Microscopic samples

Fluorescence Microscope. A useful light microscope utilizes UV light to induce fluorescence in microscopic samples (40). Because fluorescence is often the result of trace components in a given sample rather than intrinsic fluorescence of the principal component, it is useful in the crime laboratory for the comparison of particles and fibers from suspect and crime scene. Particles of the same substance from different sources almost certainly show a different group of trace elements. It is also very useful in biology where fluorescent compounds can be absorbed on (and therefore locate and identify) components of a tissue section. 

The first linkage between a microscope and an IR spectrophotometer was reported in 1949 [15]. Today, every manufacturer of IR spectrophotometers offers an optical/IR microscope sampling accessory. The use of optical and IR microscopy is a natural course of action for any solid state investigation. Optical microscopy provides significant information about a sample, such as its crystalline or amorphous nature, particle morphology, and size. Interfacing the microscope to an IR spectrophotometer ultimately provides unequivocal identification of one particular crystallite. Hence, we have the tremendous benefit of IR microscopy for the identification of particulate contamination in bulk or formulated drug products. 

Pocklington and Hardstaff [432] react sediment samples with 1,3,5-tri-hydroxybenzene in alcoholic hydrochloric acid to produce a colour in the particulate lignins, facilitating their identification under the microscope. Samples high in lignins can then be subjected to the normal methods of analysis. This is an excellent screening technique (semi-quantitative). 

Because of the small amounts of solid reactant in the microscope sample, analyses of reaction products are performed with larger samples in a microreactor operating under similar conditions, and these are used for microstructural correlations. 

Autofluorescence or primary fluorescence Fluorescence from objects in a microscope sample other than from fluorophores. In mammalian tissues,... 

Transmission Electron Microscopy Transmission electron microscopy data were obtained by personnel in the Ultrastructure Laboratory at the Virginia-Maryland College of Veterinary Medicine using a JEOL lOOCX-II transmission electron microscope. Samples were imbedded in Poly-bed 812 epoxy resin and cured at 50-60°C for 2-3 days. Samples were then sectioned to between 800 and 1000 on either a Sorval MT2B or an LKB IV Ultramicrotome using glass knives and were placed on 200 mesh copper grids. 

As described in the previous section, the femtosecond fluorescence up-conversion microscope enabled us to visualize microscopic samples based on position-depen-dent ultrafast fluorescence dynamics. However, in the imaging measurements using the fluorescence up-conversion microscope, XY scanning was necessary as when using FLIM systems. To achieve non-scanning measurements of time-resolved fluorescence images, we developed another time-resolved fluorescence microscope. 

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. 

C. Yi and M. Gratzl, Diffusional Mictrotitration Reagent Delivery by a Diffusional Microburet into Microscopic Samples, Anal. Chem. 1994, 66, 1976 ... 

The terms element and atom are often used in a similar context. You might hear, for example, that gold is an element made of gold atoms. Generally, element is used in reference to an entire macroscopic or microscopic sample, and atom is used when speaking of the submicroscopic particles in the sample. The... 

Microspectroscopy applies the identification power of infrared spectroscopy to the microscopic realm. Contaminants on printed circuit boards, blemishes in coatings, and other production defects can be isolated in situ and analyzed (see Electronics, coatings). Analysis of flaws that develop during use illuminates the method of failure. Microscopic samples, such as particulates filtered from air, can be analyzed individually. The forensic applications are many paint chips, single fibers, explosive residues, and inks on currency can all be identified nondestmctively (see Forensic chemistry). The structures of layered materials, such as laminated polymer films, are studied via microspectroscopy by cross-sectioning the materials and examining the individual layers edge on (47). 

But also a treatment with 100% TFA at high temperature results in a poor hydrolysis of cellulose. After a reaction time of 4 hr at 120°C in a closed tube, about 80% of the charge was precipitated when diluting the TFA. This residue could not be completely hydrolyzed with diluted TFA, though the average degree of polymerization was only about 30. In the electron microscope, samples of cellulose precipitated from TFA solution and treated with diluted TFA show broad crystallike platelets (Figure 5). 

Generally, this technique is used to analyze samples that are available either in small quantity or a small entity. Gels within a rubber sample, have to be microtomed (i.e., cut into very thin slices) and mounted in KBr plates in a Microscopy Lab. Samples contaminated with inorganic components are usually analyzed by both X-ray and FTIR Microscope. Sample size 20 microns can be analyzed by the FTIR-microscope. 

There is no inherent sample size restriction, large or small, but is fixed by the optical components used in the instrument. The diffraction limit of light, roughly a few cubic micrometers depending on the numerical aperture of the optics used and the laser s wavelength, sets the lower bound.7 In a process application, the type of fiber optics used also affects sample volume examined. Macroscopic to microscopic samples can be measured with the appropriate selections of laser wavelength, laser power, and optics. 

Water (moisture) content determination Quick sample heating Microscopic sample preparation Sample incineration and melting... 

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