Thermal analysis methods, summary

Most workers in the pharmaceutical field identify thermal analysis with the melting point, DTA, DSC, and TG methods just described. Growing in interest are other techniques available for the characterization of solid materials, each of which can be particularly useful to deduce certain types of information. Although it is beyond the scope of this chapter to delve into each type of methodology in great detail, it is worth providing short summaries of these. As in all thermal analysis techniques, the observed parameter of interest is obtained as a function of temperature, while the sample is heated at an accurately controlled rate. 

A summary of current kinetic methods used with thermal analysis techniques can be found in Ref. l... 

For this summary, forms of thermal analyses under extreme conditions are described for the measurement of heat and temperature, as dealt within Sects. 4.1-4. The distinction between DTA and DSC seen in these methods is described in Appendix 9. In Appendix 10, DTA or DSC at very low and high temperatures and DTA at very high pressures are mentioned. This is followed by a discussion of high-speed thermal analysis which, in some cases, may simply be thermometry. Finally, micro-calorimetry is treated. One might expect that these techniques will develop in this century [1]. The numbers in brackets link to references at the end of this appendix. 

In summary, high pressure liquid chromatography can be used not only in the analysis of nucleotides, but in the analysis of almost any biologically active compound. It is especially useful for the separation of those thermally-labile, non-volatile, polar cell components and drugs that are difficult to measure by other methods (14). In addition, drugs and their metabolites can be monitored concurrently with the effects of these drugs on the naturally occurring cell constituents. Therefore, this instrument is a valuable addition to any well equipped biomedical laboratory for use by itself or in combination with other available techniques. 

Potency analysis of the amorphous dispersion systems revealed that drug recovery was significantly higher with KinetiSol versus HME for comparable process feeds. In the case of Eudragit LlOO-55, the mean ROA potency value was 70.9 % for KinetiSol and 22.7 % for HME. The mean potency value for the HPMCAS-LF composition was 99.4 % with KinetiSol and 70.9 % for HME. A comparative summary of processing parameters and chemical analysis of the KinetiSol and HME products is provided in Table 18.1. The results demonstrated that KinetiSol was an effective method for producing ASDs where HME was not feasible, owing to the compound s thermal instability. 

In summary, the simplified inelastic analysis rules as indicated in subsections NB 3327.6 and NB 3228.3 of the ASME Boiler and Pressure Vessel Code Section III have been critically appraised. The first rule is shown to be equivalent to a correction factor, K, to be applied to local thermal stresses, and is based on an analysis involving a modified Poisson s ratio. For a simplified situation of thermal stress in a plate with a through the thickness temperature gradient (perfect biaxiality) the solution using NB 3227.6 are comparable to the existing solutions in the literature. However, the solutions obtained using finite-element methods and a different form of Poisson s ratio than that specified in NB 3227.6 (Eq. (11.1)) typically yield higher values of K. ... 

---