Determination of arsenic(III) and selenium(IV) using an on-line anodic stripping voltammetry flow cell with detection by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry.

An on-line anodic stripping voltammetry (ASV) flow system, interfaced with inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICPMS) detectors, has been used for determination of arsenic(III) and selenium(IV) and for elimination of polyatomic interferences which arise from chloride in sample matrices. Details of the working electrode preparation are discussed. Arsenic signals in ICP-AES were enhanced by as much as 10 times through preconcentration of sample volumes up to 5 mL. Using ICP-AES detection, recoveries for analyte spikes in 1:10 diluted urine were 102% for As(III) (matrix-matched standards) and 91% for Se(IV) (standards in electrolyte). Using ICPMS detection, determination of certified Se(IV) and Se(IV) spikes in diluted NIST SRM 2670 elevated urine gave recoveries of 92-103%, while recoveries of As(III) spikes in diluted NIST SRM 2670 urine ranged from 94 to 113%. High levels of chloride matrix exhibited little effect on the arsenic signal with ICP-AES or ICPMS detection. Elimination of the polyatomic interference ArCl+ in ICPMS was very efficient for diluted NIST SRM 2670 urine and for a synthetic matrix of 1000 micrograms/mL chloride.