Kinetic Spectrophotometric Determination of Trace Amounts of Thiocyanate Based on its Catalytic Effect on the Bromate- Crystal Violet Reaction in Biological Samples

A new analytical method was developed for determination of the thiocyanate content of spiked water and biological samples. This method is based upon the catalytic effect of the ion on the reaction between sodium bromate and crystal violet (CV) in acidic media. The decolourisation of CV was used in order to monitor the reaction spectrophotometrically at 630 nm. The variables affecting the reaction rate were determined and optimized. The method is simple, rapid, relatively sensitive and precise. The limit of detection (3σ) was 6 ng mL -1 and the calibration range was linear over the thiocyanate concentration range of 10-1250 ng mL -1 . The relative standard deviations for ten replicate determinations of 0.250, 0.500 and 1.00 µg mL -1 were 4.36%, 3.04% and 1.11%, respectively. Influences of the potentially interfering substances were also studied. The method was successfully used to determine the thiocyanate content of spiked water and biological samples.