Direct determination of ultratrace arsenic in blood samples using an in-situ dielectric barrier discharge trap coupled with atomic fluorescence spectrometry

Abstract

A novel direct sampling hydride generation (HG) system was utilized and is first reported to introduce a blood sample into a in-situ dielectric barrier discharge atomic fluorescence spectrometer (DBD-AFS) for ultratrace determination of arsenic based on the gas phase enrichment (GPE) principle. The in-situ DBD unit was fitted with three concentric quartz tubes to replace the conventional atomizer in the AFS. Followed by a simple disruption for 2 minutes and centrifugation for 8 minutes of the blood sample in 3% HNO3 (v:v) extractant, the arsenic extraction and protein precipitation can be achieved up to 40 multiple dilutions. A supernatant consisting of 5% HCl (v:v) and 5 g/L KBH4 in 1.5 g/L KOH was introduced into the HG-in-situ DBD-AFS. Then, arsenic generating from the HG was trapped using 11 kV DBD at 110 mL/min air, swept for 190 seconds at 500 mL/min Ar, and released with 13 kV at 180 mL/min H2. Under the optimal conditions, the linear regression coefficient (R2) was 0.996 ranging from 0.05 to 300 µg/L. The method detection limit (LOD) obtained was 7 pg arsenic, with a 3.9% precision using 11 repeated measurements for real blood samples. The spiked recoveries for the real blood samples were 96-107%. Furthermore, it was found that the arsenic concentrations measured by the proposed method were not significantly different (P > 0.05) from using microwave digestion in ICP-MS. The complete analysis, including sample pre-treatment, was performed within 15 minutes. The results show that the proposed method offers a fast and reliable analysis of ultratrace levels of arsenic in real blood samples.