SLURRY SAMPLING HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY FORTHE DETERMINATION OF EXTRACTABLE SOLUBLE AS IN SEDIMENT SAMPLES/

A method combining the sampling of slurry pretreated by ultrasonic agi tation and microwave assisted extraction with hydride generation atomi c absorption spectrometry (HGAAS) for the determination of arsenic in sediment samples is proposed and evaluated. The pretreatment of slurri ed samples by ultrasonication enabled the extraction of (approximately ) up to 85% of arsenic from the studied sediment samples. The further (slight) improvement of the efficiency of extraction was accomplished by the introduction of a short microwave-accelerated treatment. L-cyst eine was used as an efficient pre-reduction reagent. The accuracy and precision of the slurry sampling HGAAS method were studied using the c ertified reference materials: Sediment GBW 30043 (NRCCRM, People's Rep ublic of China), Sediment NIST 2704 (NIST, USA) and Marine Sediment BC SS-1 (NRCC, Canada). The relative standard deviation of the full (over all) analytical procedure was 8.5% and an absolute limit of detection of 2.75 ng was achieved. Factors which influence the reliability of th is method are, for example, the choice of slurry liquid phase (extract ion medium), sample homogeneity and, in particular, very effective mix ing of slurries. (C) 1998 Elsevier Science B.V.