MEMBRANE SOLID-PHASE EXTRACTION WITH CLOSED VESSEL MICROWAVE ELUTION FOR THE DETERMINATION OF PHENOLIC-COMPOUNDS IN AQUEOUS MATRICES

Preconcentration of phenolic compounds was carried out with Empore C-1 8 membrane disks, which were eluted with a closed-vessel microwave ext raction system. The optimum microwave-elution conditions were obtained by optimizing the elution solvent, elution temperature, duration of e lution and volume of elution solvent. The recoveries of eleven phenoli c compounds spiked at 10 and 500 mu g/L levels into water, using the o ptimum conditions, were al above 85% with relative standard deviations between 4.0 and 10.0%, except for phenol and 4-nitrophenol. Extractio n of an industrial waste water sample suspected of containing phenolic compounds by SPECVME showed similar recoveries of phenol (the only ph enolic compound detected) when compared with LLE and C-18 SPE cartridg e techniques. Analysis of phenolic compounds was carried out using liq uid chromatography coupled to a UV detection system.