Microscopic sample preparation, drug

Optical microscopy and scanning electron microscopy (SEM) were used to evaluate the drug incorporation and surface shape of the microspheres prepared under the various conditions. Particle size was determined using a Tiyoda microscope. Samples of microspheres (180-200) were dispersed on a slide and their diameter was then sized using suitable objectives. 

The sampling preparation techniques for IR determination are solution, drug dispersion in a KBr pellet, Nujol mulls, and direct determination by microscopic ATR preparation. An example of modern IR equipment is FTIR, which gives better quality determination. Unlike conventional IR (using a dispersed system with a slowly moving mirror to measure each frequency individually), FTIR uses a simple optical device, an interferometer that allows the simultaneous measurement of frequency. Because there are no mechanical movements involved, the determination is rapid. The frequency is calculated with the well-known mathematical technique called Fourier transformation. 

The optical microscope is a valuable tool in the laboratory and has numerous applications in most industries. Depending on the type of data that is required to solve a particular problem, optical microscopy can provide information on particle size, particle morphology, color, appearance, birefringence, etc. There are many accessories and techniques for optical microscopy that may be employed for the characterization of the physical properties of materials and the identification of unknowns, etc. Utilization of a hot-stage accessory on the microscope for the characterization of materials, including pharmaceutical solids (drug substances, excipients, formulations, etc.), can be extremely valuable. As with any instrument, there are many experimental conditions and techniques for the hot-stage microscope that may be used to collect different types of data. Often, various microscope objectives, optical filters, ramp rates, immersion media, sample preparation techniques, microchemical tests, fusion methods, etc., can be utilized. 

During the preliminary research into any new material, whether it is a drug, polymer, metal, or combination of materials, only small amounts of samples are prepared. Often, many different tests must be performed on each of these small samples therefore, in order for a chemist to obtain chemical information about the sample, he must know or utilize chemical testing on a microscopic scale. 

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