Differential scanning calorimeters calibration

The thermal behavior of pantoprazole sodium was examined by DSC, using a TA Instrument model 91 OS differential scanning calorimeter calibrated with indium. Pantoprazole sodium samples ranging from 5 to 10 mg were run at a heating rate of 5°C/min over a temperature range of 50°C to 179°C. 

Thermal Properties. The glass transition temperature (Tg) and the decomposition temperature (Td) were measured with a DuPont 910 Differential Scanning Calorimeter (DSC) calibrated with indium. The standard heating rate for all polymers was 10 °C/min. Thermogravimetric analysis (TGA) was performed on a DuPont 951 Thermogravimetric Analyzer at a heating rate of 20 °C/min. 

Glass transition temperatures of the uv-hardened films were measured with a Perkin Elmer Model DSC-4 differential scanning calorimeter (DSC) that was calibrated with an indium standard. The films were scraped from silicon substrates and placed in DSC sample pans. Temperature scans were run from -40 to 100-200 °C at a rate of 20 ° C/min and the temperature at the midpoint of the transition was assigned to Tg. 

The heat flux and energy calibrations are usually performed using electrically generated heat or reference substances with well-established heat capacities (in the case of k ) or enthalpies of phase transition (in the case of kg). Because kd, and kg are complex and generally unknown functions of various parameters, such as the heating rate, the calibration experiment should be as similar as possible to the main experiment. Very detailed recommendations for a correct calibration of differential scanning calorimeters in terms of heat flow and energy have been published in the literature [254,258-260,269]. 

G. W. H. Holme, H. K. Cammenga, W. Eysel, E. Gmelin, W. Hemminger. The Temperature Calibration of Differential Scanning Calorimeters. Thermochim. Acta 1990, 160, 1-12. 

E. Gmelin, S. M. Sarge. Calibration of Differential Scanning Calorimeters. Pure Appl. Chem. 1995, 67, 1789-1800. 

ASTM E 967-92, Standard Practice for Temperature Calibration of Differential Scanning Calorimeters and Differential Thermal Analyzers, 1992. 

ASTM E 968-83, Standard Practice for Heat Flow Calibration of Differential Scanning Calorimeters, 1983. 

Glass transition temperatures were measured using a Peikin-Elmer Differential Scanning Calorimeter, Model DSC-IB. Heating rate was at 10°/min. Accuracy was about 5°. The instrument was calibrated by using alkanes of various melting points. 

As has been shown in this chapter, the differential scanning calorimeter and microcalorimeters have been shown to have wide applications in all aspects of pharmaceutical sciences, such as in preformulation and formulation development. However, the utility of these instruments is only possible with careful attention to following established calibration procedures. The DSC and other calorimeters are a critical part of a pharmaceutical scientists armamentarium. 

Price, D.M. Temperature calibration of differential scanning calorimeters. J. Therm. Anal. 1995, 45, 1285-1296. 

Skoglund, P. Fransson, A. Accurate temperature calibration of differential scanning calorimeters. Thermochim. Acta 1996, 276, 27-39. 

Sarge, S.M. Gmelin, E. Temperature, heat and heat flow rate calibration of differential scanning calorimeters. Thermochrm. Acta 2000, 347, 9-13. 

Heat capacities were determined by using a differential scanning calorimeter (DSC). A sapphire standard was used for DSC cell calibration. Samples were cut directly from the samples used in the thermal diffusivity measurements. Heat capacity was determined, as usual, from the heat requirement of the sample in response to a particular change in temperature. Multiple scans were performed to verify that sample degradation did not influence the results. Char samples could be heated up to 850 K in these experiments. The DSC cell was continuously purged with nitrogen, in order to avoid oxidation of the samples. 

Thermal analyses of the polymer samples were conducted on a Perkln-Elmer DSC-IB Differential Scanning Calorimeter. Approximately 1 mg of sample was used in each determination. The heating rate employed was 16°C/mln. The instrument was calibrated using indium as a standard. 

A standard procedure for the temperature calibration of differential thermal analysers and differential scanning calorimeters has been published as ASTM E 967 (1999). In the two point method two calibrants are chosen to bracket the temperature range of interest. It is assumed that the correct temperature T is related to the experimental temperature Texp by the relationship,... 

E 967 (1999) Standard practice for temperature calibration of differential scanning calorimeters and differential thermal analyzers... 

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