負イオン化学イオン化質量分析法における低質量域校正用標準物質の検討

抄録

The mass calibration standard materials in the low mass region for negative ion chemical ionization (NCI) mode in a magnetic sector mass spectrometer were sought, because perfluorokerosine (PFK) and perfluorotributylamine (PFTBA) used in EI mode scarcely produce negative ions below m/z 200. The 45 fluorine-containing compounds (5 alkanes, 6 ketones, 5 esters, 5 ethers, and 3 acid anhydrides, etc.) were tested, and the 10 : 1 : 1 mixture of 3 esters [CF₃COOCH₃, C₂F₅COOC₂H₅, C₃F₇COOC₂H₅] and the 1 : 1 : 1 mixture of 3 acid anhydrides [(CF₃CO)₂O, (C₂F₅CO)₂O, (C₃F₇CO)₂O] were found to be advantageous. In their NCI mass spectra, ions were observed at m/z 69, 85, 113, 128, 144, 178, 194, and m/z 113, 128, 144, 163, 178, and 194, respectively, with the relative ion intensities of several to 100%. The standard materials for mass calibration and for selected ion monitoring were also purposed.