GC-MS Determination of Di-(2-ethylhexyl)-phthalate in Water with Micro-solvent Extraction

3.0g of anhydrous Na2SO4 was added to 25 mL of the water sample, which was then extracted by shaking for 3 min with 2.0 mL of cyclohexane. 2.0 μL of the supernatant organic phase containing di-(2-ethylhexyl)-phthalate (DEHP), was introduced into the HP-5 (30 m×0.32 mm, 0.25 μm) capillary chromatographic column, separated and determined by MS. Linear relationship between values of peak area and mass concentration of DEHP was obtained in the range within 50.0 μg·L-1, with detection limit (3S/N) of 0.052 μg·L-1. Three samples of the tap water collected in the morning, noon and night, were analysed by this method, and recovery was tested by standard addition method, giving values of recovery in the range of 97.0%-109.4%, with RSD′s (n=6) less than 2.5%.