Characterization of cyclotrimethylenetrinitramine (RDX) by pyrolysis H2O/D2O atmospheric-pressure chemical ionization tandem mass spectrometry

The oxidative pyrolysis‐atmospheric‐pressure chemical ionization tandem mass Spectrometry (Py‐APCI MS/MS) of Cyclotrimethylenetrinitramine (RDX) was investigated under various sample introduction conditions. Subambient (0.97 atm) as opposed to ambient (0.98 atm) pressure (1 atm = 101325 kPa) facilitated the appearance of new pyrolysis mass spectral ions, including m/z 44. Deuterated decomposition products from [2H]RDX contained amide groups and, depending on the ion source pressure, significant differences in the degree of proton‐deuterium exchange occurred on the amide groups. The D2O Py‐APCI MS/MS method also confirmed and extended the analogous H2O APCI information from RDX, [2H]RDX and pure standards. The m/z 44 decompositon species was identified as protonated dimethylimine, [H3CNCH2]+ as opposed to its primary amine isomer, [H3CC(H)NH]H+, which contains an acidic proton. It was determined that m/z 60 is due to protonated N‐methylformamide and acetaldoxime, [H3CC(H)NOH]H+.