Determination of Ten Organoarsenic Compounds Using Microbore High-performance Liquid Chromatography Coupled With Electrospray Mass Spectrometry–Mass Spectrometry

Abstract

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 µg l ^-1 level.