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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. [ABSTRACT FROM AUTHOR]