离子迁移/质谱结合质谱研究含或不含NH3掺杂的电晕放电离子源中大气压化学电离机理的理论和实验研究
STUDY OF ATMOSPHERIC PRESSURE CHEMICAL IONIZATION MECHANISM IN CORONA DISCHARGE ION SOURCE WITH AND WITHOUT NH3 DOPANT BY ION MOBILITY SPECTROMETRY COMBINED WITH MASS SPECTROMETRY: A THEORETICAL AND EXPERIMENTAL STUDY离子淌度-质谱结合质谱研究含或不含NH3掺杂的电晕放电离子源中大气压化学电离机理的理论和实验研究
Younes Valadbeigi†*, Vahideh Ilbeigi‡ , Bartosz Michalczuk§ , Martin Sabo§ , Stefan Matejcik§* †Department of Chemistry, Faculty of Science, Imam Khomeini International University, Qazvin, Iran. ‡TOF Tech. Pars Company, Isfahan Science & Technology Town, Isfahan, Iran. §Department of Experimental Physics, Comenius University, Mlynska dolina F2, 84248 Bratislava, Slovak Rep.
Ionization of 2-nonanone, cyclopentanone, acetophenone, pyridine, and di-tert-butylpyridine (DTBP) in a corona discharge (CD) atmospheric pressure chemical ionization (APCI) ion source was studied using ion mobility (IMS) and time-of-flight mass spectrometry (TOF–MS). The IMS and MS spectra were recorded in the absence and presence of ammonia dopant. Without NH3 dopant, the reactant ion (RI) was H+(H2O)n, n = 3,4, and the MH+(H2O)x clusters were produced as product ions. Modeling of hydration shows that the amount of hydration (x) depends on basicity of M, temperature and water concentration of drift tube. In the presence of ammonia (NH4+(H2O)4+(H2O)x. To interpret the formation of product ions, the interaction energies of M–H+, H+–NH3, and H+–OH2 in the M–H+–NH3 and M–H+–OH2 and M–H+–M complexes were computed by B3LYP/6-311++G(d,p) method. It was found that for a molecule M with high basicity, the M–H+ interaction is strong leading in weakening of the H+–NH3, and H+–OH2 interactions in the M–H+–NH3 and M–H+–OH2 complexes.
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