Chemical ionization of substituted naphthalenes using tetrahydrofuran as a reagent in gas chromatography with ion trap mass spectrometry

Differentiating the aromatic positional isomers of methylbuphedrones and methoxybuphedrones via chemical ionization-mass spectrometry

Discrimination of aromatic positional isomers of methylbuphedrones and methoxybuphedrones was successfully achieved. Meta isomers were discriminated by chemical ionization-tandem mass spectrometry (CI-MS/MS) using acetonitrile as a reagent gas. Furthermore, all the aromatic positional isomers were discriminated by CI-MS/MS using vinyltrimethylsilane as a reagent gas.

Gas chromatographic-ion trap mass spectrometric analysis of volatile organic compounds by ion-molecule reactions using the electron-deficient reagent ion CCl3(+)

When using tetrachloromethane as the reagent gas in gas chromatography-ion trap mass spectrometry equipped with hybrid ionization source, the cation CCl(3)(+) was generated in high abundance and further gas-phase experiments showed that such an electron-deficient reagent ion CCl(3)(+) could undergo interesting ion-molecule reactions with various volatile organic compounds, which not only present some informative gas-phase reactions, but also facilitate qualitative analysis of diverse volatile compounds by providing unique mass spectral data that are characteristic of particular chemical structures. The ion-molecule reactions of the reagent ion CCl(3)(+) with different types of compounds were studied, and results showed that such reactions could give rise to structurally diagnostic ions, such as [M+CCl(3) - HCl](+) for aromatic hydrocarbons, [M - OH](+) for saturated cyclic ether, ketone, and alcoholic compounds, [M - H](+) ion for monoterpenes, M(·+) for sesquiterpenes, [M - CH(3)CO](+) for esters, as well as the further fragment ions. The mechanisms of ion-molecule reactions of aromatic hydrocarbons, aliphatic ketones and alcoholic compounds with the reagent ion CCl(3)(+) were investigated and proposed according to the information provided by MS/MS experiments and theoretical calculations. Then, this method was applied to study volatile organic compounds in Dendranthema indicum var. aromaticum and 20 compounds, including monoterpenes and their oxygen-containing derivatives, aromatic hydrocarbon and sesquiterpenes were identified using such ion-molecule reactions. This study offers a perspective and an alternative tool for the analysis and identification of various volatile compounds.

A simple and rapid method for identifying the source of spilled oil using an electronic nose: confirmation by gas chromatography with mass spectrometry

Two types of electronic nose (EN), different in operational principle, were used to identify the source of spilled oil in an accident. The suspected sources considered were petroleum oil reservoirs and pipelines located near the site of the accident. Gas chromatography/mass spectrometry (GC/MS), operated in both EI and CI modes, was employed to confirm the identified source. The advantage of multisensors in spatially resolved sensing for direct multicomponent analysis was explored to minimize tedious sample preparation procedures. Subsequent principal component analysis helped in identifying the source. The advantage of fast separation in temporally resolved sensing was explored to rapidly yield compositional information; the resulting graphical representations helped clarify the source. Traditional GC/MS not only confirms the identified spilled oil source, but also provides detailed diagnostic information such as total petroleum hydrocarbons, polycyclic aromatic hydrocarbons and their C1-C4 alkylated homologues, as well as the n-alkanes, which are essential for follow-up remedial and regulatory actions. The main use of the electronic nose was demonstrated to be as a simple and rapid screening method for identifying a spilled oil source.