Catalytic and kinetic spectrophotometric method for determination of vanadium(V) by 2,3,4-trihydroxyacetophenonephenylhydrazone

A new catalytic and kinetic spectrophotometric method for the determination of vanadium(V) was studied using 2,3,4-trihydroxyacetophenonephenylhydrazone (THAPPH) as an analytical reagent. The present method was developed on the catalytic effect of vanadium on oxidation of THAPPH by hydrogen peroxide in hydrochloric acid-potassium chloride buffer (pH = 2.8) at the 20th minute. The metal ion has formed 1: 2 (M: L) complex with THAPPH. Beer's law was obeyed in the range 20-120 ng/mL of V(V) at lambda(max) 390 nm. The sensitivity of the method was calculated in terms of molar absorptivity (1.999 x 10(5) L mol(-1) cm(-1)) and Sandell's sensitivity (0.000254 mu g cm(-2)), shows that this method is more sensitive. The standard deviation (0.0022), relative standard deviation (0.56%), confidence limit (+/- 0.0015) and standard error (0.0007) revealed that the developed method has more precision and accuracy. The stability constant was calculated with the help of Asmu's (9.411 x 10(-11)) and Edmond's & Birnbaum's (9.504 x 10(-11)) methods at room temperature. The interfering effect of various cations and anions was also studied. The present method was successfully applied for the determination of vanadium(V) in environmental and alloy samples. The method's validity was checked by comparing the results obtained with atomic-absorption spectrophotometry and also by evaluation of results using F-test. (C) 2011 Production and hosting by Elsevier B.V. on behalf of King Saud University.