Sensitive Kinetic-Spectrophotometric Determination of Iodate in Iodized Table Salt Based on Its Accelerating Effect on the Reaction of Bromate with Chloride Ion in the Presence of Hydrazine (original) (raw)
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Acta Chimica Slovenica, 2008
A very sensitive and selective kinetic catalytic spectrophotometric method has been developed for the determination of Cu (II). The method is based on the catalytic effect of Cu (II) on the reaction of sulfanilic acid with hydrogen peroxide at pH 6 and 25 °C in aqueous solution. The increase in the absorbance of the reaction mixture at 330nm at a fixed time is proportional to the concentration of Cu (II) over the range of 0.05-6 µg ml -1 . Partial least squares modeling as a powerful multivariate statistical tool is also applied and compared for determination of Cu(II) in aqueous solution. The experimental matrix for partial least squares calibration (PLS) method was designed with 14 samples. The cross-validation method was used for selecting the number of factors. The root mean squares error prediction (RMSEP) and the relative error prediction REP(%) were 0.11 and 3.78% respectively. The effects of various cations and anions on Cu (II) determination have been investigated. The capability of the method for the analysis of real sample was evaluated by determination of Cu (II) in serum samples of persons with Wilson disease.
A very sensitive and selective kinetic catalytic spectrophotometric method has been developed for the determination of Cu (II). The method is based on the catalytic effect of Cu (II) on the reaction of sulfanilic acid with hydrogen peroxide at pH 6 and 25 °C in aqueous solution. The increase in the absorbance of the reaction mixture at 330nm at a fixed time is proportional to the concentration of Cu (II) over the range of 0.05-6 µg ml -1 . Partial least squares modeling as a powerful multivariate statistical tool is also applied and compared for determination of Cu(II) in aqueous solution. The experimental matrix for partial least squares calibration (PLS) method was designed with 14 samples. The cross-validation method was used for selecting the number of factors. The root mean squares error prediction (RMSEP) and the relative error prediction REP(%) were 0.11 and 3.78% respectively. The effects of various cations and anions on Cu (II) determination have been investigated. The capability of the method for the analysis of real sample was evaluated by determination of Cu (II) in serum samples of persons with Wilson disease.
2013
Trace amount of Copper(II) has determined by spectrophotometric technique using 1-(2-pyridylazo)- 2-naphthal (PAN), as a new spectrophotometric reagent which is insoluble in water. PAN reacts in highly acidic solution at pH 2.40 to 2.50 with Cu(II) to give a pink chelate which has an absorption maximum (λmax.) at 550nm. The reaction is instantaneous and absorbance remains stable for over 48hrs. The average molar absorption co- efficient (e) was found to be 2.05×10 4 L mol -1 cm -1 and Sandell sensitivity is 3.23×10 −4 μg cm −2 . Linear calibration graphs were obtained for 0.1-4.0 μgL -1 of Cu(II) and RSD (%) is 1.16. The stoichiometric composition of the chelate is 1:2 (Cu:PAN). Large excess of over 50 cations, anions, and some common complexing agents (e.g. oxalate, phosphate, tartarate, thio-urea) do not interfere in the determination. The method was successfully used in the determination of Cu(II) in Several Standard Reference Materials as well as in some environmental and indust...
Central European Journal of Chemistry, 2009
A partial least squares (PLS-1) calibration model based on kinetic--spectrophotometric measurement, for the simultaneous determination of Cu(II), Ni(II) and Co(II) ions is described. The method was based on the difference in the rate of the reaction between Co(II), Ni(II) and Cu(II) ions with 1-(2-pyridylazo)2-naphthol in a pH 5.8 buffer solution and in micellar media at 25 o C. The absorption kinetic profiles of the solutions were monitored by measuring the absorbance at 570 nm at 2 s intervals during the time range of 0 -10 min after initiation of the reaction. The experimental calibration matrix for the partial least squares (PLS-1) model was designed with 30 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range 0.1-2 µg mL -1 for each cation. The proposed method was successfully applied to the simultaneous determination of Cu(II), Ni(II) and Co(II) ions in water and in synthetic alloy samples.
Analytical and Bioanalytical Chemistry, 2014
The ability of human serum albumin to capture unbound copper under different clinical conditions is an important variable potentially affecting homeostasis of this element. Here, we propose a simple procedure based on sizeexclusion chromatography with on-line UV and nitrogen microwave-plasma atomic-emission spectrometry (MP-AES) for quantitative evaluation of Cu(II) binding to HSA upon its glycation in vitro. The Cu-to-protein molar ratio for nonglycated albumin was 0.98±0.09; for HSA modified with glyoxal (GO), methylglyoxal (MGO), oxoacetic acid (GA), and glucose (Glc), the ratios were 1.30±0.22, 0.72±0.14, 0.50 ±0.06, and 0.95±0.12, respectively. The results were confirmed by using ICP-MS as an alternative detection system. A reduced ability of glycated protein to coordinate Cu(II) was associated with alteration of the N-terminal metal-binding site during incubation with MGO and GA. In contrast, glycation with GO seemed to generate new binding sites as a result of tertiary structural changes in HSA. Capillary reversed-phase liquid chromatography with electrospray-ionization quadrupole-time-of-flight tandem mass spectrometry enabled detection and identification of Cu(II) coordinated to the Nterminal metal-binding site (Cu(II)-DAHK) in all tryptic digests analyzed. This is the first report confirming Cu(II)-DAHK species in HSA by means of high-resolution tandem mass spectrometry, and the first report on the use of MP-AES in combination with chromatographic separation.
Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2011
A simple and selective spectrophotometric method was developed for the determination of copper(II) with 1-(2 ,4 -dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2 ,4 -dinitro APTPT] as a chromogenic reagent. The procedure was based on the synergistic extraction of copper(II) with 2 ,4 -dinitro APTPT in the presence of 0.5 mol L −1 pyridine to give green colored ternary complex of a molar ratio 1:2:2 (M:L:Py) in the pH range 8.7-10.5. It exhibits a maximum absorption of colored complex at 445 nm and 645 nm in chloroform against the reagent blank. Beer's law was followed in the concentration range 10-80 g mL −1 of copper(II) and optimum range of 20-70 g mL −1 the metal as evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of copper(II)-2 ,4 -dinitro APTPT-pyridine complex in chloroform are 0.87 × 10 3 L mol −1 cm −1 and 0.072 g cm −2 , respectively. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The proposed method is rapid, reproducible and successfully applied for the determination of copper(II) in binary and synthetic mixtures, alloys, pharmaceutical formulations, environmental and fertilizer samples. Comparison of the results with those obtained using an atomic absorption spectrophotometer also tested the validity of the method.
Copper(II) Determination by Immobilized Urease Inhibition in a Spectrometric Flow-Injection System
Biotechnology & Biotechnological Equipment, 2005
A flow-injection system for analysis of urea and copper(II) ions based on the immobilized urease onto seven modified acrylonitrile copolymer membranes was studied. The most suitable ones for the both flow-injection analysis were selected. The urease systems with membranes modified with NaOH+2-dimethylaminoethyl methacrylate (DMAEM), NaOH+DMAEM+ethylene diamine (EDA) provided higher urea sensitivity and precision of the measurements (R=0.99 and RSD about 3%). The calibration curves for copper (II) ions show that the systems with urease immobilized on membrane modified with NaOH+EDA and hydrazinium sulfate (NH 2 NH 2 .H 2 SO 4) had the highest sensitivity to Cu(II). The detection limit of Cu(II) for these systems was 0.1 mg l-1. The correlation coefficient of the linear intervals (R=0.99) and standard deviation (about 4.5 %), which guarantees good reproductivity of the copper analysis. The operational stability of the flow system with membrane modified with NaOH+EDA for analysis of Cu(II) was studied. The investigated immobilized system reached 50% inhibition after 25 days. The stability of immobilized urease membrane during storage was determined. The FIA sensitivity was found to remain almost the same for 40 days. The inhibition effect caused by a mixture of Cu(II), Zn(II) and Ni(II) ions in model solution and real water was also determined.
Sector-125, NOIDA-201303, INDIA @amity. I. Introduction Thiosemicarbazones have been used for spectrophotometric determination of various metal ions like iron[1], palladium[2], cobalt[3], Vanadium[4] etc. Cu(II) has been individually determined by complexing agents like Oxime[5-8] along with other thiosemicarbazones[9]. Similarly Ni(II) also has been determined individually using oximes[10]. Determination of both Cu(II) and Ni(II) has been done using biladiene[11], thiosemicarbazones[12], 5-methyl-2-furaldehyde thiosemicarbazone[13], isatin-p-thiosemicarbazone[14], substituted salicylaldehyde thiosemicarbazone[15], semicarbazone and thiosemicarbazone of 2-hydroxy-4ethoxy acetophenone[16], oxime[17] etc.
Talanta, 1994
A catalyttc spectrophotometnc method IS presented for the determmatlon of Cu(II), based on the oxtdatton of the leucocompound of the 2,6-drchlorophenohndophenol (DCPI),, m the presence of hydrogen peroxlde and the catalyttc effect of Cu(I1) on thts reactlon m ammoma-ammomum chlortde buffer solutton of pH 10 5 The above reactlon IS followed spectrophotometncally at 562 nm The study was carned out with a filter spectrophotometer equipped with a fiber optic and an Immersed type optlcal cell of 1 cm The opttmum operatmg condlttons regarding concentration of the reagents mvolved. pH and temperature were estabhshed The Interference effect of several metalhc species was also mvestlgated It was found that the proposed method shows fairly good selectlvlty and sensltlvtty. slmphclty and rapldtty compared to other kmettc methods me workmg curve of the recommended reactlon-rate method IS hnear m the concentratton range 5-300 ng/ml The relative standard devlatlon for a standard solution of 30 ngjml Cu(I1) 1s better than 2 5% The method was apphed successfully on the determination of Cu(I1) m a wade vanety of real samples such as alloys, pharmaceuticals, foodstuffs and envlronmental samples The results were compared to those received wtth offictal methods Good agreement was attamed