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
離子淌度-質譜結合質譜研究含或不含NH3摻雜的電暈放電離子源中大氣壓化學電離機理的理論和實驗研究
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,Bratislava, Slovak Rep.
Abstract
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.
使用離子遷移率(IMS)和時間分析法研究了電暈放電(CD)大氣壓化學電離(APCI)離子源中的2-壬酮，環戊酮，苯乙酮，吡啶和二叔丁基吡啶(DTBP)的電離飛行質譜(TOF–MS)。在不存在和存在氨摻雜劑的情況下記錄IMS和MS光譜。在沒有NH 3摻雜劑的情況下，反應物離子(RI)為H +(H 2 O)n，n = 3,4，并且生成了MH +(H 2 O)x 簇作為產物離子。水合模型表明水合量(x)取決于M的堿度，溫度和漂移管的水濃度。在氨水(NH 4+(H 2 O)Ñ作為RI)兩種產物離子，MH的+(H 2 O)X 和MNH 4 +(H 2 O)X，制備，這取決于M的堿度隨著NH 4 +( H 2 O)n 為RI，較高堿度的吡啶和DTBP的產物離子為MH +(H 2 O)x， 而較低堿度的環戊酮，2-壬酮和苯乙酮產生MNH 4 +(H 2 O)x。為了解釋產物離子的形成，需要 考慮M–H + –NH 3 和M–H + –OH 2 和M–H 中M–H +，H + –NH 3和H + –OH 2的相互作用能+ –M配合物通過B3LYP / 6-311 ++ G(d，p)方法計算。研究發現，對于具有高堿性的分子M，M–H + 相互作用很強，導致 M–H + –NH 3 和M– 中的H + –NH 3和H + –OH 2相互作用減弱。H + –OH2個 復合體。
