A gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of 46 plasticizers in food contact polyvinyl chloride (PVC) packaging materials and their migration into food simulants, i. e. water, 3% acetic acid, 10% ethanol and olive oil. Plasticizers in the PVC packaging materials, aqueous food simulants and olive oil food simulants were extracted by the dissolution-precipitation, liquid-liquid extraction and gel permeation chromatography (GPC) approaches, respectively. The extracts were analyzed by GC-MS in selective ion monitoring (SIM) mode and quantified using the external standard method. The cal-ibration curves were linear in the ranges of 0.1-2.0 mg/L with the correlation coefficients of 0.9910-0. 999 9. The limits of detection were from 0. 005 mg/kg to 0. 05 mg/kg ( S/N = 5 ). The recoveries at 3 spiked levels were 69.51%-107. 21% and the relative standard deviations (RSDs n = 6) ranged from 3.53% to 18.95%. These results show that this method is fast, sensitive and accurate for the qualitative and quantitative determination of plasticizers in food contact plastic products and 4 types of food simulants.

A sensitive and selective method is presented for the determination of paraquat residue in fruits, vegetables, beans and grain by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Paraquat in samples was extracted with water and cleaned-up with a weak cation exchange (WCX) column to obtain an extract suitable for analysis using HPLC-MS/MS. The paraquat was separated by a CAPCELL PAK ST column (150 mm x 2.0 mm) and with acetonitrile-10 mmol/L ammonium acetate solution (adjusted to pH 4.0 by formic acid) as the mobile phase, and multiple reaction monitoring (MRM) was used with electrospray ionization in the positive ion mode. The calibration curve was linear between the peak area and the mass concentration of paraquat from 0.01 to 0.1 mg/L with the correlation coefficient of 0.993. Recoveries of paraquat spiked in samples at three levels ranged from 84.0% to 106.0% with the relative standard deviations of 7.8% - 18.8%. The limits of detection (LODs) of paraquat were 0.01 mg/kg in fruits and vegetables and 0.05 mg/kg in beans and grain. The LODs can meet the requirements of international maximum residue limit.

The oils extracted by hydro distillation from the aerial parts of Artemisia scoparia waldst. & kitag growing wild in two regions on Qinghai-Tibetan Plateau were analyzed by GC-MS. Eighty-three components were identified representing 97.5% of the total components detected. The major constituents of the oil from the samples obtained in the eastern of Riyue Mountain (2700 -3200 m) were 2-ethenyl-naphthalene (45.1%), beta-pinene (11.2%), 3-carene (8.7%), 3,7-dimethyl-1,3,6-octatriene (7.9%), limonene (5.4%), alpha-pinene (3.5%) and beta-myrcene (2.0%). Whereas the oil from the plant collected in Qilian Mountain (3300 -3500 m) was composed mainly of thujone (21.4%), 1,8-cineole (18.9%), camphor (9.1%), 4-methyl-1-(1-methyl ethyl)-3-cyclo hexen-1-ol (7.8%), 4-methyl-1-(1-methylethyl)-bicyclo[3.1.0]hexan-3-one (5.3%) and 2-isopropyl-5-methyl-3-cyclohexen-1-one(5.0%).