 μg/mL. The method was used for the determination of niobium in acid sludge. The results were in accordance with those obtained by chlorosulphophenol S spectrophotometry, and the relative standard deviations were 2. l%-2. 5%.%研究了4-(2-吡啶偶氮)间苯二酚(PAR)与铌的显色条件,建立了测定酸泥中铌(以五氧化二铌来表示)含量的分光光度法.结果表明,在pH5.6~6.0的溶液中,在铍盐和酒石酸存在下,PAR与酒石酸铌的络阴离子形成红色三元络合物.该络合物最大吸收波长为550nm,表观摩尔吸光系数ε=2.6×104 L·mol-1·cm-1,在最佳实验条件下,五氧化二铌的浓度与其对应的吸光度在0.02~0.8 μg/mL范围内呈良好的线性关系,相关系数r=0.998 8,检出限为0.004 8μg/mL.方法用于酸泥中铌的测定,结果与氯代磺酚S光度法一致,相对标准偏差为2.1%~2.5%.

  10. 键合4-(2-吡啶偶氮)-间苯二酚螯合树脂分离富集-火焰原子吸收法测定蔬菜中痕量镉(Ⅱ)%Separation and Preconcentration of Trace Cadmium from Vegetables with 4-(2-Pyridylazo)-resorcinol Immobilized on Amberlite XAD-4 Prior to Determination by Flame Atomic Absorption Spectrometry

    Institute of Scientific and Technical Information of China (English)

    李文山; 周方钦; 刘琳; 屈东方

    2012-01-01

    本文合成了Amberlite XAD-4键合4-(2-吡啶偶氮)-间苯二酚螯合树脂,并考察了其对痕量镉(Ⅱ)的吸附性能.探讨了溶液pH、洗脱剂和干扰离子等对镉(Ⅱ)分离富集的影响.树脂吸附容量为4.7 mg/g,吸附的镉(Ⅱ)用5 mL 2 mol/L HNO3乙醇溶液洗脱,火焰原子吸收法测定.在最佳实验条件下,回收率为94.4%~97.9%,相对标准偏差在1.7%~2.7%之间.方法可用于蔬菜中镉(Ⅱ)的测定.%A new method for the determination of trace Cd(II) based on Amberlite XAD-4 bonded with 4-(2-pyridylazo) resorcinol adsorption with flame atomic absorption spectrometry (FAAS) was proposed. In this process,the effects of pH,elution agent, interfering ions and other experimental conditions on separation and preconcentration of trace Cd( II ) were studied. Adsorption capacities of the resin was 4. 7 mg/g. The adsorbed Cd(?) on the resin could be completely eluted with 5 mL of 2 mol/L HNO3 ethanol solution and then determined by FAAS. Under the optimum conditions, the recoveries were in the range from 94. 4% to 97. 9%,and relative standard deviations were between 1. 7% and 2. 7%. The proposed method was applied for the determination of trace Cd( II ) in vegetable with satisfactory results.

  11. Determination of zinc in environmental samples by solid phase spectrophotometry: optimization and validation study

    OpenAIRE

    Molina, Mar??a Francisca; Nechar, Mounir; Bosque-Sendra, Juan M.

    1998-01-01

    A simple and specific solid-phase spectrophotometric (SPS) determination of zinc in ??g dm-3 level has been developed based on the reaction of Zn(II) with 4-(2-pyridylazo)resorcinol (PAR) in the presence of potassium iodide; the product was then fixed on an anionic exchanger. The absorbance of the gel, packed in a 1 mm cell, is measured directly. PAR and KI concentrations were optimized simultaneously using response surface methodology (RSM) from sequential experimental Doehlert designs. The ...

  12. Determination of niobium in rocks by an isotope dilution spectrophotometric method

    Science.gov (United States)

    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.

  13. In situ Silver Spot Preparation and on-Plate Surface-Enhanced Raman Scattering Detection in Thin Layer Chromatography Separation

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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.

  14. Dual-Wavelength Spectral Correction Method for Simultaneous Determination of V(IV and V(V

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    R. Mirzajani

    2011-01-01

    Full Text Available Simultaneous determination of V(IV and V(V was performed when the calibration matrix was obtained using beta-corrected spectral data. The method is based on the reaction between V(IV and V(V and 4-(2-pyridylazo-resorcinol (PAR as a ligand at pH 6. Using β-correction technique true absorbance of chelate produced can be calculated because the quantity of absorbance, which has related to the fraction of reagent that reacted with metal ion and has been subtracted when reagent applied as reference by this correction has compensated. The parameters controlling behavior of the system were investigated and optimum conditions selected. Calibration model was constructed based on absorption spectra in the 540-600 nm range for 25 different mixtures of V(IV and V(V in the concentration ranges of 0.10-4.00 µgmL−1 of V(IV and 0.10-5.00 µgmL−1of V(V. Applying this method to the analysis of mixtures of V(IV and V(V in waste water and soil samples with total relative standard error of less than 4.3% validated the proposed method.

  15. On-line Determination of Zinc in Water and Biological Samples after Its Preconcentration onto Zincon Anchored Polyurethane Foam.

    Science.gov (United States)

    Azeem, Sami M Abdel; Hanafi, Hassan A; El-Shahat, M F

    2015-01-01

    A fast and sensitive on-line procedure for the determination of zinc in water and biological samples was developed. Zinc was preconcentrated in a mini-column packed with polyurethane foam (PUF) chemically modified with zincon via -N=N- bonding. The optimal conditions for preconcentration were pH 8.5 and sample flow rate of 4.0 mL min(-1). Quantitative desorption of Zn(II) was obtained by 0.1 mol L(-1) hydrochloric acid and subsequent spectrophotmetric determination using 4-(2-pyridylazo)-resorcinol at 498 nm. The obtained detection limit was found to be 3.0 ng mL(-1), precision (RSD) was 4.8 and 6.7% at 20 and 110 ng mL(-1), respectively, for 60 s preconcentration time and enrichment factor was 31. The linearity range was from 10 to 120 ng mL(-1) and maximum sample throughput was 20 h(-1). Finally, the method was successfully applied to the determination of zinc in tap water, Nile River water and human urine samples with RSD in the range of 1.1 - 8.3%.

  16. Chelation ion chromatography of alkaline earth and transition metals a using monolithic silica column with bonded N-hydroxyethyliminodiacetic acid functional groups.

    Science.gov (United States)

    McGillicuddy, Nicola; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Jones, Phil; Paull, Brett

    2013-02-08

    A commercially available porous silica monolithic column (Onyx Monolithic Si, 100 mm×4.6 mm I.D.) was 'in-column' covalently functionalised with 2-hydroxyethyliminodiacetic acid (HEIDA) groups, and applied to the simultaneous and rapid separation of alkaline earth and transition metal ions, using high-performance chelation ion chromatography (HPCIC). With a 0.3mM dipicolinic acid (DPA) containing eluent, the baseline separation of various common transition and heavy metal ions and the four alkaline earth metal ions could be achieved in under 14 min with a flow rate of just 0.8 mL/min. Detection was achieved using spectrophotometric detection at 540 nm after post-column reaction (PCR) with 4-(2-pyridylazo)-resorcinol (PAR). Significant effects from variation of eluent nature, concentration and temperature upon selectivity and retention were demonstrated with the new monolithic silica chelating phase. Under optimised conditions (0.165 M LiNO(3) eluent, pH 2.5), peak efficiencies of 54,000, 60,000 and 64,000 N/m, for Zn(2+), Mn(2+) and Cd(2+), respectively, were recorded, far exceeding that previously reported for IDA based chelation ion exchange columns.

  17. Sequential injection chromatography with post-column reaction/derivatization for the determination of transition metal cations in natural water samples.

    Science.gov (United States)

    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 ofwater samples was well suited for routine analysis with sub-micromolar limits of detection.

  18. A flow injection system for the spectrophotometric determination of lead after preconcentration by solid phase extraction onto Amberlite XAD-4

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    Jintana Klamtet

    2008-07-01

    Full Text Available An on-line flow injection analysis (FIA system for determination of lead (II in water samples with a preconcentration step and spectrophotometric detection was investigated. The system is based on preconcentration of lead (II on a column packed with Amberlite XAD-4 resin and detection by means of 4-(2-pyridylazoresorcinol (PAR–lead complex formation with maximum absorption at 523 nm. Chemical and FIA variables influencing performance of the system were optimised. Two linear calibration curves with a range of 0.01 - 0.40 and 0.40 – 0.80 mg L-1 were obtained. The developed system allowed a throughput rate of 16 samples h-1 with a 9-fold enrichment factor and a detection limit of 7 µg L-1. Relative standard deviation for 10 replicated injections of 0.25 mg L-1 was 2.3%. Recoveries of the method were in the range of 80-94 %. The procedure was validated by analysis of lead (II in real water samples, and the results were statistically compared with those obtained by flame atomic absorption spectrophotometry (FAAS. The results obtained both by the proposed method and by FAAS were in good agreement.

  19. FLOW INJECTION ON-LINE SEPARATION AND SPECTROPHOTOMETRIC DETERMINATION OF TRACES OF LEAD IN ENVIRONMENTAL SAMPLES%环境样品中痕量铅的流动注射在线分离及分光光度检测

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A flow injection method has been developed for the determination of lead in environmental samples by use of on-line preconcentration on a Pb*SpecTM column and spectrophotometric detection. The lead in sample solutions was adsorbed selectively on the column from 1mol*l-1 nitric acid and the retained lead was eluted with 0.1mol*l-1 ammonium oxalate.4-(2-pyridylazo)resorcinol (PAR) was used as a chromogenic reagent at pH 10 and the absorbance of Pb-PAR complex was monitored at 530 nm. The pumps, valves and spectrophotometer were controlled by a personal computer. The detection limit (3σ) was 3ng of lead. The RSD is 1.7% at a level of 0.4μg lead. The proposed method was successfully applied to the determination of lead in fly ash of an incinerator for industrial waste and in river water certified reference material provided by the Japan Society for Analytical Chemistry.

  20. Paired emitter-detector diode detection with dual wavelength monitoring for enhanced sensitivity to transition metals in ion chromatography with post-column reaction.

    Science.gov (United States)

    O' Toole, Martina; Barron, Leon; Shepherd, Roderick; Paull, Brett; Nesterenko, Pavel; Diamond, Dermot

    2009-01-01

    The combination of post-column derivatisation and visible detection are regularly employed in ion chromatography (IC) to detect poorly absorbing species. Although this mode is often highly sensitive, one disadvantage is the increase in repeating baseline artifacts associated with out-of-sync pumping systems. The work presented here will demonstrate the use of a second generation design paired emitter-detector diode (PEDD-II) detection mode offering enhanced sensitivity to transition metals in IC by markedly reducing this problem and also by improving signal noise. First generation designs demonstrated the use of a single integrated PEDD detector cell as a simple, small (15 x 5 mm), highly sensitive, low cost photometric detector for the detection of metals in IC. The basic principle of this detection mode lies in the employment of two linear light emitting diodes (LEDs), one operating in normal mode as a light source and the other in reverse bias serving as a light detector. The second generation PEDD-II design showed increased sensitivity for Mn(II)- and Co(II)-2-(pyridylazo)resorcinol (PAR) complexes as a result of two simultaneously acquiring detection cells--one analytical PEDD cell and one reference PEDD cell. Therefore, the PEDD-II employs two wavelengths whereby one monitors the analyte reaction product and the second monitors a wavelength close to the isosbestic point. The optimum LED wavelength to be used for the analytical cell was investigated to maximise peak response. The fabrication process for both the analytical and reference PEDD cells was validated by determining the reproducibility of detectors within a batch. The reproducibility and sensitivity of the PEDD-II detector was then investigated using signals obtained from both intra- and inter-day chromatograms.

  1. Membrane optode for mercury(II) determination in aqueous samples

    Energy Technology Data Exchange (ETDEWEB)

    Kalyan, Y. [Department of Environmental Sciences, S.V. University, Tirupati 517502 (India); Pandey, A.K.; Bhagat, P.R.; Acharya, R.; Natarajan, V. [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Naidu, G.R.K. [Department of Environmental Sciences, S.V. University, Tirupati 517502 (India); Reddy, A.V.R., E-mail: avreddy@barc.gov.in [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2009-07-15

    A color changeable optode for Hg(II) was prepared by the immobilization of a dye 4-(2-pyridylazo)resorcinol (PAR) and a liquid ion-exchanger trioctylmethylammonium chloride (Aliquat-336) in the tri-(2-ethylhexyl) phosphate plasticized cellulose triacetate matrix. Hg(II) and CH{sub 3}Hg{sup +} from aqueous samples could be quantitatively preconcentrated in this transparent optode producing a distinct color change ({lambda}{sub max} = 520 nm) within 5 min equilibration time in bicarbonate aqueous medium or 30 min in natural water. Whereas optode sample without Aliquat-336 did not change its color corresponding to Hg-PAR complex on equilibrium with the same aqueous solution containing Hg(II) ions. The uptake of Hg(II) was found to be pH dependant with a maximum (>90%) at a pH 7.5. The uptake of ions like Cu(II), Fe(II), Zn(II) and Pb(II) was negligible in the optode where as the uptake of Cd(II) and Zn(II) ions was 10-15% at pH 7.5. The optode developed in the present work was studied for its analytical application for Hg(II) in the aqueous samples by spectrophotometry, radiotracer ({sup 203}Hg), Energy Dispersive X-ray Fluorescence (EDXRF) analyses and Instrumental Neutron Activation Analysis (INAA). The minimum amount of Hg(II) required to produce detectable response by spectrophotometry, INAA and EDXRF were found to be 5.5, 1 and 12 {mu}g, respectively. This optode showed a linear increase in the absorbance at {lambda}{sub max} = 520 nm over a concentration range of 0.22-1.32 {mu}g/mL of Hg(II) ions in aqueous solution for 5 min. The preconcentration of Hg(II) from large volume of aqueous solution was used to extend the lower limit of concentration range that can be quantified by the spectrophotometry of optode. It was observed that preconcentration of 11 {mu}g Hg(II) in 100 mL (0.11 {mu}g/mL) in aqueous samples gives a distinct color change and absorbance above 3{sigma} of the blank absorbance. The optode developed in the present work was found to be reusable.

  2. A highly selective molecularly imprinted electrochemiluminescence sensor for ultra-trace beryllium detection

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianping, E-mail: likianping@263.net; Ma, Fei; Wei, Xiaoping; Fu, Cong; Pan, Hongcheng

    2015-04-29

    Graphical abstract: A novel molecular imprinted electrochemiluminescence sensor was fabricated for ultra-trace Be{sup 2+} detection with an extremely lower detection limit based on the luminol–H{sub 2}O{sub 2} ECL system. - Highlights: • A novel molecular imprinted electrochemiluminescence sensor was fabricated for ultra-trace Be{sup 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{sub 2}O{sub 2} ECL system, which was applied to detect Be{sup 2+}. • It gave an extremely lower detection limit (2.35 × 10{sup −11} mol L{sup −1}) than the reported methods. - Abstract: A new molecularly imprinted electrochemiluminescence (ECL) sensor was proposed for highly sensitive and selective determination of ultratrace Be{sup 2+} determination. The complex of Be{sup 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{sup 2+} concentration could then be determined indirectly. The results showed that in the range of 7 × 10{sup −11} mol L{sup −1} to 8.0 × 10{sup −9} mol L{sup −1}, the ECL intensity had a linear relationship with the Be{sup 2+} concentrations, with the limit of detection of 2.35 × 10{sup −11} mol L{sup −1}. This method was successfully used to detect Be{sup 2+} in real water samples.

  3. 基于指示剂置换法利用紫外-可见光谱和比色检测水溶液中的半胱氨酸%Detection of Cysteine in Aqueous Solution Based on Indicator Displacement by Ultraviolet-Visible and Colorimetric Methods

    Institute of Scientific and Technical Information of China (English)

    李咏玲; 张建刚; 卫艳丽; 程芳琴

    2012-01-01

    Through ultraviolet-visible( UV-Vis) spectra, a strategy for the determination of cysteine(Cys) was established by simply assembling copper( II ) and 4-(2-pyridylazo)-resorcinol( PAR) in a molar ratio of 1 : 1 in aqueous solution. Cys could be detected in 10 mmol/L4-(2-hydroxyethyl)-l-piperazineethanesulfonic acid (HEPES) buffer(pH = 7. 0) system containing copper( II )-PAR due to coordination competition. The Cu2+-PAR ensemble was highly selective for Cys without interference from other amino acids. From the UV-Vis ab-sorbance value changes of Cu2+-PAR and Cu2+-PAR-Cys, the optimal coordinated ratio of PAR : Cu2+ was found to be 1:1 and Cu2+:Cys was 1:3. It is worthy mentioned that within the concentration range of 0-240 μmol/L in aqueous solution, the measurement of Cys conformed well with linear law, with an average coefficient of light extinction of 7519 L/(mol·Cm) and a correlation coefficient of 0. 9982. The whole recognition process for Cys gave rise to a rapid visual color change from pink to yellow which can be observed simultaneously with naked eye.%基于半胱氨酸(Cys)与二价铜离子的配位作用,发展了一种在纯水溶液中以4-(2-吡啶偶氮)间苯二酚(PAR)为指示剂,通过紫外-可见光谱定性定量检测半胱氨酸的方法.研究发现,在pH=7.0的含有PAR和二价铜离子(摩尔比为1∶1)的缓冲溶液中,当加入半胱氨酸后,由于配位竞争使PAR释放出来,实现了对半胱氨酸的识别,选择性研究结果表明,其它氨基酸不干扰体系对半胱氨酸的测定.通过紫外-可见光谱(UV-Vis)对识别过程进行了研究,确定了Cu2+与PAR的配位比为1∶1,Cu2+与Cys的配位比为1∶3;半胱氨酸的线性关系变化范围为0 ~ 240 μmol/L,ε=7519 L/( mol·cm),线性相关系数为0.9982.在检测过程中可观察到溶液颜色由桃红色变成了黄色.