2-(2-Thiazolylazo)-p-cresol as a spectrophotometric reagent for vanadium determination in the presence of ascorbic acid

Abstract

The present work describes the use of 2-(2-thiazolylazo)-p-cresol (TAC) as a spectrophotometric reagent for vanadium determination. TAC reacts with vanadium(IV) in the presence of ascorbic acid, forming a red complex with absorption maximum at 525 nm. The following parameters were studied: complex stability, pH effect, amount of TAC, amount of acetate buffer, HEDTA effect, order of addition of reagents and Beer's law validity. TAC can be used for vanadium determination in the pH range 4.6–6.0, with molar absorptivity of 2.11 × 104Lmole−1 cm−1 (at525nm). Beer's law is obeyed up to 2.0 μg mL−1. Many cation interferences can be easily eliminated by using HEDTA as a masking agent. Steel reference standards were used to test the proposed procedure and the accuracy and precision obtained were satisfactory.