Determination of phenols in environmental waters using liquid chromatography with electrochemical detection

The development of a liquid chromatographic method for the determination of priority pollutant phenols at low mu g/l levels in environmental waters is discussed. The phenols were separated using a Nova-Pak Phenyl column with concave gradient elution from 20 mM ammonium acetate (19% acetonitrile) to 20 mM ammonium acetate (54% acetonitrile) over 12 min, and subsequently detected using an electrochemical detector equipped with a glassy carbon working electrode, operated at a potential of + 1150 mV. This approach resulted in minimal sample interferences and practical quantitation limits in the low mu g/l range. The LC-ED method offers a distinct advantage over the established GC and GC-MS phenol methods in that no sample extraction is required, hence avoiding the losses which occur during the extraction, concentration and solvent exchange steps required for the GC-based analyses. The method was evaluated through participation in a round robin testing program, involving determination of the eleven priority pollutant phenols in environmental water matrices. The results and recoveries obtained using the LC-ED method compared well with the overall consensus results, with recoveries ranging from 75% up to 118% for the eleven phenols. The between-laboratory reproducibility data indicated a high level of collective proficiency, with the overall average coefficients of variation for the eleven analytes being 18%, 18% and 13%, for spiked oil refinery effluent, paper mill effluent and reagent water samples, respectively.