Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI), 402 North Blackford Street, LD326, Indianapolis, IN, 46202, USA.
Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI), 402 North Blackford Street, LD326, Indianapolis, IN, 46202, USA; Forensic and Investigative Sciences Program, Indiana University-Purdue University Indianapolis (IUPUI), 402 North Blackford Street, LD326, Indianapolis, IN, 46202, USA.
Anal Chim Acta. 2021 Jan 25;1143:117-123. doi: 10.1016/j.aca.2020.11.041. Epub 2020 Nov 30.
Gas chromatography/vacuum UV spectroscopy (GC/VUV) was utilized to study various explosives and pharmaceuticals in the nitrate ester and nitramine structural classes. In addition to generating specific VUV spectra for each compound, VUV was used to indicate the onset of thermal decomposition based upon the appearance of break-down products such as nitric oxide, carbon monoxide, formaldehyde, water, and molecular oxygen. The effect of temperature on decomposition could be fit to a logistical function where the fraction of intact compound remaining decreased as the transfer line/flow cell temperature was increased from 200 °C to 300 °C. Utilizing this relationship, the decomposition temperatures for the nitrate ester and nitramine compounds were determined to range between 244 °C and 277 °C. It was also discovered that the decomposition temperature was dependent on the GC carrier gas flow rate and, therefore, the residence time of the compounds in the transfer line/flow cell. For example, the measured decomposition temperature of nitroglycerine ranged from 222 °C to 253 °C across four flow rates. Tracking the appearance/disappearance of decomposition products across this temperature range indicated that NO, CO, and HCO are final decomposition products while O and HO are intermediate products. The decomposition temperatures for all explosives were highly correlated to similar decomposition measurements taken by differential scanning calorimetry (DSC) (r = 0.91) and thermal gravimetric analysis (TGA) (r = 0.90-0.98). In addition, the decomposition temperatures for all explosives were negatively correlated to the heat of explosion at constant volume (r = -0.68) and strongly positively correlated to the oxygen balance (r = 0.92).
气相色谱/真空紫外光谱（GC/VUV）被用于研究硝酸盐酯和硝胺结构类别的各种爆炸物和药物。除了为每个化合物生成特定的 VUV 光谱外，VUV 还可用于根据热分解产物（如一氧化氮、一氧化碳、甲醛、水和分子氧）的出现来指示热分解的开始。温度对分解的影响可以拟合到逻辑函数中，其中未分解化合物的分数随着传输线/流动池温度从 200°C 增加到 300°C 而降低。利用这种关系，确定硝酸盐酯和硝胺化合物的分解温度范围在 244°C 至 277°C 之间。还发现分解温度取决于 GC 载气流速，因此化合物在传输线/流动池中的停留时间。例如，在四个流速下，甘油三硝酸酯的测量分解温度范围在 222°C 至 253°C 之间。在这个温度范围内跟踪分解产物的出现/消失表明，NO、CO 和 HCO 是最终的分解产物，而 O 和 HO 是中间产物。所有爆炸物的分解温度与差示扫描量热法（DSC）（r = 0.91）和热重分析（TGA）（r = 0.90-0.98）进行的类似分解测量高度相关。此外，所有爆炸物的分解温度与定容爆炸热（r = -0.68）呈负相关，与氧平衡呈强正相关（r = 0.92）。
