Determination of trace elements in sea water by graphite-furnace atomic absorption spectrometry after preconcentration by tetrahydroborate reductive precipitation

A method is described for the preconcentration of 16 elements from coastal and deep ocean sea water based on their reductive precipitation by sodium tetrahydroborate. The enrichment factors obtained were sufficient to permit the analysis of a near-shore sea-water reference material (11 elements) and an open ocean sea-water reference material (9 elements). Recoveries from 900 ml of sea water ranged from 80 to 107% (100-ml sample for Mn) with absolute blanks between <1.0 ng (Se) and 20 ng (Cu). Estimated detection limits varied from 0.3 ng l ^?1 (Pb) to 19 ng l^?1 (As) based on a 36-fold concentration of a 900-ml sample.