A Spectrophotometric Flow Injection Method for Determination of Ultratrace Amounts of Phenylhydrazine by Its Inhibition Effect on the Reaction of Thionin and Nitrite

A simple flow injection colorimetric procedure for determining phenylhydrazine was established. It is based on the reaction of phenylhydrazine in sulfuric acid with thionin and sodium nitrite. Reaction was monitored spectrophotometrically by measuring thionin absorbance at λmax=602 nm. A standard or sample solution was injected into the sulfuric acid stream, which was then merged with sodium nitrite stream and thionin stream. Optimum conditions for determining phenylhydrazine were investigated by univariate method. Under the optimum conditions, a linear calibration graph was obtained over the range 0.05–0.60 μmol L−1, and the detection limit was 0.027 μmol L−1(s/n=3). The proposed method has been satisfactorily applied to the determination of phenylhydrazine in human serum and water samples

The Development of a New Kinetic Spectrophotometric Method for the Determination of Vanadium(V) Based on its Catalytic Effect on the Oxidation of Malachite Green Oxalate by Bromate in Acidic and Micellar Medium

A new, simple, sensitive and selective kinetic spectrophotometric method was developed for the determination of ultra trace amounts of vanadium(V). The method is based on the catalytic effect of vanadium(V) on the oxidation of malachite green oxalate (MG) by bromate in acidic and micellar medium. The reaction was monitored spectrophotometrically by measuring the decrease in the absorbance of malachite green oxalate (MG) at 625 nm with a fixed-time method. The decrease in the absorbance of MG is proportional to the concentration of vanadium(V) in the range of 1-100 ng/mL with a fixed time of 0.5-2 min from the initiation of the reaction. The limit of detection is 0.71 ng/mL of vanadium(V). The relative standard deviation for the determination of 5, 30, 50 ng/mL of vanadium(V) was2.5% 2.6%, 2.4% and respectively. The method was applied to the determination of vanadium(V) in water samples

Spectrophotometric determination of trace amounts of tellurium based on its catalytic effect in the reduction of gallocyanine with sodium sulphide

1871-1873A simple and sensitive kinetic spectrophotometric method for the determination of ultra trace amounts of tellurium(IV) has been proposed. It is based on the catalytic effect of Te(IV) on the reduction of gallocyanine by sodium sulphide. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of the reaction mixture at 618 nm. The method allows the determination of tellurium concentration in the range 2.0-200 ng/ml, with the detection limit of 1 ng/ml. The relative standard deviation for ten replicate determinations of 20.0 and 50.0 ng/ml Te( IV) is 1.7% and 1.1 %, respectively. The method has been applied to determination of tellurium in water samples

Fabrication and characterization of Cu(OH)₂/CuO nanowires as a novel sensitivity enhancer of the luminol–H₂O₂chemiluminescence system: determination of cysteine in human plasma

Cu(OH)2/CuO nanowires as a sensitivity enhancer in luminol–H2O2chemiluminescence system and its application for the determination of cysteine.</p