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

The fully automated on-line trace enrichment of 27 (polar) pollutants, usin g volumes of up to 1,000 mL, on a polymeric precolumn followed by liquid ch romatography - diode-array detection has been studied. Various parameters i nfluencing the reproducibility of these large volume injections like breakt hrough volume, precolumn capacity, matrix effects, and enrichment flow rate are discussed. The relative standard deviation of the recoveries after enr ichment of 25-500 mL, of sample is 1-20 %. Enrichment flow rates up to 15 m L 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 breakt hrough volumes show significant dependence upon the concentration of the an alytes in the sample.