Separation of two groups of oestrogen mimicking compounds using micellar electrokinetic chromatography

Two groups of compounds are being investigated due to their reported oestrogen mimicking characteristics in the environment. Separation of phenolic compounds and synthetic oestrogens using micellar electrokinetic chromatography is reported. Photodiode array detection is used for both separations. A standard separation buffer can be used for both groups of compounds including zwitterionic buffer cyclohexylamino-1-propanesulfonic acid, 20 mM at pH 11.5. It was found necessary to include 15% acetonitrile and 25 mM sodium dodecyl sulfate to aid separation and maintain analytes in solution. Optimum separations are achieved using 20 kV with hydrodynamic injection for 5 s. The relative standard deviation (RSD) for reproducibility was investigated for a mixture of phenols and synthetic oestrogens. For these compounds RSD was found to be <0.6% in all cases. Peak efficiencies ranged from 76,000 to 150,000 theoretical plates for different analytes. Application to environmental samples is discussed.