[Modification of mid-point restrictor of heart cut multidimensional gas chromatography-mass spectrometry system and its application in analysis of benzo [a] pyrene in cigarette smoke].

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 microg/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.