DTA—TG—MS in the investigation of clays: Quantitative determination of H2O, CO and CO2 by evolved gas analysis with a mass spectrometer

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.