Abstract

A novel hydride generation atomic absorption spectrometric method is developed for speciation analysis of inorganic arsenic in flours. This method is based on the leaching of arsenic from sample slurry through the sonication followed by hydride generation in the slurry and determination of the corresponding hydrides. The content of arsenic (III) [As(III)] was determined under 1% HCl acidity condition using both inhibitory effect of 8-Hydroxyquinoline (8-HQ) on arsenic(V) [As(V)] and its enhancing effect on As(III). The content of total inorganic arsenic was determined under 5% HCl acidity condition using enhancing effect of 8-HQ on both As(III) and As(V). The method detection limit was 4.0 μg kg^–1 for As(III) and 4.5 μg kg^–1 for total inorganic arsenic. The recovery ranging from 94.3 to 107% were found for As(III) and values from 98.5 to 104% for total inorganic arsenic. The relative standard deviations (RSDs) were in the range of 4.3–4.6% and 2.2–3.3% for the determination of As(III) and total inorganic arsenic, respectively. This method was validated by using the Chinese standard method (GB/T 5009.11-2003), with good agreement for total inorganic arsenic content in real samples. The developed method was successfully applied to speciation analysis of inorganic arsenic in wheat flour and rice flour with satisfactory results.

Key words: Slurry sampling, hydride generation, atomic absorption spectrometry, inorganic arsenic, speciation, flours.