Hot-stage systems

Several additional considerations should also be noted. Some laboratories may be interested in developing a hot-stage system that possesses the ability to have an overlay of the temperature and the DSC curve on the image from the microscope. 

For this method, either a weighed amount of the solute (or a definite amount of the solvent) is placed in a suitable vessel. While agitating the system at constant temperature, known amounts of the solvent (or the solute) are added gradually until the solubility limit is reached. Appropriate checks must be carried out to ensure that the system is very close to equilibrium when the content or temperature of the system is recorded. In this method of temperature variation, attention is usually focused on the last small crystal. The equilibrium temperature is taken as the mean of the two temperatures at which the crystal either slowly grows or slowly dissolves. This procedure may also be carried out at the microscale by examining a small volume of the system under a hot-stage microscope. 

The nature of the phase formed in the slow coagulation experiment can be deduced on the basis of its thermal transitions, and from its X-ray diffraction pattern. In the DSC trace of the slowly coagulated PBT-MSA-water system shown in Figure 6, three endothermic transitions are observed between 90 °C and 240 °C. Corresponding transitions were observed by optical microscopy using a hot stage. Solid PBT fibers or films do not exhibit thermal transitions below about 650°C (1). 

Temperature-dependent xrd-rsm measurement was performed by employing a dhs 900 domed hot stage (Anton Paar) attached to the PANalytical s X Pert pro-mrd system. Figure 6.8 shows an overview of the dhs 900 domed hot stage. The sample is mounted on... 

Figure 6.8 Anton Paar s DHS 900 domed hot stage attached to the PANalytical s X Pert PRO-MRD system.

To get a better idea of how to formulate the nanosized emulsion delivery systems suitable for parenteral, ocular, percutaneous, and nasal uses, the reader is referred to more detailed descriptions of methods of nanosized emulsion preparation [6, 116], A hot-stage high-pressure homogenization technique or combined emulsification technique (de novo production) is frequently employed in order to prepare nanosized emulsions with desired stability even after subjection to autoclave sterilization. Therefore, the steps involved in this technique in making blank anionic and cationic emulsions were arranged in the following order ... 

Fig. 4.9 (See also color plate section.) Photographs of the microscope shde Kofler preparations showing the various phases of the benzocaine picric acid (BC PA) binary system. Top (a) the photomicrograph of the recrystalhzed contact preparation of BC and PA at 25 °C. The interference colours are due to the use of crossed polarizers. The pure compounds are at the extremities of the preparation, while in the region where the original compounds have merged a number of different areas may be observed, due to the formation of different crystalline species combining the two components. Heating this preparation on the hot stage microscope...

Henrist D, Van Bortel L, Lefebvre RA, Remon JP. In vitro and in vivo evaluation of starch-based hot stage extruded double matrix systems. J Control Release 2001 75 391 00. 

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