STUDIES ON THE COMBINATION OF ION CHROMATOGRAPHY PARTICLE-BEAM MASS-SPECTROMETRY WITH CAPILLARY COLUMNS

A particle beam interface was investigated for coupling ion chromatogr aphy with mass spectrometric detection. Several prerequisites must be fulfilled, including mobile phases containing volatile buffers and hig h amounts of organic solvents at low flow-rates. Microcolumns with inn er diameters between 130 and 1000 mu m (packed with a silica-based ani on-exchange material) in combination with a microflow aerosol generato r meet these requirements. Organic solvents in the mobile phase lead t o considerable changes in separation selectivity, so that the retentio n order can be partly reversed in comparison with aqueous mobile phase s. The performance of the interface and the mass spectrometric detecti on has been studied for a series of inorganic anions as well as for am inopolycarboxylic acids and their metal complexes. The detection limit s are between 10 and 100 ng injected and are significantly poorer than those for conductivity detection. On the other hand, the possibility of operating the detector at pre-selected masses greatly improves the selectivity of the analysis and helps to confirm peaks from a non-sele ctive conductivity detector. On-line and off-line preconcentration tec hniques allow the detection of anions in drinking water at ppb levels.