Several procedures for the calibration of MS signals such as m/z= 19 (F+) representing hydrogen fluoride, HF, have been tested in order to achieve a reliable quantitative description of the thermal behaviour of fluorides and/or fluoride hydrates by applying the recent PulseTA((R)) technique (PTA). Instead of desirable indirect calibration methods without the use of the corrosive HF, only the direct injection of 40% aqueous HF gave satisfying results. A differential calibration procedure, recently reported in literature, has been successfully applied. It will be demonstrated that both the calibration of m/z= 18 for water and m/z= 19 for hydrogen fluroride can be performed in a correct way for each mass number. But their joint application to the quantitaive description of a given compound revealed to be difficult if not impossible. This is interpreted in terms of the extreme properties of fluorides simultaneously liberating H2O and HF. (c) 2006 Elsevier B.V. All rights reserved.