Trace determination of diethylphthalate in aqueous media by solid-phase microextraction-liquid chromatography

The development, optimisation and validation of a method for the determination of trace levels of diethylphthalate (DEP) in aqueous media is described. Extraction is by solid-phase microextraction followed by HPLC analysis. The compound is spiked into 10-ml aliquots of ultra-pure water to which 2.5 g of NaCl is added. DEP is separated from other co-extracted components on a Nucleosil C-18 column 5 mu m dp 250X3.2 mm I.D. The mobile phase is acetonitrile-water (52.5:47.5). delivered at a flow-rate of 0.5 ml/min. The column is thermostatted at 30 degrees C and detection is by ultraviolet absorbance at 226 nm. Optimisation of the method is discussed, and the precision, accuracy and linearity using both a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre and a carbowax/templated resin (CW/TPR) fibre were determined. The PDMS/TPR fibre extracted the DEP more efficiently than the CW/TPR fibre with a limit of detection of 1 ng/ml for an immersion time of 15 min. (C) 1999 Elsevier Science B.V. All rights reserved.