title: Ambient ionization and direct identification of volatile organic compounds with microwave-induced plasma mass spectrometry.
abstract: An innovative method of volatile organic compounds analysis by using microwave-induced plasma ionization (MIPI) source in combination with an ambient ion trap mass spectrometer is presented here. Using MIPI for direct sample vapor, analysis was achieved without any sample preparation or subsequent heating. The relative abundance of the target compounds can be obtained almost instantly within a few seconds. The ionization processes of different volatile compounds was optimized, and the limits of detection were identified in the range of 0.15-4.5 pptv or 0.73-8.80 pg ml(-1). The relative standard deviation (RSD) is in the range of 4-14%, while correlation coefficients of the working curves (R(2)) are better than 0.98. The new method possesses advantages of ease operation, time-saving, high sensitivity and inexpensive setup. In addition, the ionization processes of short n-alkane chains were investigated with the MIPI technique, and a unique [M + 13](+) was detected, which has not been reported in detail by any other related ionization techniques. An ionization mechanism was proposed on the basis of the experimental results obtained in this work and available information in literatures, in which the n-alkanes in the plasma environment possibly generate protonated cyclopentadiene [M - 5](+) or alkyl-substituted analogues as well as hydrous ions [M + 13](+) and [M + 13 + 18](+), as shown in Scheme 1 in the main text.
authors: Research Center of Analytical Instrumentation, College of Chemistry, Sichuan University, Chengdu, China, 610064.
authors: Dandan
authors: D
authors: Li
authors: Yong-Hui
authors: YH
authors: Tian
authors: Zhongjun
authors: Z
authors: Zhao
authors: Wenwen
authors: W
authors: Li
authors: Yixiang
authors: Y
authors: Duan
mesh_terms: D000473:Alkanes; D004867:Equipment Design; D007477:Ions / Q000032:analysis / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D008872:Microwaves; D015203:Reproducibility of Results; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000737:chemistry*
chemical_list: D000473:Alkanes; D007477:Ions; D055549:Volatile Organic Compounds
keywords: ambient mass spectrometry; ionization mechanism; microwave-induced plasma; n-alkanes; volatile organic compound