Abstract
Sulphate (0–80 μg) is reduced by heating with a mixture of hydriodic acid, formic acid and red phosphorus, the gas is swept by nitrogen into 1 M sodium hydroxide and sulphide is quantified by differential pulse polarography from the peak at –0.76 V vs. Ag/AgCl. None of the ions investigated interfered except those capable of reduction to hydrogen sulphide.