Ultramark 1621 as a reference compound for positive and negative ion fast-atom bombardment high-resolution mass spectrometry

Ultramark 1621, a commercially available mixture of fluorinated phosphazines, was found to be a useful calibration compound for negative and positive ion fast-atom bombardment (FAB) high-resolution mass spectrometry. Ultramark 1621 worked very well with the most widely used matrices such as glycerol, nitrobenzyl alcohol, and triethanolamine. The negative and positive ion FAB mass spectra of Ultramark include a series of intense peaks extending from 700 to 1900 u.