配标溶剂对双区大气压化学电离质谱分析环境烟气标志物3-乙烯基吡啶的影响

为探讨配标溶剂对双区大气压化学电离-质谱（DRAPCI）源内溶剂效应造成的影响，以环境烟气（ETS）标志物3-乙烯基吡啶（3-EP）为研究对象，以环己烷、甲醇、丙酮和乙腈为配标溶剂，考察3-EP在不同溶剂背景下离子化效率的差异，探讨造成差异的原因，并比较不同配标溶剂下方法的分析性能。结果表明:①配标溶剂的选择会影响3-EP的离子化效率，从而限制方法的检出限和定量限，通过营造不同的溶剂氛围发现3-EP的离子化效率差异可能是质子竞争和中性分子团簇包埋共同作用的结果。在此基础上，确定环己烷为配标溶剂并建立ETS中3-EP分析的DRAPCI-MS方法，该方法检出限（0.38 ng/L）和定量限（1.15 ng/L）低，在低浓度范围区域线性良好（R2=0.996 4）。②对ETS中3-EP变化的动态监测显示选择合适配标溶剂建立的方法可延长动态检测时间范围，更好地呈现环境烟气动态变化的特征，表明采用常压质谱法进行定量分析时必须考虑溶剂效应可能造成的干扰，应优化配标溶剂的组成和用量。 

Effects of standard solvents on analysis of 3-ethenylpyridine as a marker of environmental tobacco smoke by DRAPCI-MS

In order to investigate the solvent effects on double-region atmospheric pressure chemical ionization-mass spectrometry (DRAPCI-MS) source, the differences in the ionization efficiency of 3-ethenylpyridine (3-EP) as an environmental tobacco smoke (ETS) marker were analyzed by using different standard solvents. These included cyclohexane, methanol, acetone and acetonitrile, and the reasons for causing those differences were studied and the performances of this method with the different standard solvents were compared. The results showed that: 1) The standard solvents affected the ionization efficiency of 3-EP, thereby influenced the limit of detection (LOD) and the limit of quantification(LOQ)of the method. By creating different solvent atmospheres, it was found that the differences in the ionization efficiency of 3-EP might be the results of the combined action of proton competition and cluster embedding of neutral molecules. On that basis, a DRAPCI-MS analysis method for 3-EP was developed by taking cyclohexane as the standard solvent. The LOD and LOQ of the developed method were 0.38 and 1.15 ng/L respectively. The calibration curve was obtained at a low concentration range with a satisfactory regression coefficient of 0.996 4. 2) The dynamic detection of 3-EP variations in ETS indicated that a suitable standard solvent could extend the time range of dynamic detection and well represented the characteristics of dynamic variation of ETS. It was necessary to consider the possible interference caused by the solvent effect and to optimize the ratio and dosage of the standard solvent when adopting atmospheric MS for quantitative analysis.