Son Chae Eun, Choi Sung-Seen
Department of Chemistry, Sejong University, Seoul, Republic of Korea.
Rapid Commun Mass Spectrom. 2023 Feb 15;37(3):e9434. doi: 10.1002/rcm.9434.
Trinitrotoluene (TNT) and its derivatives are found in the environment. Depending on the analysis conditions, TNT may be detected as a deprotonated molecule or a molecular ion through atmospheric pressure chemical ionization (APCI). Dichloromethane (CH Cl ) is used as an extraction solvent for TNT from environmental samples and as an ionizing agent to generate chlorinated species. APCI mass spectra of TNT dissolved in CH Cl revealed the presence of only the [TNT - H] ion. This phenomenon was investigated by reactions with the CH Cl -related reactant ions.
TNT in CH Cl was ionized through APCI, and CH Cl and acetone were used as the eluent. The vaporizing temperature was varied from 200 to 350°C. TNT-related ions and reactant ions were analyzed. Detection limits for TNT were determined under different conditions. Energy-minimized structures of the product ions were used to interpret the analysis results.
Significant [TNT - H] ion was observed, but the [TNT + Cl] and TNT ions were not detected. The [HCl + Cl] and [3acetone + Cl] ions were detected as reactant ions when using CH Cl and acetone as eluent, respectively. Other potential reactant ions such as CH Cl and [CH Cl + Cl] were not observed. The detection limit improved as the vaporizing temperature increased. The favorability of [TNT - H] formation was explained on the basis of the heats of reactions.
The [TNT - H] ion was primarily produced by the deprotonation reaction between CH Cl and neutral TNT. This reaction was determined to be significantly exothermic. CH Cl can be helpful for the analysis of TNT in environmental samples through APCI mass spectrometry.
三硝基甲苯（TNT）及其衍生物存在于环境中。根据分析条件，通过大气压化学电离（APCI），TNT可能被检测为去质子化分子或分子离子。二氯甲烷（CH₂Cl₂）用作从环境样品中萃取TNT的溶剂以及用于生成氯化物种的电离剂。溶解于CH₂Cl₂中的TNT的APCI质谱显示仅存在[TNT - H]离子。通过与CH₂Cl₂相关的反应离子进行反应来研究此现象。
通过APCI使CH₂Cl₂中的TNT电离，使用CH₂Cl₂和丙酮作为洗脱剂。蒸发温度在200至350°C之间变化。分析了与TNT相关的离子和反应离子。在不同条件下测定了TNT的检测限。使用产物离子的能量最小化结构来解释分析结果。
观察到显著的[TNT - H]离子，但未检测到[TNT + Cl]和TNT离子。当分别使用CH₂Cl₂和丙酮作为洗脱剂时，检测到[HCl + Cl]和[3丙酮 + Cl]离子作为反应离子。未观察到其他潜在的反应离子，如CH₂Cl₂⁺和[CH₂Cl₂ + Cl]。检测限随着蒸发温度的升高而提高。基于反应热解释了[TNT - H]形成的有利性。
[TNT - H]离子主要由CH₂Cl₂与中性TNT之间的去质子化反应产生。该反应被确定为显著放热。CH₂Cl₂有助于通过APCI质谱分析环境样品中的TNT。
