SEPARATION AND DETERMINATION OF ACIDIC HERBICIDES ON A PRP-1 POLYMERIC COLUMN

The chromatographic behavior of some acidic herbicides (phenoxyacetic acids, bentazon and dicamba) was investigated on a column laboratory-packed with PRP-1, using acetonitrile-water as mobile phase. Detection was performed with a UV detector set at 220 nm. This wavelength was selected as the optimum for the simultaneous determination of the herbicides. The elution of acidic compounds is affected by the pH of the mobile phase. The greates retention and the best peak symmetry were observed at pH 2.3. The relationships between log k′ and acetonitrile volume fraction (φ{symbol}) in the mobile phase are parabolic. The detection limits of the tested substances were abount 0.2 ng in the volume injected. The capacity factors in pure water (k′w), extrapolated by a quadratic expression, showed that PRP-1 could be effective in extracting the examined compounds from water. Various experiments, carried out on spiked water samples using commercial PRP-1 cartridges, showed that the recovery of examined herbicides is nearly 100%. Further, such traps could make it possible to concentrate aqueous samples containing acidic herbicides at very low levels (ppt). © 1990.