2,2,4,4,6,6-Hexakis[(2,2,3,3,4,4,5,5-octafluoropentyl)oxy]-2λ5,4λ5,6λ5-1,3,5,2,4,6-triazatriphosphorine is a component of Ultramark 1621 which is a useful calibration compound for negative and positive ion fast-atom bombardment (FAB) high-resolution mass spectrometry.