Ultrasensitive determination and non-chromatographic speciation of inorganic arsenic in foods and water by photochemical vapor generation-ICPMS using CdS/MIL-100(Fe) as adsorbent and photocatalyst

The determination of inorganic arsenic species in real samples can be particularly challenging due to their trace levels and the interferences arising from sample matrix. Normally, the speciation analysis necessitates chromatographic separation. Herein, we report a novel method for the ultrasensitive detection and non-chromatographic speciation of inorganic arsenic by inductively coupled plasma mass spectrometry (ICP-MS), utilizing CdS/MIL-100(Fe) composites as an adsorbent and photocatalyst. The synthesized CdS/MIL-100(Fe) could completely adsorb As(V) and As(III) within 5 and 105 min, respectively. Following filtration and re-suspension in formic acid, the adsorbed As(III)/As(V) were reduced to arsine (AsH3) under UV irradiation and swept to ICP-MS for detection. The limits of detection were found to be 1.7 ng L-1 (without preconcentration) and 0.11 ng L-1 (after 20-fold preconcentration). The method was successfully applied to the determination of trace inorganic arsenic in various food and water samples.