Determination of ten organoarsenic compounds using microbore high-performance liquid chromatography coupled with electrospray mass spectrometry mass spectrometry

An analytical method based on reversed-phase microbore HPLC coupled on-line with electrospray mass spectrometry (ES-MS) is described, The method allows for the determination of up to ten organoarsenicals in a single chromatographic run. Excellent sensitivity and selectivity is achieved by operating the triple quadrupole mass spectrometer in the selected-reaction monitoring mode, This is possible because the ions produced by collision-induced dissociation of the protonated molecules or molecular ions of the ten organoarsenicals are characteristic of each compound, The best LODs, achieved in the positive-ion mode, were between 2 and 21 pg of arsenic and corresponded to arsenicals which exist as cations in acidic solutions, The selectivity achieved by using this method allows for successful determination of arsenicals co-eluting during HPLC, This is a major improvement over other hyphenated techniques already used for arsenic speciation, e.g., HPLC-ICP-MS. Furthermore, the method was used for the analysis of an undiluted urine SRM in which arsenobetaine was determined to be present at the low mu g l(-1) level.