Determination of organochlorine pesticide residues in tobacco by gas chromatography-negative chemical ionization time of flight mass spectrometry

A method was developed for the determination of 10 organochlorine pesticide (OCP) residues in tobacco by gas chromatography-negative chemical ionization-time of flight mass spectrometry (GC-NCI-TOF-MS) coupled with QuEChERS method. The extraction and purification procedures for tobacco samples, the chromatographic conditions and TOF-MS conditions of the analytes were critically examined. Tobacco samples were extracted with ethyl acetate-hexane (1 :1, v/v) and cleaned up by primary secondary amine (PSA) and MgSO4, then detected by GC-NCI-TOF-MS. Accurate mass analysis, isotopic peak clusters, fragment ion abundance ratio and retention time were employed to qualitative identification and external standard method was used for quantitative determination. The results indicated that the correlation coefficients (r(2)) were better than 0. 997, and the relative standard deviations (RSDs) were less than 6. 5%. The limits of detection and the limits of quantification were 0. 04 to 0. 80 g/kg and 0. 13 to 2. 64 mu g/kg, respectively. The recoveries of the 10 organochlorine pesticides at three spiked levels ranged from 77. 2% to 93. 0%. It was proved that the method is simple, rapid, with high accuracy and high sensitive. It is appropriate for the detection and determination of organochlorine pesticide residues in tobacco samples.