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

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, AsV 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 3rd LC dimension) species with standards and by ES MS/MS.