by Assay
Magnesium Sulphate contains not less than 99.0 per cent and not more than 100.5 per cent of MgSO4, calculated on the dried basis. Weigh accurately about 0.3 g, dissolve in 50 ml of water, add 10 ml of strong ammonia-ammonium chloride solution and titrate with 0.05 M disodium edetate, using 0.1 g of mordant black II mixture as indicator, until a blue colour is obtained. 1 ml of 0.05 M disodium edetate is equivalent to 0.00602 g of MgSO4.
