Investigation of arsenic species in Hizikia fusiforme algae using highly efficient gradient ion-exchange LC-ICP-MS and LC-ESI-MSn

WUILLOUD, RODOLFO G.; C. ALTAMIRANO, JORGELINA; HEITKEMPER, DOUGLAS

Portland, Oregon

Congreso; 31st FACSS (THE FEDERATION OF ANALYTICAL CHEMISTRY AND SPECTROSCOPY SOCIETIES) CONFERENCE; 2004

THE FEDERATION OF ANALYTICAL CHEMISTRY AND SPECTROSCOPY SOCIETIES

Arsenic speciation is necessary due to the extreme toxicity differences that its compounds have in the environment and biological systems. This element can be accumulated in marine plants and animals up to concentrations of several hundreds of mg kg-1. Arsenic biotransformations in algae or seaweeds are known to produce a wide range of organoarsenic compounds in high concentrations (arsenosugars), while the inorganic species, As(III) and As(V) have been generally found at low concentration levels.  However, high concentration levels of As(V) (10 mg kg-1) have been reported in a particular edible algae commercially named Hijiki or Hiziki (Hizikia fusiforme).Various analytical methodologies coupling ion exchange liquid chromatography to inductively coupled plasma mass spectrometry (ICP-MS) or electrospray ionization mass spectrometry (ESI-MS) have been employed in the past for arsenic speciation in Hizikia fusiforme algae. Although chromatographic separation of arsenic species in this algae was previously reported, incomplete information on the arsenic speciation was obtained and several unknown peaks were reported as a consequence of poor chromatographic resolution.In this work, a highly efficient chromatographic method involving the coupling of anion- and cation-exchange separation to ICP-MS and ESI-MS is presented for obtaining complete arsenic speciation information in Hizikia fusiforme algae. The HPLC system was coupled on-line with ICP-MS or ion trap MS to obtain elemental-specific and molecular information, respectively. The effect of different chromatographic variables on the resolution of arsenic species was studied.  Significant differences between isocratic and gradient chromatographic modes were noted. The final separation conditions were compatible with both ICP-MS and ESI-MS detectors avoiding peak collections and allowing fast arsenic species identification and determination. Finally, the proposed methodology was applied to the evaluation of arsenic species present in several commercially available samples of Hizikia fusiforme.