Differential scanning calorimetry screening tests

Where the consequences of combining two or more materials under given conditions of temperature, confinement, etc., are unknown and cannot be predicted with certainty, testing may need to be performed to screen for potential incompatibilities. Two common test methods used for this purpose are differential scanning calorimetry and mixing cell calorimetry (described later in this section). 

Differential Scanning Calorimetry Sample and inert reference materials are heated in such a way that the temperatures are always equal. Onset-of-reaction temperatures reported by the DSC are higher than the true onset temperatures, so the test is mainly a screening test. 

Of course, not all methods of cocrystal production require the use of auxiliary solvents. Thermal microscopy was used to determine if a particular carboxylic acid could cocrystallize with 2-[4-(4-chloro-2-fluorophe-noxy)phenyl]pyrimidine-4-carboxamide, with positive interactions being detected as crystalline material being produced at the binary interface [35]. Once identified, authentic cocrystal systems were prepared on a larger scale using solution-phase methods. In a similar study, hot-state microscopy was used to screen the possible interactions of nicotinamide with seven compounds of pharmaceutical interest that contained carboxylic acid groups [36]. A screening method for cocrystal formation based on differential scanning calorimetry has also been described, and used to demonstrate cocrystal formation in 16 out of 20 tested binary systems [37],... 

Initial Screen. Our initial screen is summarized in Table II. It consists of two test methods, Differential Scanning Calorimetry (DSC) and Differential Thermal Analysis (DTA). In both of these methods the sample is exposed to heat, and thermal changes in the sample are recorded. Heat flow into and out of the sample is recorded in DSC, and the temperature difference between the sample and a reference is recorded in DTA. 

Numerous oxidation tests are available to screen vegetable oil oxidative stability including thin film oxygen uptake test (TFOUT, ASTM D 4/42), rotating bomb oxidation test (RBOT, ASTM D 2272), panel coker test, and pressurized differential scanning calorimetry (Biswas et al., 2007 Erhan et al., 2006 Sharma et al., 2005,... 

It was outlined in chapter 2 in detail that screening tests primarily have the purpose, to provide a first characterization of the safety relevant substance properties as part of the basic assessment. It was further explained that the determination of the thermal stability of a substance is of the greatest importance. The most fi-equently used methods for this puipose are those that investigate thermal stability using very small amounts of sample material only. The most widely used test equipments to perform such investigations are the DTA ( difference thermal analysis ) and DSC ( differential scanning calorimetry). 

Several small-scale screening tests are characterized by the small sample sizes they require (0.01-10 g) and by the speed with which they can be performed. They include differential scanning calorimetry (DSC) and various forms of differential thermal analysis (DTA) the insulated exotherm test (lET), decomposition pressure test (DPT) and the ICI 10 g sealed tube test. Commercial variants of such tests are also available. 

The metathesis activity of these new classes of catalysts has been tested in the solvent-free polymerization of dicyclopentadiene. In a first test we screened their activity in a Differential Scanning Calorimetry (DSC) apparatus and compared it with the activity of the arylthio substituted ruthenium carbene 7 and the "classical" benzylidene catalyst 6. The results are given in Table 8. 

The magnitude of the reaction is an index of the potential of a hazard. The screening tests for the magnitude of a reaction include reaction heat calculation, reaction calorimetry and sealed cell differential scanning scanning calorimetry (SC—DSC). 

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