Large-volume liquid chromatographic trace-enrichment system for environmental analysis

The fully automated on-line trace enrichment of 27 (polar) pollutants, using volumes of up to 1,000 mL, on a polymeric precolumn followed by liquid chromatography - diode-array detection has been studied. Various parameters influencing the reproducibility of these large volume injections like breakthrough volume, precolumn capacity, matrix effects, and enrichment flow rate are discussed. The relative standard deviation of the recoveries after enrichment of 25-500 mL, of sample is 1-20 %. Enrichment flow rates up to 15 mL min(-1) can be used with an optimum at 10 mL min(-1). A pore size of 300 A provides the best results using the polymeric PLRP-S material. The breakthrough volumes show significant dependence upon the concentration of the analytes in the sample.