Andre Marois

Synthesis of 14C-labelled octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) for use in microcosm experiments

To monitor the biodegradation of explosives in microcosm experiments, carbon-14 labelled substrates such as 14C-HMX were needed. Many synthetic routes were evaluated to identify the best synthesis of 14C-HMX with high yield and minimal radioactive waste. To synthesize 14C-HMX, acetylation of labelled hexamethylenetetramine (14C-HMTA) was done yielding 3,7-diacetyl-1,3,5,7-tetraazabicyclo-[3.3.1]-nonane (14C-DAPT) which was nitrated to obtain 1,5-diacetyloctahydro-3,7-dinitro-1,3,5,7-tetrazocine (14C-DADN) in one step. Nitrolysis of 14C-DADN was achieved using a mixture of 100% nitric acid and phosphorus pentoxide to yield 14C-HMX. The synthesis of this carbon-14 labelled HMX was optimized first using cold starting materials and then conducted with labelled compounds. This synthesis represents the best way of preparing high purity 14C-HMX with a high yield. Copyright

Overestimation of nitrate and nitrite concentrations in water samples due to the presence of nitroglycerin or hexahydro-1,3,5-trinitro-1,3,5-triazine

A large number of laboratory studies have reported nitrite (NO(2)(-)) and nitrate (NO(3)(-)) to be among the most common degradation products of the high explosives nitroglycerin (NG) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Additionally, several field studies have reported the presence of RDX or NG along with NO(3)(-) in groundwater near production plants. Most studies, however, did not specify whether their NO(2)(-) and NO(3)(-) analyses were performed on samples which also contained RDX or NG. Inconsistent NO(2)(-)/NO(3)(-) results obtained in our laboratory suggested that the presence of RDX or NG in water samples caused an overestimation of NO(2)(-) and NO(3)(-) concentrations when using two of the most common analytical methods, namely ionic chromatography and automated colorimetry. This could have important implications for mass balance calculations and for environmental decisions. This paper focused on quantifying the overestimation of NO(2)(-)/NO(3)(-) due to the presence of RDX and NG, and finding a method for extracting RDX and NG from water samples without affecting NO(2)(-)/NO(3)(-). Results showed that the overestimation can be predicted using regression coefficients; however the margin of error at the 95% confidence level was between 5 and 15%. Alternatively, a cartridge was found which retains both RDX and NG without affecting NO(2)(-)/NO(3)(-). The cartridge can be used for concentrating the RDX or NG in dilute environmental samples, while removing RDX/NG from solution to allow the interference-free analysis of NO(2)(-)/NO(3)(-). Additionally, if recovery of RDX/NG from the cartridges is not desired, the cartridges could be used for the extraction of more than one sample, thus reducing the costs.