High speed DSC

Another important technique is the thermal analysis technique of differential scanning calorimetry (DSC). Current high-speed DSC equipment (sometimes also referred to as hyper-DSC) allows for rapid heating (up to 500°C/min) and cooling of (small) samples and therefore an increased rate of analysis per sample... 

Saunders, M. Podluii, K. Shargill, S. Buckton, G. Royall, P. The potential of high speed DSC (Hyper-DSC) for the detection and quantification of small amounts of amorphous content in predominantly crystalline samples. Int. J. Pharm 2004, 274, 35-40. 

Temperature modulated DSC (MDSC)2°2-204 jg another technique that has proved useful in the study of the glass transition " - where, it has been claimed, the approach is capable of providing better resolution and sensitivity than conventional DSC.2° In this, a modulated temperature programme is superimposed upon the conventional heating ramp and the resulting heat flows are interpreted in terms of two heat capacities an in-phase storage heat capacity and an out-of-phase kinetic heat capacity. Various theoretical procedures have been proposed for this and there is little doubt that the approach can provide information that is complementary to conventional DSC.2 ° However, the technique does involve slow temperature scans (cf. high-speed DSC above) and the authors feel that there are areas where the additional data are not, at present, easy to interpret. 

Sichina WJ. High sensitivity characterization of transparency films using high speed DSC. 

Gabbott P, Clarke P, Mann T, RoyaU P, ShergiU S. A high-sensitivity, high-speed DSC technique measurement of amorphous lactose. Am Lab 2003, reprint from PerkinElmer. 

Gramaglia D, Conway BR, Kett VL, Malcolm RK, Batchelor HK. High speed DSC (HyperDSC ) as a tool to measure the solubflity of a drug within a soUd or semi-solid matrix. Int J Pharm 2005 301 1 5. 

The versatility of the DSC method and the high speed of the experiments have costs in terms of accuracy. For example, the best accuracy in the determination of heat capacities of solids by DSC is typically 1% [3,248-250], at least one order of magnitude worse than the accuracy of the corresponding measurements by adiabatic calorimetry [251]. This accuracy loss may, however, be acceptable for many purposes, because DSC experiments are much faster and require much smaller samples than adiabatic calorimetry experiments. In addition, they can be performed at temperatures significantly above ambient, which are outside the normal operating range of most adiabatic calorimeters. 

McGregor, C. Saunders, M.H. Buckton, G. Saklatvala, R.D. The use of high-speed differential scanning calorimetry (Hyper-DSC ) to study the thermal properties of carbamazepine polymorphs. Thermochim. Acta 2004, 417, 231-237. 

FIGURE 8 Hi speed DSC profile of carbamazepine Form 111, showing that at high scanning speeds the melting endotherm of F[Pg.418]

Figure 4. The present evolution of Standard DSC towards a range of low- to high-speed calorimeters [32]. Commercial instruments like heat-flux and power-compensation Standard DSCs work typically at scan rates of 0.1 to 60 C/min High Performance DSC (HPer DSC), using a modified PerkinElmer power-compensation Pyris 1 or Diamond DSC, covers the range 0.1 to 500 C/min thin-film (chip) calorimeters have scan rates from 1000 to 1.2-10 C/min and rates as high as 6-10 C/min are attainable using the high-speed pulse-calorimeter (all numbers are approximate indications).

A fast measurement takes minimal time, and instrumental drift can be negligible. Thus, in principle, it is possible to work quantitatively even at high rates, which is why the name High Performance DSC has been coined. HPer DSC provides more than just the ability to make measurements at high speeds. The examples in [29] show that heat capacity measurements at rates as high as 100 C/min are achievable. 

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. 

A more recent step to speed up DSC was taken in connection with a commercial power-compensation DSC (High Performance DSC) [6] and is now available as HyperDSC from the Perkin-Elmer Inc. It is claimed to reach 500 K min. For a pan of a diameter of 5 mm, the heating rates calculated in Fig. A. 10.1 corresponds to sample masses of 20, 2, and 0.2 mg, showing that it is the heating and cooling capacity of the DSC that limits fast calorimetry, not the properties of the sample. 

Vanden Poel, G. and Mathot, V.B.F. (2006) High-speed/high performance differential scanning calorimetry (HPer DSC) Temperature calibration in the heating and cooling mode and minimization of thermal lag. Thermochim. Acta, 446,... 

Vadim P. Zakharov, DSc, is Professor and Vice-Chancellor for Scientific Work at Bashkir State University in Ufa, Russia. He is a Laureate of the Russian Government Award in Science and Technology. He has trained five candidates of science (PhD) and is author and co-author of three monographs, more than 160 scientific articles, and 11 patents. His area of expertise is in macrokinetics of high-speed processes in liquid phase and catalytic polymerization of dienes. 

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