An ion-interaction RP-HPLC method for the determination of the eleven EPA priority pollutant phenols

An ion-interaction RP-HPLC method is presented for the simultaneous separation and determination of the eleven EPA priority pollutant phenols. The method is based on the capability of phenolic compounds to form ion- pairs with alkylammoniumions. The optimised mobile phase is a water/acetonitrile solution of octylammonium o-phosphate at pH 8. With UV detection at 285 nm, determination limits lower than 30 μg 1^-1 are achieved, without preconcentration. By the use of statistical tests, the accuracy and the reproducibility of the method is tested (confidence level 95%) with respect to EPA certified standard solution and the method is validated through intercalibration with a GC-MS method. The statistical difference between the methods is evaluated by parametric (F-test, paired t- test, t-test for multiple samples) and non parametric tests (Mann-Whitney, U- test and Wilcoxon test) and the results are discussed. Accuracy, reproducibility and detection limit of the IIR-HPLC method resulted to be more advantageous with respect to gas-chromatographic methods. Examples of preconcentration and application to the analysis of river water are presented.