Determination of sulphur(II) compounds by flow injection analysis with application of the induced iodine/azide reaction

Sulphur(II) compounds that rapidly induce the iodine/azide reaction are determined by injection of 10-μl samples into an iodine/azide solution at a flow rate of 1.4 ml min^?1. Iodine consumption in the induced reaction is detected by biamperometry with platinum electrodes. The linear calibration ranges depend on the concentration of iodine in the iodine/azide solution pumped. The detection limit for thiosulphate, 2-mercapto-pyrimidine, 2-thiouracil, 2-thiobarbituric acid or 6-mercaptopurine is 0.1 mg l^?1 and for sulphide, cysteine, thiourea or glutathione is 0.2 mg l^?1 in the injected sample.