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.