Determination Of Phthalate Ester Residues In Liquor By GC -Isotope Dilution Mass Spectrometry

Phthalate esters are a kind of additive plasticizer, widely used in plastic products. They can be absorbed in human body through drinking, eating, skin contacting, breathing and other ways, producing reproductive and developmental toxicity, and even leading to cancers. Dimethyl phthalate (DMP) and Diethyl phthalate (DEP) are frequently appeared in liquor.The thesis studies the analytical methods of DMP and DEP in liquor by gas chromatography - isotope dilution mass spectrometry. Details are as follows.1、The analytical method of DMP and DEP in liquor using the general external standard method by gas chromatography - trip le quadrupole mass spectrometer was investigated. The method shows that a good linear relationship with correlation coefficient of DMP r2= 1.00000, and DEP r2= 0.99964. But the recoveries of DMP and DEP using two pre-treatment methods of liquid-liquid extraction and nitrogen blowing-dissolution method are all low.In the range of 0.2-1.2 mg/L, the recoveies of DMP and DEP by liquid-liquid extraction are 9.8%-36.2% and 25.6%-61.4%, respectively. The recovery is much lower by nitrogen blowing- dissolution (3.1%-5.5%). So, the result presents that general external standard method is unsuitable for the accurate analysis of low concentration DMP and DEP in liquor after liquid-liquid extraction or nitrogen blowing-dissolution pre-treatment2、The isotopic abundances and chemical purities of deuterated dimethyl phthalate (DMP-D6) and deuterated diethyl phthalate (DEP-D10) made in Shanghai Research Institute of Chemical Industry were characterized. The isotopic abundances of DMP-D6 and DEP-D10 were determined by LC-MS and calculated by "quality cluster" method, in which the abundance of DMP-D6 is 99.44atom%, and the DEP-D10 is 99.10atom%. The chemical purity was determined by gas chromatography. The linear correlation coefficients of DMP and DEP were r2=0.99934 and r2=0.99999, respectively. The chemical purity of DMP-D6 is determined as 99.60%, and DEP-D10 as 99.28%. The recoveries of the method are 101.2%- 101.9% for DMP-D6 and 99.4%-100.1% for DEP-D10. The RSD% of peak areas are less than 0.5%(n=6). The isotopic abundance and chemical purity can meet the requirement of isotope internal standard reagents.3、The method for analyzing DMP and DEP in liquor by gas chromatography tandem triple quadruple mass spectrometry (GC-MS/MS) with isotopic internal standards was established, using DMP-D6 and DEP-D10 made by Shanghai Research Institute of Chemical Industry. The determination method was validated by experiments. For DMP, the limit of detection (LOD) was 0.3 ng/mL and limit of quantification (LOQ) was 0.8 ng/mL, the recovery was 95.0%±2.6% For DEP, The LOD was 0.1 ng/mL, LOQ was 0.4 ng/mL, and the recovery was 80.0%±3.4% The method meets the demand of phthalate esters detecting in liquor and seven real liquor samples from market is detemined, which present the method sensitive, accurate and simple.