Ion mobility spectrometry （IMS） is a very fast, highly sensitive, and inexpensive technique, it permits efficient monitoring of volatile organic compounds like alcohols. In this article, positive ion mobility spectra for six alcohol organic compounds have been systematically studied for the first time using a high-resolution IMS apparatus equipped with a discharge ionization source. Utilizing protonated water cluster ions （H2O）nH^＋ as the reactant ions and clean air as the drift gas, alcohol organic compounds, ethanol, 1- propanol, 2-propanol, 1-butanol, 1-pentanol and 2-octanol, all exhibit product ion characteristic peaks in their respective ion mobility spectrometry, that is a result of proton transfer reactions between the alcohols and reaction ions （H2O）nH^＋. The mixture of these alcohols, including two isomers, has been detected, and the results showed that they could be distinguished effectively in the ion mobility spectrum. The reduced mobility values have been determined, which are in very well agreement with the traditional ^63Ni-IMS experimental values. The exponential dilution method was used to calibrate the alcohol concentrations, and a detection limit available for the alcohols is in order of magnitude of a few ng/L.
HAN Hai-yan HUANG Guo-dong JIN Shun-ping ZHENG Pei-chao XU Guo-hua LI Jian-quan WANG Hong-mei CHU Yan-nan
Ion mobility spectra for ten alcohols have been studied in an ion mobility spectrometry apparatus equipped with a corona discharge ionization source. Using protonated water cluster ions as the reactant ions and clean air as the drift gas, the alcohols exhibit different product ion characteristic peaks in their ion mobility spectra. The detection limit for these alcohols is at low concentration pmol/L level according to the concentration calibration by exponential dilution method. Based on the measured ion mobilities, several chemical physics parameters of the ion-molecular interaction at atmosphere were obtained, including the ionic collision cross sections, diffusion coefficients, collision rate constants, and the ionic radii under the hard-sphere model approximation.
以《大气污染物综合排放标准))(GB 16297-1996)中有机物的实时在线测量为目的,对自行研制的质子转移反应质谱(proton transfer reaction mass spectrometry,PTR-MS)装置的参数进行了优化和测量。利用高纯N_2稀释的单一有机物PTR-MS测量结果表明,在E/N=144 Td条件下,质子化的有机物离子为主要的产物离子峰,没有明显的碎片离子存在。测试了进样系统中催化转化装置的性能,给出了11种挥发性有机物的探测灵敏度和检测下限,讨论了PTR-MS的测量精度。测试结果表明,自行研制的PTR-MS能够实时在线监测《大气污染物综合排放标准》中规定的有机污染物。
