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 [ 2 H]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 D 2 O Py‐APCI MS/MS method also confirmed and extended the analogous H 2 O APCI information from RDX, [ 2 H]RDX and pure standards. The m/z 44 decompositon species was identified as protonated dimethylimine, [H 3 CNCH 2 ] + as opposed to its primary amine isomer, [H 3 CC(H)NH]H + , which contains an acidic proton. It was determined that m/z 60 is due to protonated N ‐methylformamide and acetaldoxime, [H 3 CC(H)NOH]H + .