Neutral Aromatic Components from Cigarette Smoke by Isotope Dilution-GC/MS

A method of isotope dilution-gas chromatography-mass spectrometry (ID-GC/MS) was developed for analysis of 10 kinds of neutral trace aromatic components (benzaldehyde, 6-methyl-5-hepten-2-one, furfuryl acetate, methyl benzoate, isophorone, 2,4-dimethyl-acetophenone, 2-undecanone, geranyl acetone, β-ionone and benzyl benzoate) from cigarette smoke. 10 isotope markers (D₅-benzaldehyde, ¹³C₃-6-methyl-5-hepten-2-one, D₃-furfuryl acetate, D₅-methyl benzoate, D₈-isophorone, D₃-2,4-dimethyl acetophenone, ¹³C₃-2-undecanone, ¹³C₃-geranyl acetone, D₄-β-ionone, D₅-benzyl benzoate) corresponding to neutral aromatic components were added to Cambridge filter for collecting particles of cigarette smoke，and the aromatic components were extracted by simultaneous distillation and extraction method. The acidic and basic components in the extract were removed by washing with 5% hydrochloric acid and 5% sodium hydroxide aqueous solution (concentrations of volume percent), respectively, and the neutral components extract were obtained. The neutral aromatic components were analyzed by GC/MS under optimized conditions. The molecular ions and characteristic fragment ions with isotope atoms of isotope markers were selected as qualitative ions in qualitative identification in order to identify the corresponding target components. The qualitative identification of the target components in extract was assisted by the labeling effect of isotopes because of the addition of isotope markers, and the neutral aromatic components were identified reliably by comparing with characteristic fragments of isotope markers and retention time of reference standards in complex system. Many separation methods such as solid-phase microextraction (SPME) and preparative HPLC were omitted from the samples pretreatment process and the sample consumption was rather reduced. Two quantitative ions with higher signal-to-noise ratio and less interference were selected for each compound in quantitative analysis. The target neutral components in extract were analyzed by GC/MS using quantitative ions in SIM mode, and the results showed that the separation of target compounds from interfering components was completely and the accurate quantitative analysis could be carried out. The contents of 10 neutral components were simultaneous determined by internal standard curve method using corresponding isotopes as internal standard. The analysis results showed that the correlation coefficients are greater than 0.999 0, the limits of detection (LODs) are 0.34-4.59 μg/kg, and the limits of quantity (LOQs) are 1.14-15.30 μg/kg. The average recovery is in the range of 83.3%-106.6%, and the relative standard deviations (RSDs) are in the range of 0.15%-8.69%. This method is sensitive and accurate，which is suitable for quantitative analysis of neutral aromatic components in cigarette smoke.