SPECTROPHOTOMETRIC DETERMINATIONS OF TRACE AMOUNTS VANADIUM(V) USING SAFRANINE O AND FUCHSINE AS NEW REAGENTS

摘要

Two facile, sensitive, indirect spectrophotometric methods are developed for the determination of trace amounts of vanadium(V) using safranine O and fuchsine as new reagents. Both methods are based on the liberation of iodine by the reaction of vanadium(V) with potassium iodide in acid medium. The liberated iodine bleaches the red colour of the safranine O and the magenta red colour of the fuchsine, respectively. The methods involve the formation of a brownish-red complex of V(V) with safranine O having an absorption maximum at lambda(max) 530 nm as well as the formation of a cherry-red complex of V(V) with fuchsine having an absorption maximum at lambda(max) 510 nm. The optimum conditions for the determination are established. The Beer law is applicable in the range of 0.05-12.4 mg l(-1) usingsafranine O and 0.5-12.0 mg l(-1) using fuchsine as reagents. The methods detection limit, limit of quantification and molar absorptivity are reported as follows: for vanadium(V) safranine O system are found to be 0.635 mu g ml(-1), 1.920 mu g ml(-1), 3.06 x 10(4) l mol(-1)cm(-1). Respectively for vanadium(V)-fuchsine system the same data are found to be 0.119 mu g ml(-1), 0.362 mu g ml(-1), 4.2 x 10(4) l mol(-1)cm(-1). The methods are free from common interferences and were successfully applied for the determination of vanadium(V) in alloys, synthetic samples, water samples and soils.