was reported . Because the air pressure is reduced by the counter-flow introduction sampling method, the presence of NOx is reduced to a minimum, preventing the proton abstract reaction from the TNT molecules. Because of TNT's strong electron affinity (2.5 eV), the electron attachment reaction takes precedence and the molecular ion emerges as a major ion . Formation of TNT molecular ion, ([TNT] -• , m/z 227) was also observed by using the direct analysis in real time (DART) ion source . This is because helium plasma in the DART holds high electron density rather than NOx that facilitates the electron attachment reaction. Electrospray-based techniques have also been used and found the molecular ion, ([TNT] -• , m/z 227) is the major ion . The DBD ion source, on the other hand, produced ([TNT-H] -, m/z 226) as a major ion and ([TNT] -• , m/z 227) as a minor ion . As a result, it is argued that air-excited plasma produces ([TNT-H] -, m/z 226) and/or ([TNB-H] -, m/z 212) ions, whereas solely helium plasma promotes electron attachment processes that produce the molecular ion. To put it another way, as the plasma gas is contaminated by air, the relative intensity of [M-H] -rises . , [TNB] -• , and [TNB+H] -, which have m/z 212, 213, and 214, respectively (Fig. ). The ions with the m/z 212, 213, on the other hand, came from the m/z 242 ion as fragment ions, as indicated in the inset in Fig. (a) . TNT ions with m/z 212, 211, and 213 appeared as minor ions (Fig. ), whereas 2ADNT and 4ADNT ions appeared as major ions (Fig. ). The formation of adduct ions of the 2ADNT and/or 4ADNT is thought to be responsible for the m/z 212 ion, which has been designated as [ADNT+NO3-HNO2] -, m/z 212).