OBSERVATIONS ON THE USE OF ION-SPRAY MASS-SPECTROSCOPY FOR ELEMENTAL SPECIATION IN AQUEOUS-SOLUTIONS WITHOUT RECOURSE TO CHROMATOGRAPHY

This paper describes preliminary experiments that are selected with th e limited aim of assessing whether ion spray (IS) mass spectrometry, i n its current state of development, is a viable technique for practica l speciation without recourse to the use of chromatography, Further, i t attempts to demonstrate that the ion spray interface, in contrast to electrospray ion generation, can handle, without modification, wholly aqueous media as well as mixed solvents and organic solvents, The ins trumentation employed for this study was an unmodified, commercially a vailable, triple quadrupole mass spectrometer. Thus, experiments are d escribed which demonstrate the capability of IS to provide speciation information on, in this case, Ni in aqueous and methanolic media with and without the presence of the chelating ligand, EDTA, Additional exp eriments are reported for aluminium in combination with citric acid, T he results confirm previous work and show that the source and interfac e conditions can be tailored to provide either molecular information o r to reveal the presence of elements as their elemental ions, Aqueous solutions are handled successfully by the IS interface without modific ation and reveal the expected speciation patterns, However, several pr oblems were encountered: the spectra, even for single component soluti ons, are complex and highly sensitive to operating conditions; new spe cies can be generated in the ionisation-extraction process and conditi ons have to be tailored to ions of a particular polarity; elemental se nsitivity is limited; and care has to be taken to avoid sample carry o ver, Given the complexity of the spectra, it is concluded that real sa mples will require prior separation by chromatographic or electrophore tic techniques and that MS-MS instrumentation is of considerable value for confirming the identification of individual species.