A novel method for multi-matrix arsenic speciation analysis by anion-exchange HPLC-ICP-MS in the framework of the third (French) total diet study

This study presents the development and validation of a precise analytical method for the speciation analysis of arsenic (As) compounds, including inorganic species [As(III) and As(V)] and organic species such as monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The method employs anion-exchange high-performance liquid chromatography (AE HPLC) coupled with inductively coupled plasma–mass spectrometry (ICP-MS). To optimize the sample preparation process, microwave-assisted extraction (MAE) and heat-assisted extraction (HAE) techniques were evaluated and compared. Separation of all four arsenic species was achieved with baseline resolution within 10 min, utilizing an anion-exchange column and a mobile phase gradient of 0.5 and 5 mM ammonium carbonate with 3% (v/v) methanol at a pH of 9.3. The method validation followed the accuracy profile approach, employing six different food matrices analyzed in duplicate over six separate days within a 6-week period. The method demonstrated good intermediate reproducibility, with coefficients of variation (CVR) ranging from 4.7% to 5.5%, while the bias was < 3%. The limit of quantification (LOQ) for the four species was 6.25 μg/kg (dry weight, dw), and the limit of detection (LOD) was 1.88 µg/kg (dw). These results confirm the robustness, accuracy, and suitability of the method for routine As speciation analysis across a variety of food matrices. The method is specifically intended to be applied to the analysis of a panel of food samples as part of the ongoing (French) third total diet study.