The ions generated by the HCD ion source for the explosives of interest were monitored using a linear ion trap mass spectrometer by altering the experimental settings as follows: 150-200 °C for ion transport tube; 80% for S-lens and 600-800 V for RF ion guide voltage. With a maximum ion injection time of 2 ms and a number of micro scans of 1, auto gain control was enabled. The ions produced by the explosive compounds were characterized using tandem mass spectrometry (MS/MS). When helium was employed for collision, the collision-induced dissociation (CID) mode was used, with the collision energy ranging from 20 to 50% .