Trace gas analysis using thermoanalytical methods

Summary

At present, there is an increasing demand for trace gas analytical information, especially in several fields of environmental protection, such as protection of workers from exposure to hazardous substances in work place atmospheres, ambient and indoor air pollution, or gaseous exhalations from polluted soils, waters, or waste deposits. Though the existing powerful trace analytical tools are in principle capable of answering the questions related to these problems, they cannot satisfy the information demand. This is mainly due to the fact that most of these analytical tools are to be used in the course of rather sophisticated multistep procedures which are time consuming and claim high personnel qualification and, thus, are too expensive for large scale application. This difficulty can be overcome by the development of simple one-step procedures based on low price ready-for-use sampling units which can be processed with a minimum of manpower input and, in addition, provide information of the required reliability. One possible way to this goal may be based on the measurement of caloric effects associated with the decomposition of the products resulting during the sampling step from a gas-solid reaction between the traces to be analyzed and suitable solid state reagents. Starting from properly prepared text gas mixtures, the gas-solid reactions of numerous amines, alcohols, aldehydes, ketones, hydrocarbons and halogenated hydrocarbons with several metal complexes and with reagents capable of forming clathrates have been investigated by means of thermoanalytical methods, mainly by means of differential scanning calorimetry (DSC). The results show that in many cases the very simple thermoanalytical evaluation enables both qualitative identification and quantification of the gas traces under concern with satisfying selectivity. These reaction may serve, therefore, as a promising basis for further development of fast, simple and reliable trace gas analysis using thermoanalytical methods.