Sample mass large

High sample throughput with little sample manipulation and possibility of treating large sample masses (hence, lesser problems with inhomogeneity). 

A comparison between the DSC method (using the Perkin-Elmer DSC-1B instrument) and the premelting method of Johnston and Giauque (51) is shown in Table 10.3 (52). Johnston and Giauque (51) came to the conclusion that the nitric oxide used in their measurements contained less than 10"3 mole-% of eutectic impurities, or the so-called purity is of the order of 99.999%. The authors excluded the possibility of noneutectic impurities. It should be noted that the difference between the two methods is not in thermodynamics but rather in instrumentation and the properties of the methods of measurement. The disadvantage of the calorimetric method is the extremely long measurement time of 2-4 days, which is due to the large sample masses and the necessity for equilibrium to be attained at each temperature. The penalty for a shorter analysis time is, of course, a lower accuracy in purity measurements. 

Arias et al. [45] attributed the surprising discrepancy between their results and the ones reported by Manovic and Anthony [43] to the different experimental setup employed, i.e. Manovic and Anthony s [43] results were obtained in a TGA, which does not operate under differential conditions. In such an experimental setup, further factors, such as external diffusion owing to the large sample mass used (30 mg vs. <3 mg in the experiments by Arias et al. [45]) and internal diffusion in the large sorbent particles, may affect the results. 

These energetic photons, like neutrons, are capable of penetrating into thick solid samples. This allows bulk analysis without chemical pretreatment. A drawback of this method is the large sample mass required. 

In cases where TA apparatus is used in special conditions, such as at high pressure (above 10 MPa), high temperature (above 1700 C) and a large sample mass (above several grams), it is necessary for users to assemble the apparatus themselves. 

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