ONLINE PRECONCENTRATION OF AQUEOUS SAMPLES FOR GAS-CHROMATOGRAPHIC MASS-SPECTROMETRIC ANALYSIS

On-line trace enrichment as a treatment for the analysis of water samples by gas chromatography (GC) with subsequent detection by mass spectrometry (MS) is demonstrated. A 1 cm3 sample is concentrated on a short polymer-packed liquid chromatography (LC) pre-column. After rinsing with high-performance LC-grade water, the pre-column is dried with nitrogen and desorbed with ethyl acetate. A fraction of 60 mm3 is introduced on-line into a diphenyltetramethyldisilazane-deactivated retention gap. After evaporation of the solvent via an early solvent-vapour exit, the analytes are separated by means of GC and introduced into the ion source of the mass spectrometer via a restriction capillary. With the mass spectrometer as a sensitive and selective detector for on-line LC-GC, atrazine and other triazines can be determined in water at the low parts per trillion level.