A simple, rapid and sensitive kinetic spectrophotometric method is proposed for the determination of trace amounts of silver ion in the concentration ranges of 2-20 and 20-50 μg L-1. The proposed method is based on the catalytic effect of Ag(I) on the oxidation reaction of new fuchsin by potassium peroxodisulfate in the presence of 1,10-phenantroline as an activator at pH:5.0. The reaction is followed spectrophotometrically by measuring the change in absorbance at 547 nm using the initial rate method during the indicator reaction of 5 minute. The reaction rate variables like pH, reagent and activator concentrations and effect of reaction time and temperature were optimized in order to achieve the maximum analytical sensitivity. The experimental and theoretical detection limits of the developed method were found as 0.475 μg L-1 and 1.50 μg L-1, respectively. The relative standard deviations for five replicate measurements of 15 and 35 μg L-1 of Ag(I) were 5.27% and 3.32%, respectively. The effect of different diverse ions on the determination of silver was studied and found to be free from most interference. The method was successfully applied to the determination of silver in photographic solutions and different real water samples such as tap water, pond water and natural spring waters.

A new cloud point extraction (CPE) method was developed for the separation and preconcentration of copper (II) prior to spectrophotometric analysis. For this purpose, 1-(2,4-dimethylphenyl) azonapthalen-2-ol (Sudan II) was used as a chelating agent and the solution pH was adjusted to 10.0 with borate buffer. Polyethylene glycol tert-octylphenyl ether (Triton X-114) was used as an extracting agent in the presence of sodium dodecylsulphate (SDS). After phase separation, based on the cloud point of the mixture, the surfactant-rich phase was diluted with acetone, and the enriched analyte was spectrophotometrically determined at 537 nm. The variables affecting CPE efficiency were optimized. The calibration curve was linear within the range 0.285-20 µg L-1 with a detection limit of 0.085 µg L-1. The method was successfully applied to the quantification of copper in different beverage samples.

A novel sensitive and relatively selective kinetic method is presented for the determination of V(V), based on its catalytic effect on the oxidation reaction of Ponceau Xylydine by potassium bromate in presence of 5-sulfosalicylic acid (SSA) as activator. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of Ponceau Xylydine at 640 nm between 0.5 to 7 min (the fixed time method) in H3PO4 medium at 25ºC. The effect of various parameters such as concentrations of H3PO4, SSA, bromate and Ponceau Xylydine, temperature and ionic strength on the rate of net reaction were studied. The method is free from most interferences, especially from large amounts of V(IV). The decrease in absorbance is proportional to the concentration of V(V) over the entire concentration range tested (1-15 ng mL−1) with a detection limit of 0.46 ng mL-1 (according to statistical 3Sblank/k criterion) and a coefficient of variation (CV) of 1.8% (for ten replicate measurement at 95% confidence level). The proposed method suffers few interferences such as Cr(VI) and Hg(II) ions. The method was successfully applied to the determination of V(V) in tap water, drinking water, bottled mineral water samples and a certified standard reference material such as SRM-1640 with satisfactory results. The vanadium contents of water samples were also determined by FAAS for a comparison. The recovery of spiked vanadium(V) was found to be quantitative and the reproducibility was satisfactory. It was observed that the results of the SRM 1640 were in good agreement with the certified value.