Rapid screening of arsenic species in urine from exposed human by inductively coupled plasma mass spectrometry with germanium as internal standard

In the present work, internal standardization based on species-unspecific isotope dilution analysis technique is proposed in order to overcome the matrix effects and signal drift originated in the speciation of As in urine by HPLC-ICP-MS. To this end, 72Ge has been selected as a pseudo-isotope of As. The resulting mass flow chromatogram of the element allows the calculation of the corrected overall species concentrations without requiring any methodological calibration, providing high-throughput sample processing. The validation was carried out by analyzing a blank human urine fortified at three concentration levels and an unspiked human urine sample containing different species of arsenic. In all cases, recoveries ranging from 90 to 115% and RSD below 10% were attained with this approach. Furthermore, the proposed method provided results in excellent agreement with those obtained using standard additions and internal standard calibration, allowing a fast way to assess human exposure to arsenic species.