ION-SPRAY MASS-SPECTROMETRY FOR ELEMENTAL SPECIATION IN AQUEOUS SAMPLES - PRELIMINARY INVESTIGATION OF EXPERIMENTAL PARAMETERS, MATRIX EFFECTS AND METAL-LIGAND COMPLEXATION

Ion spray mass spectra obtained from aqueous solutions are discussed. Ion clusters with large numbers of water molecules, very few water mol ecules or bare elemental ions could be obtained by adjusting the sampl ing orifice voltage, the skimmer voltage or the position of the ion sp ray nebulizer relative to the sampling orifice. In some cases submilli meter changes in the position of the ion spray nebulizer can dramatica lly affect the nature of the spectra observed, There is evidence of de clustering between the skimmer and first ion lens as well as between t he sampling orifice and skimmer, Interpretation of the mass spectra mu st be carried out with care as potential spectral overlaps are common, Use of a triple quadrupole mass spectrometer allows assessment of pot ential spectral overlaps, Ni-EDTA complexation was investigated, The N i+ signal correlated with the expected concentration of free metal ion s in the solution not the total metal concentration even when relative ly harsh conditions that produced bare metal ion spectra were used, Ma trix effects due to high concentrations of NaCl and HCl were briefly i nvestigated.