CONTINUOUS LIQUID-LIQUID-EXTRACTION COMBINED ONLINE WITH CAPILLARY GAS-CHROMATOGRAPHY ATOMIC-EMISSION DETECTION FOR ENVIRONMENTAL-ANALYSIS

The on-line coupling of a liquid-liquid extraction system with capilla ry gas chromatography using atomic emission detection (GC-AED) has bee n studied. The required large volumes of about 100 mu l of an iso-octa ne solution can be introduced into the GC-AED system by using the AED solvent vent and a solvent vapor exit in front of the capillary analyt ical column. Test solutions containing several pesticides were detecte d using the carbon, chlorine, nitrogen and sulfur channels. Analyte de tectability (in concentration units) was improved significantly and lo w concentrations of the test compounds could be determined (1-5 ng/ml) . Aqueous samples were on-line extracted and analyzed. The precision o f the large-volume injection itself as well as the total extraction-GC -AED system was satisfactory (RSD of ca. 2 and 4%, respectively). As a real-life application, several ground water samples were screened.