LIQUID-CHROMATOGRAPHY ELECTROCHEMISTRY PROCEDURE FOR THE DETERMINATION OF CHLOROPHENOLIC COMPOUNDS IN PULP-MILL EFFLUENTS AND RECEIVING WATERS

An isocratic, reversed-phase liquid chromatography procedure is described for the separation and determination of chlorophenolic compounds, including several priority pollutant chlorophenols. The separation was experimentally optimised, and selective and sensitive detection was obtained by dual electrode amperometry. The most suitable combination was a silica-based column with phenyl functional groups, and a mobile phase of acetonitrile-acetate buffer (40:60, pH 5). Dual glassy-carbon electrodes were used in a parallel configuration in a thin-layer flow cell, with differential current measurement (+0.90 V relative to +0.60 V). A solid-phase extraction scheme using a polymeric sorbent (Chromosorb 102) was devised for the extraction and preconcentration of selected chlorophenols, chloroguaiacols, and a chlorosyringol from aqueous samples. Use of tribromophenol as an internal standard was also investigated. The total procedure-preconcentration and chromatography-was applied to the analysis of effluents discharged by a paper mill, and a pulp mill.