CI Mass Spectra of Intact Labile Compounds by Solution Sample Introduction Method

Abstract

Organic labile compounds such as nucleic acids, amino acids, catechol amines and mono-, di-saccharides dissolved in an appropriate solvent, were introduced together with solvent into the Cl ion source held at 130°C of a Finnigan 3300 E GC/QMS through a simple interface. The interface consists of an internal capillary stainless steel tube in which the 1μg/μl sample solution and solvent are passed through by a micro LC pump at a flow rate of 2 μl/min, and also an external one which passes methane. Methane was introduced to aid sample introduction in aerosol form to assure stable ionization. In some cases an ammonia water reservoir was located on another line. Solvent-methane mixture was applied as reagent gas and (S+H)+ from solvent(S) possessing the highest proton affinity was the dominant ion which acted as reactant ion as reported in our previous paper. Consequently significant CI mass spectra were readily obtained without derivatization, and especially noteworthy was that ammonia-containing reagent gas produced peaks showing molecular weight information.