[Application of single drop microextraction in the determination of phthalate esters and parabens in drugs by gas chromatography-mass spectrometry].

Single drop microextraction (SDME) was used for the determination of phthalate esters and parabens in drugs by gas chromatography-ion trap mass spectrometry (GC-IT/MS). The effects of the nature of extraction solvents, microdrop volume, the depth of microdrop in sample solution, extraction time and stirring rate on the extraction efficiency were investigated separately. The optimal SDME conditions, 1.5 microL of toluene, 0.8 cm of the depth of microdrop, 1 000 r/min of stirring rate and 20 mm of extraction time, were obtained and used for the analysis of methylparaben (MP), ethylparaben (EP), propylparaben (PP), iso-propylparaben (IPP), butylparaben (BP), dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP) in drugs. The results showed that the working curves for 8 phthalate esters and parabens were linear in the range of 0.032 - 80 mg/L by GC-MS on selective ion storage mode. The limits of detection (LOD) were between 0.6 microg/L and 1.28 mg/L, the overall recoveries were 95.85% - 148.85% with the relative standard deviations of 3.9% - 14.9%.