EVALUATION OF MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS-SPECTROMETRY FOR THE ANALYSIS OF ORGANOARSENIC COMPOUNDS OF ENVIRONMENTAL INTEREST

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was investigated for arsenic speciation of compounds of environmental interest. It is a very sensitive mass spectrometric technique which can detect as little as 0.3 ng of arsenic or 4 pmol of the arsenical under investigation. This feature suggests that the method could be used for the identification of minor arsenic components in environmental samples, Additional advantages of the technique are its capability of providing molecular ions as well as fragment ions for a variety of arsenicals, and allowing for a certain degree of control in compound fragmentation, by adjusting the N-2 laser power. Quantitative analysis by MALDI-TOF-MS is still considered a highly unreliable procedure since many variables associated with sample preparation and analytical procedure can seriously affect the results.