Simultaneous determination of phthalate di- and monoesters in poly(vinylchloride) products and human saliva by gas chromatography–mass spectrometry

A gas chromatographic–mass spectrometric (GC–MS) method using selected ion monitoring (SIM) is described for the simultaneous determination of phthalate di- and monoesters in poly(vinylchloride) (PVC) products. The method consists of the following four procedures; (1) liquid–liquid extraction with ethyl acetate from the acidified aqueous homogenates of the PVC products, (2) esterification with trimethylsilyldiazomethane (TMSD) and methanol, (3) clean-up using Florisil column chromatography and (4) quantitative determination of methylated phthalate monoesters by GC–MS using SIM. The methylated monoesters show a characteristic mass fragment pattern at m/z 163, 149 and 91. The calibration curves for the monoesters were linear from 0.05 to 10 ng (injection volume 1 μl). Overall recoveries ranged from 86.6 to 94.3%. The limits of detections for these methylated derivatives were in the range of 2.0–5.0 ng/g (S/N=3). This method was applied to phthalate monoesters in PVC toy products. Mono-n-butyl phthalate and mono-2-ethylhexyl phthalate were found at levels of 6.42–11.62 μg/g and 30.50–41.81 μg/g, respectively. No monoethyl phthalate, mono-n-hexyl phthalate and monobenzyl phthalate were found in the toy products. The method was also applied to these compounds in human saliva.