Multidimensional liquid chromatography with parallel ICP MS and electrospray MS/MS detection as a tool for the characterization of arsenic species in algae

Abstract.

An analytical strategy was developed for the characterization of arsenic species in a Laminaria algae. The approach was based on multidimensional liquid chromatography (LC) including sample extract cleanup by size-exclusion LC, separation of arsenic species by anion-exchange LC, verification of the chromatographic purity of arsenic-containing fractions, and their further purification, if necessary, by reversed-phase (RP) HPLC. The complementarity of ICP MS, used as the chromatographic detector, and ES MS/MS, employed for the identification of the peaks observed, was demonstrated. The species found were: arsenosugar A 11.7±0.5 µg g^–1, As^V 10.9±2.1 µg g^–1, arsenosugar B 2.22±0.07 µg g^–1, arsenosugar D 1.5±1.2 µg g^–1, a newly detected arsenosugar 1.13±0.07 µg g^–1, arsenosugar C 0.61±0.04 µg g^–1, DMA 0.42±0.02 µg g^–1 and these accounted for >99% of the arsenic present. The identities of all the species, except the newly detected compound, were doubly checked by matching the retention times of chromatographically pure (after the 3^rd LC dimension) species with standards and by ES MS/MS.