Abstract: The mid-point restrictor, known as the key spare part of multidimensional gas chromatography (MDGC), was modified and applied in the determination of benzo［a］pyrene in cigarette smoke. The graphite restrictor was replaced by a 0.25 mm i.d. fused silica open tubular and the two-hole graphite ferrule was replaced by a press-fit glass Y-splitter to improve the stability of retention time on the 1st dimensional column and eliminate the carry-over effects of graphite. The cigarette samples were prepared as follows: The mainstream cigarette smoke collected on Cambridge pad was extracted with cyclohexane, then the extractant was analyzed by heart cut MDGC-mass spectrometry(MS) directly with benzo［a］pyrene-d12 as internal standard. The method was proved to be simple, sensitive, fast and reliable with good linearity (linear range of 1.47-29.4 μg/L, r2 of 0.9999), reproducibility (relative standard deviation (RSD) of 1.94%), recovery (90.74%-101.86%) and low quantitative and qualitative detection limits. Moreover, the amount of benzo［a］pyrene in the 2R4F Kentucky reference cigarette smoke obtained by this method was close to that reported in literature.

Key words: benzo［a］pyrene, cigarette smoke , mass spectrometry (MS), multidimensional capillary gas chromatography (MDGC), mid-point restrictor