Sigman Michael E, Armstrong Paul A, Macinnis Jean M, Williams Mary R
National Center for Forensic Science and Department of Chemistry, University of Central Florida, Orlando, 32826, USA.
Anal Chem. 2005 Nov 15;77(22):7434-41. doi: 10.1021/ac058037v.
An equilibrium partitioning model is applied for the first time to the sequential formation of 1:1 and then 2:1 adducts between the high explosive cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) and halide anions fluoride, chloride, bromide, and iodide in electrospray ionization interface (ESI) mass spectrometry. The equilibrium partitioning model is developed and model calculations are presented to demonstrate the generic behavior of the system, which is in qualitative agreement with the observed changes in 1:1 (RDX-halide) and 2:1 (RDX-halide) responses in ESI-MS. The model is successfully applied to the experimental data with the use of octanol-water partitioning coefficients to predict interior-to-surface partitioning behavior of the complexes in droplets formed in the ESI. The data and model suggest that the significantly more hydrophobic 2:1 complexes are readily observed in ESI-MS, even though their formation constants may be several orders of magnitude less than that of the 1:1 complex. Structures for RDX-halide 1:1 and 2:1 complexes are proposed based on ion-dipole attractions and destabilizing dipole-dipole interactions.
一种平衡分配模型首次应用于高爆炸药环三亚甲基三硝胺（RDX）与卤化物阴离子氟化物、氯化物、溴化物和碘化物在电喷雾电离界面（ESI）质谱中依次形成1:1和2:1加合物的过程。开发了平衡分配模型并进行了模型计算，以证明该系统的一般行为，这与ESI-MS中观察到的1:1（RDX-卤化物）和2:1（RDX-卤化物）响应的变化在定性上是一致的。该模型通过使用辛醇-水分配系数成功应用于实验数据，以预测ESI中形成的液滴中配合物的内部到表面的分配行为。数据和模型表明，在ESI-MS中很容易观察到疏水性明显更强的2:1配合物，尽管它们的形成常数可能比1:1配合物的形成常数小几个数量级。基于离子-偶极吸引力和不稳定的偶极-偶极相互作用，提出了RDX-卤化物1:1和2:1配合物的结构。
