Simultaneous determination of multiple components in explosives using ultraviolet spectrophotometry and a partial least squares method

The quantitative analysis of explosives is very important for national defence and security inspection. However, conventional analytical methods are complicated and time-consuming because of the complexity of the explosive samples. Herein, we proposed a new quantitative method, which combined ultraviolet (UV) spectrophotometry with partial least squares regression (PLS-1 and PLS-2), to quickly determine the content of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclo-octane (HMX), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT) simultaneously from mixed explosive samples. The calibration models were constructed by using 49 reference samples in the calibration set and optimized by full cross-validation. The predictive performance of the optimized models was validated by 21 explosive samples in an independent test set. The standard errors of prediction (SEP) were lower than 1.4 μg mL−1 for HMX, 2.2 μg mL−1 for RDX, and 0.8 μg mL−1 for TNT in both PLS models. Finally, the optimized PLS-1 and PLS-2 models were successfully applied to simultaneously determine the three explosive ingredients in eight polymer bonded explosives (PBXs). The average recovery was close to 100% for each of the three components. Thus, UV spectrophotometry combined with PLS regression can be considered as a promising strategy to conduct the determination of HMX, RDX and TNT in practice.