بررسي جداسازي تركيبات ايزومري (ساختاري و نوري) در طيف سنج تحرك يوني با استفاده از اصلاح گرهاي شيميايي در لوله رانش به منظور آناليز كيفي و كمي آن ها و افزايش قدرت تفكيك دستگاه

The separation of isomeric compounds is one of the major challenges in analytical chemistry, an‎d some methods present inherent limitation. In the gas phase, mass spectrometry (MS) is a well-known method for the separation an‎d identification of ions; however, it exhibits limited capability in resolving the isomers. In contrast, ion mobility spectrometry (IMS) has emerged as an effective technique for the separation of gas-phase ions, particularly isomeric species. This method enables ion separation based on differences in mass, charge, an‎d shape through the formation of distinct ionic clusters. The use of chemical modifiers in the drift region enhances isomer separation by promoting the formation of various isomer cluster ions. Furthermore, increasing the resolving power of the instrument plays a crucial role in improving the degree of separation achievable in IMS. In the first study of this thesis, alcoholic modifiers were employed for the separation of dinitrotoluene isomers (2,4 an‎d 2,6). Various parameters, including the electron affinity an‎d dipole moment of the modifiers, as well as the electronic structure of the analytes an‎d their influence on cluster formation, were investigated. Quantitative analysis was ultimately performed using microextraction techniques. The results indicated that the dipole moment of the modifier showed a greater influence on the cluster formation. Moreover, the isomer with higher electronic stability exhibited a lower tendency toward cluster formation. A linear calibration range of 50–700 µg L⁻¹ was obtained, an‎d the relative recovery for dinitrotoluene isomers in real samples was approximately 95%. In the second study, the effects of alcohol-based modifiers an‎d acetonitrile on the separation of nitroaromatic isomers were investigated. The behavior of analyte–modifier clusters in drift tube ion mobility spectrometry was also examined, focusing on the influence of molecular structure, functional groups, an‎d thermodynamic factors. Different degree of clustering clustering were proposed to explain isomer separation, an‎d their stability was eva‎luated through Gibbs free energy (ΔG) an‎d charge transfer calculations. Theoretical results, including collision cross-section (CCS) values an‎d thermodynamic parameters, were compared with experimental data, showing good agreement, particularly in determining the optimal number of modifier molecules required for effective separation. These findings highlight the importance of correlating theoretical an‎d experimental parameters to better understan‎d ion–modifier interactions in the drift region. In the third study, the effects of chiral an‎d achiral modifiers on the separation of carvone enantiomers were investigated, an‎d the experimental conditions were optimized. Among the tested modifiers, tert-butanol exhibited the best performance, providing effective separation of the R- an‎d S-enantiomers. The results indicated that selec‎tivity, ionization behavior, an‎d ion clustering collectively contributed to the enhanced enantiomeric separation. In addition, quantitative analysis of the S-enantiomer was performed using DLLME, yielding a linear range of 0.5–5 μg mL⁻¹ an‎d relative recoveries of 90–100% in real samples. In the fourth study...

محمد تقي جعفري

محمد سراجي , حسين فرخ پور

اكبر ملك پور , عليرضا نجفي چرمهيني , نفيسه فهيمي كاشاني