ONLINE SOLID-PHASE EXTRACTION THERMAL-DESORPTION GAS-CHROMATOGRAPHY WITH ION-TRAP DETECTION TANDEM MASS-SPECTROMETRY FOR THE ANALYSIS OF MICROCONTAMINANTS IN WATER

An improved set-up for solid-phase extraction with thermal desorption coupled on-line to gas chromatography (SPETD-GC) is presented, It incl udes a newly designed liner for a programmable temperature vaporizer B TV) and an improved water elimination system, The SPETD procedure now includes a washing step with HPLC-grade water to prevent degradation o f analytes due to interaction with remaining sample constituents, The system was used to analyze surface and tap water samples over a ii-mon th period, No decrease of chromatographic or trace-enrichment performa nce was observed, and a liner packed with Tenax GR could be used for a t least 150 analyses, The SPETD module was coupled to GC,vith ion-trap detection for mass spectrometric (MS) and MS/MS detection, The linear ity and repeatability of the procedure for several pesticides which we re tested in the 0.5-10 mu g/1 range were fully satisfactory (1 mu g/l , RSD range 5-11%; n = 5), When using sample volumes of 0.1 ml only, d etection limits were as low as 0.1-0.2 mu g/l. As an example, the conf irmation and quantification of a suspected pesticide in a real-life sa mple using electron impact and positive chemical ionization in both th e MS and MS/MS mode is shown.