Determination of arsenic in biological samples by slurry sampling hydride generation atomic fluorescence spectrometry using in situ dielectric barrier discharge trap

Abstract

In this study, the slurry sampling hydride generation (SLS-HG) system was first coupled with in situ dielectric barrier discharge atomic fluorescence spectrometry (DBD-AFS) for arsenic analysis in biological samples based on the gas phase enrichment (GPE) principle. After a simple slurry dilution with 5% HCl (v/v) for microbiological and hair samples, the as-prepared slurry was introduced into the SLS-HG unit for arsine generation under 8 g L⁻¹ KBH₄ in 1.5 g L⁻¹ KOH. Here, the in situ DBD apparatus, comprising of the three-concentric quartz tubes, was employed to pre-concentrate arsenic to enhance the analytical sensitivity of the HG-AFS, as well as to eliminate interferences due to the dilution effect and matrix separation. This was followed by trapping with 11 kV at 110 mL min⁻¹ of air carrier gas, and 190 s Ar gas sweeping, arsenic was released with 13 kV at 180 mL min⁻¹ H₂ to the AFS for measurement. Under optimal conditions, 8 pg or 14 pg detection limits (2 mL sampling) for the microbiological or hair samples were achieved without extra pre-concentration, respectively. The linearity R² was 0.996 ranging from 0.05 μg L⁻¹ to 300 μg L⁻¹. The spiked recoveries for the real paramecium and micro diatom samples were 93–102%, and the measurements were in accordance with the certified reference material (CRM) values. The proposed SLS-HG-in situ DBD-AFS method is extremely suitable for ultratrace arsenic determination in biological samples to protect human health and environmental safety.