Thermal analysis gaseous nitrogen

For a sample mass of approximately 2-10 mg a gas flow rate of 15-25 ml/min is recommended. Maintaining a constant flow is important especially in the thermal analysis of gaseous compounds (the case of thermal decomposition), because it will provide a stable partial pressure of the products [21]. Most analyses are made in nitrogen atmosphere [12, 19, 28-30] or air [7, 9, 31-33], and sometimes in argon atmosphere [7, 33] or carbon dioxide [7]. 

A detailed analysis of the products of thermal destruction of poly-hexamethyleneadipamide and polycaproamide is given in [22]. The polyamides were heated at 300-305°C in a stream of dry nitrogen. The gaseous pyrolysis products contain large amounts of NH3, CO2, H2O, small amounts of n-hexylamine, n-pentylamine, and cyclopentanone. Analysis of the hydrolysis products of the residue obtained after pyrolysis of the polyamides permitted the authors to propose a scheme for the process. 

The differential distillation technique (also known as subambient thermal volatilization analysis (SATSVA) is a very simple technique which allows a rapid indication (both qualitative and quantitative) of small amounts of gaseous and/or liquid low molecular weight compounds which can be trapped and frozen at liquid nitrogen temperature [1439, 1440]. 

It is possible to analyze approximately 40 elements by thermal ionization mass spectrometry and another ten elements by electron impact (including gaseous compounds of elements such as nitrogen, oxygen, carbon, and silicon). When isotope dilution is applicable, it usually is by far the most accurate method for the determination of impurities and traces. The leverage for precision and accuracy comes from the limited number of quantitative steps necessary for the analysis. 

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