DETERMINATION OF ARSENIC, SELENIUM AND MERCURY IN AN ESTUARINE SEDIMENT STANDARD REFERENCE MATERIAL USING FLOW-INJECTION AND ATOMIC-ABSORPTION SPECTROMETRY

A Bow-injection analysis atomic absorption spectrometric (FIA-AAS) met hod was developed for the determination of trace amounts of arsenic, s elenium and mercury in a proposed estuarine sediment standard referenc e material (SRM 1646a). The samples were prepared in two manners: a) A wet digestion procedure with HNO3, H2SO4, and HClO4 using a reflux co lumn and b) A microwave-oven digestion procedure utilizing HNO3, H2SO4 , and HCl for As and Se, and HNO3 for Hg. Microwave-oven digestion pro vides results comparable to those found by reflux column digestion and reduces the sample preparation time by a factor of 10. The proposed m ethod employing the microwave-oven digestion procedure coupled with FI A-AAS for As and Se, and FIA-CVAAS for Hg, has detection limits of 0.1 5 ng As/ml, 0.17 ng Se/ml and 0.15 ng Hg/ml.