Transparent pellet

Transparent solid samples can be analyzed directly by placing them in the IR beam. Most solid samples, however, are opaque and must be dispersed in a more transparent medium before recording a traditional transmission spectrum. If a suitable solvent is available, then the solid can be analyzed by preparing a solution and analyzing as described earlier. When a suitable solvent is not available, solid samples may be analyzed by preparing a mull of the finely powdered sample with a suitable oil. Alternatively, the powdered sample can be mixed with KBr and pressed into an optically transparent pellet. 

Solid samples or solid extracts can be mixed and ground with potassium bromide (KBr),pressed to form a transparent pellet, and a spectrum obtained from the pellet (see C in Figure 14.3). There are gas cells for obtaining spectra of gases and many other methods for obtaining spectra from liquid and solid samples that are not as frequently used as these [13-17],... 

The identity of pergolide mesylate is determined using the specificity of infrared spectroscopy, which differentiates it from any synthetic intermediates, process related substances or degradation products. Pergolide mesylate is triturated with potassium bromide and pressed into a transparent pellet for spectroscopic analysis. The identity is confirmed by comparison to a reference standard spectrum obtained under similar conditions. 

GPa (6 tons cm ). Without evacuation (e. g. when moist air is present during pressing) it is impossible to obtain highly transparent pellets. The size of the ground particles should not exceed 2 pm, otherwise scattering losses may result IR spectra obtained by the pellet technique often exhibit bands at 3450 and 1640 cm due to adsorbed moisture. Without the addition of an internal standard the pellet technique is not suitable for quantitative measurements because the thickness is not precisely reproducible and the size of the IR bands depends on the dispersion of the sample (see Fig. 6.3). 

The materials used were Polysulfone (PSf, Sigma-Aldrich, Spain, transparent pellets of Mw = 16,000) as polymer, dimethylformamide (DMF, Scharlab, reagent grade ACS-ISO) as solvent, vanillin (Acros organics, 99% pure) as core material and distilled water as nonsolvent. 

Features Offers fiexibiiity, iow temp, processing, good chem. resist. Properties Transparent pellets sp.gr. 1.96 melt flow 5-15 (265 C/5 g) m.p. 150-160 C tens. str. 20 N/mm elong. 450% flamm. VO Dyneon THV 415 [Dyneon]... 

Properties Nearly transparent pellets melt index 6.0 dg/min dens. 0.955 g/cm soften, pt. (Vicat) 49 C tens. str. 15 MPa tens, elong. 750% Shore hardness D 34 28% VA... 

The sample is finely ground with pure dry KBr, placed in a die, a vacuum applied (130-260 Nm of Hg) to remove entrained air and finally pressed in a hydraulic press to form a transparent pellet or disc. The pellet is placed in a pellet holder, positioned in the spectrometer and the spectrum recorded. 

The Fourier transform infrared (FT-IR) spectroscopy (Perkin-Elmer, GX Model) was used to examine the changes in functional gronps that may have been caused by the treatments. The samples were ground and mixed with KBr. The resultant powder was pressed into transparent pellets and analyzed in transmittance mode within the range of 4000600 cm. ... 

A Fourier transform infrared spectroscopy (FTIR) study was obtained by using Perkin-Elmer spectrometer 100, USA. Prior to this analysis, kenaf whiskers were mixed with KBr to prepare homogeneous suspensions and afterwards pressed into transparent pellets and analyzed in transmittance mode within the range of 4000-500 cm. In the case of thin nanocomposite film (Cellulose Acetate Butyrate [CAB] and kenaf whiskers) the analysis was done within the range of 4000-500 cm transmittance mode. 

Transfer supernatant to a new tube, leaving the transparent pellet behind, Add 2,5 vol. of cold ethanol. Mix by inversion and leave for 5-30 min at -70 C Spin as above for 10 min. Wash the pellet with 1 ml of cold 70% (v/v) ethanol. Air dry the DNA pellet and resuspend it into 10-20 fjil water or TE buffer. 

Theoretically, the pellet should be transparent and look like a piece of glass. In practice pellets vary from completely transparent to completely opaque. There are many instances where transparent pellets yield miserable spectrograms while spectrograms from opaque pellets are excellent If the pellet appears to be completely fused, it should be usable. 

Solid Analysis Finely divided and dispersed solids in alkali halides (KBr is the most widely used). The mixture in the proportion of 1 mg of sample 300 mg of KBr is pressed, forming a clear and transparent pellet. Material that may form films, such as polymers and resins, is directly analyzed and the film must be as thin as possible. For surface characterization the sample is prepared in a the form of a self-supported pellet, where a small quantity of solid ( 20 mg) is pressed in order to obtain a thickness of decimals of millimeters. 

KBr Pellet A transmission sampling technique most commonly used on powders and solids. The technique involves grinding the sample and KBr, diluting the sample in the KBr, then pressing the mixture to produce a transparent pellet. The pellet is then placed directly in the infrared beam. 

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