Selective determination of As(III) and total inorganic arsenic in rice sample using in-situ μ-sorbent formation solid phase extraction and FI-HG AAS

Abstract

A noteworthy solid phase extraction procedure was developed for speciation of inorganic arsenic in rice samples using flow injection-hydride generation atomic absorption spectrometry (FI-HG AAS). The procedure is based on the in-situ formation of quaternary ammonium salt as μ-sorbent. A small amount of tetra-n-butylammonium bromide (TBAB) was used as phase-transfer agent and injected into the sample solution. After shaking, a small volume of perchlorate was added as ion-pairing agent. Due the interaction between these agents, fine particle solids are formed. As(III) was selectively extracted after complexation with ammonium pyrrolidinedithiocarbamate (APDC). The suspension was centrifuged and the sedimented phase can be leached with HCl and introduced into the FI-HG AAS to recover the adsorbed analyte. The advantages of this procedure include short extraction time, good dispersion, good recovery and low residue formation. The variables were optimized by fractional factorial design and response surface methodology. The LOD and LOQ were, respectively, 0.01 and 0.04 μg g−1. The procedure shows potential for determination of low concentrations of As(III), with pre-concentration factor 17 and RSD of 5.5 %. The method was applied on IRMM-804 Rice Flour and no significant difference (p>0.05) was observed, it can be successfully applied to the monitoring of arsenic in real samples.