Chemical ionization (CI) is commonly used with gas chromatography mass spectrometry (GC-MS) to confirm the molecular weight of compounds. Although EI, electron ionization, is a primary method and generates unique fragmentations which help to identify compounds, this typically causes a loss in molecular weight information. CI compensates this missing point. However, CI requires a compressed flammable gas cylinder, such as methane and isobutane. These kinds of gases are expensive and not allowed in some laboratories due to their safety policy. To address these situations, Shimadzu has developed new chemical ionization technique using organic solvent which is being called solvent mediated chemical ionization (SMCI).
In this study, the mechanism of this new technique and its use in unknown compound data will be presented.