Calibration substances for negative ion chemical ionization mass spectrometry

The electron capture negative ion spectra of polyperfluoropropylene oxide, high boiling perfluorokerosene, tris(perfluoroheptyl)-s-triazine and perfluorotributylamine were measured under chemical ionization conditions, to evaluate their properties for use as calibration substances. Polyperfluoropropylene oxide (trade name Fomblin) is recommended for such use.