Speciation of Arsenic in Rice by High-Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

ABSTRACT

This study reports the optimization and validation of arsenic speciation of rice. Total arsenic was determined by inductively coupled plasma mass spectrometry; arsenite, arsenate, monomethylarsonic acid, and dimethyarsinic acid were quantified by high-performance liquid chromatography–inductively coupled plasma mass spectrometry. Methods using nitric acid and malonic acid were validated at various extraction conditions and mobile phase systems. The linear dynamic range, limit of detection, precision, fortification, and analysis of a white rice flour certified reference material (CRM-7503-a) were evaluated for quality assurance. The use of 5 mM malonic acid for extraction with an isocratic mobile phase was optimized for extraction time and temperature and employed for arsenic speciation in rice. The concentrations of total arsenic, arsenite, arsenate, monomethylarsonic acid, and dimethyarsinic acid were low compared to the provisional tolerable weekly intakes specified by the Food and Agriculture Organization/World Health Organization Joint Expert Committee on food additives and European food safety authority and thus do not pose a threat to consumers.

KEYWORDS:

• Arsenic speciation
• high-performance liquid chromatography–inductively coupled plasma mass spectrometry
• malonic acid
• rice