Analytical Sciences

Arsenic Determination in Marine Sediment Using Ultrasound for Sample Preparation

Fabrina R. S. BENTLIN,* Fábio A. DUARTE,** Valderi L. DRESSLER,** and Dirce POZEBON*

*Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, 91501-970, Porto Alegre, RS, Brasil
**Departamento de Química, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brasil

This work deals with As determination in marine sediment using ultrasound for sample preparation. It is shown that As can be quantitatively extracted from marine sediment using 20% (v/v) HCl and sonication. The slurry is centrifuged and the analyte is determined in the supernatant by hydride generation atomic absorption spectrometry (HG AAS). A flow injection (FI) system is employed for hydride generation, with 0.5% (m/v) NaBH₄ used as reducdant and a 20% (v/v) HCl used as sample carrier. The limit of quantification is 1.6 µg g^-1 of As, which is based on 800 µl of sample solution and 0.200 g of sample mass in a volume of 50 mL. Certified and non certified marine sediment samples were analyzed; the results were in accordance with the certified or reference values. Speciation analysis by HPLC-ICP-MS showed that As(V) is the only detectable As species present in the supernatant of the centrifuged sample.

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