Determination of arsenic in sea water,marine plants and silicate and carbonate sediments

Cocrystallization with thionalide in a 0.05 N sulphuric acid medium is proposed for the recovery of microgram amounts of arsenic from sea water and from solutions prepared by the decomposition of silicates and marino plants. After destruction of the organic precipitant, arsenic is determined photomotrically by means of a single-solution molybdenum blue method. The overall recovery for the whole process is 97-98%. Arsenic was determined in sea water with a coefficient of variation of 1.3% at a level of 2 μg As/l. Coefficients of variation of 2.6% and 1.7% were found, for the determination of the element in marine sediments and plants at levels of 6.6 μg/g and 1.7 μg/g respectively. The U. S. Geological survey standard granite G 1 was found to contain 1.2 μg As/g