Kinetic-Spectrophotometric Determination of Tungsten(VI) Based on Azure I-Ti(III)Reaction in the Presence of Thiocyanate as an Activator

摘要

The catalytic effect of tungsten(VI)and activating effect of thiocyanate on the reduction reaction of Azure I by Ti(III)was used to develop a sensitive and rapid kinetic spectropho-tometric method for the determination of tungsten(VI).The reaction was monitored spectrophotometrically by measuring the change in absorbance(AA)at 646 nm using a fixed time method(2.5 min).The effect of different variables on the reaction was investigated and optimized in order to achieve the highest sensitivity.The calibration graph was linear in the range 5-90 ng mL~(-1)and the detection limit was 2.9 ng mL~(-1).The relative standard deviation for ten replicate measurements of 10 and 50 ng mL~(-1)of tungsten was 4.7 and 3.5,respectively.The method was successfully applied to the determination of tungsten in spring water samples.