TG-MS ? Quantitative analysis ? Evolved gases ? Thermal decomposition ? Ammonium salts ? Mechanism

The quantitative TG-MS method was used for the detection and quantification of gases evolved during the thermal decomposition of ammonium salts. The validity of the method was confirmed in the decomposition of NH4CO3 and NH4Cl, compounds with a simple decomposition route. A validated TG-MS approach was used to find out the decomposition mechanism of (NH4)(2)SO4 and NH4NO3. In the case of ammonium sulphate, besides expectable H2O, NH3 and SO2, the evolution of elemental N-2 and O-2 was also confirmed. The ammonium nitrate decomposition mechanism significantly depended on the mass of the sample, and the expected evolution of N2O was pronounced with increasing sample mass. On the other hand, with the lower sample mass, the evolution of N-2 and NO gases predominate over the N2O gaseous product. In general, it was confirmed that the quantitative TG-MS method provides a simple way of analysis of gaseous mixtures and can bring new insight into the decomposition mechanism of inorganic salts.