Identification of related compounds by GC-MS

Identification of Related Substances Using GC-MS Thesis Jaroslav Kušnír Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Chemistry and Drug Control A molecular weight was researched for the purpose of identifying three foreign matters, which were found in 1,3-butanediol substance during GC/FID. GC/MS technique was used for researching molecular weight. Following techniques were used to ionize the samples - electron ionization, chemical ionization using methane and isobutene reagent gases. To acquire a more stable molecular ion, different derivative reactions were tried as for example acylation. Nevertheless result were not satisfiable. Chemical ionization using isobutene reagent gas was found to be the most effective for researching molecular weight of the foreign matters. Isobutene is more sensitive reagent gas than methane and therefore a more intensive ion (M+H)+ can be found in the mass spectrum, from which it is possible to define molecular weight. Apart from researching molecular foreign matters, the best conditions for using reagent gas isobutene in GC/MS were examined. From the measuring it was found that the best conditions are during 80 kPa pressure and increased voltage by 0.4 kV from the default setting of the detector. Molecular weight of..