A thermoanalyzer (Mettler) combined with a quadrupole mass spectrometer (Balzers) by a capillary inlet system allows simultaneous DTA, TG and evolved gas analysis in different atmospheres. Decomposition of CaC2O4·H2O in air and argon, respectively, demonstrates the usefulness of the mass spectrometer for the quantitative determination of H2O, CO2 and CO. Decomposition of NaHCO3 at a heating rate of 10°C min−1 reveals that H2O and CO2 evolved simultaneously at a relatively low temperature (159°C) can also be determined quantitatively and nearly without retardation compared with the weight loss step. In the investigation of clays an example will be given of the usefulness of the described DTA—TG—MS in the quantitative interpretation of overlapping reactions.
