As a result, the intensity of ([TNT+H] -, m/z 228), the hydride adduct ion for TNT, is somewhat higher than that of ([TNT+NO3-HNO2] -, m/z 242). Although the vapor pressure of TNT is fairly high (~10 -4 Torr at 20 °C), the surface-assisted reduction reaction may also cause a tiny fraction of TNT molecules to have a longer relaxation period, resulting in the hydride ion, ([TNT+H] -, m/z 228), appearing later in the TIC.