SPE speciation of inorganic arsenic in rice followed by hydride-generation atomic fluorescence spectrometric quantification

Due to high toxicity, inorganic arsenic (iAs) species are the focus of monitoring effort worldwide. In this work arsenic was first extracted from rice by microwave-assisted digestion in HNO3–H2O2, during which AsIII was oxidized to AsV. Silica-based strong anion exchange cartridges were used to separate AsV from organic forms. After prereduction by iodide, iAs was quantified by hydride-generation atomic fluorescence spectrometry (HG-AFS). This method achieved 1.3 ng g−1 limit of detection (LOD), and 94±3% and 93±5% recoveries, respectively, for AsIII and AsV at 100 ng g−1. Validation was performed using standard reference material NIST 1568a (102 ng g−1) and ERM BC211 (124 ng g−1) rice flour. By eliminating chromatography, SPE speciation gained throughput and cost advantages. HG-AFS, at 10% budget and operation cost of a typical inductively-couple plasma mass spectrometer (ICPMS), proved highly sensitive and specific for iAs quantification.