On-line trace enrichment of difenzoquat in water and its determination by HPLC.

A high performance liquid chromatographic method involving an integrated enrichment step is described for the quantitative determination of low levels of difenzoquat residues in water. Difenzoquat is trapped from the flowing water sample by strong adsorption onto the enrichment column. It is then desorbed, separated, and subsequently analyzed in a single step process by reverse phase high performance liquid chromatography using ultraviolet detection at 255 nm. Average recovery of difenzoquat from organic free water at spiking levels of 20, 10 and 5 ppb was 97.0%. The lower detection limit reached was 0.25 ppb difenzoquat in organic free water.