KBr pellets

In addition, compression methods that utilize hydraulics and levers may be used. These sometimes have pressure gauges that allow the analyst to apply a certain optimal force in order to maximize the chances of making a quality pellet. To make a quality pellet, in addition to using the optimum pressure, it is important for the KBr and the sample to be dry, finely powdered, and well mixed. An agate mortar and pestle is recommended for the grinding and mixing of the KBr and sample prior to compression. See Workplace Scene 8.3. 

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Pellets of such oxides are usually prepared by mixing 5—10 wt % of the oxide with KBr and pressing a pellet that is several mm thick. Although the preparation of such systems is not difficult, often the pellet must be pressed for long periods of time to allow the KBr to fuse around the oxide particulates. Once prepared, in spectra of these pellets can be acquired in standard KBr pellet holders. 

Measurements. Infra-red spectra for the region 600-4000 cm-1 were measured with a Perkin-Elmer Model 710B spectrometer on samples pressed in KBr pellets. Magnetic susceptibilities were measured with a vibrating sample magnetometer (Princeton Applied Physics) as previously described.(4)... 

Plutonium(IV) polymer has been examined by infrared spectroscopy (26). One of the prominent features in the infrared spectrum of the polymer is an intense band in the OH stretching region at 3400 cm 1. Upon deuteration, this band shifts to 2400 cm 1. However, it could not be positively assigned to OH vibrations in the polymer due to absorption of water by the KBr pellet. In view of the broad band observed in this same region for I, it now seems likely that the bands observed previously for Pu(IV) polymer are actually due to OH in the polymer. Indeed, we have observed a similar shift in the sharp absorption of U(0H)2S0ir upon deuteration (28). This absorption shifts from 3500 cm 1 to 2600 cm 1. 

Figure 4. Infrared spectra of KBr pellets containing Pu(IV) polymer precipitates, (A) prepared in -purged glove hag free of CO2 (B) prepared in laboratory atmosphere. (Reprinted with permission from Ref. 6.)...

I> = (dc/df)//abs where dc/dr is the rate of disappearance of the olefinic double bonds per unit volume and /abs the rate at which the incident light is absorbed per unit volume of the KBr pellet containing the sample. The rates of disappearance of the olefinic double bonds during oligomerization and polymerization were monitored by infrared (IR) spectroscopy. 

Applications Identification of polymer additives by TLC-IR is labour intensive and comprises extraction, concentration of extracts, component separation by TLC on silica, drying, removal of spots, preparation of KBr pellets and IR analysis. The method was illustrated with natural rubber formulations, where N-cyclohexyl-2-benzothiazyl sulfenamide, IPPD and 6PPD antioxidants, and a naphthenic plasticiser were readily quantified [765]. An overview of polymer/additive type compounds analysed by transfer TLC-FTIR is given in Table 7.80. 

Low molecular weight solids were dispersed in KBr pellets polymer films were cast from CHCI3. Intrinsic viscosities were measured by standard procedures using a Cannon Ubbelohde dilution viscometer. 

Infrared spectra of KBr pellets were measured on a Nicolet 10DX FTIR. Elemental analyses were performed using Parr peroxide bombs and by MHW Laboratories (Phoenix, AZ). 

Infrared Red Studies. Infrared spectra were recorded in a Perkin Elmer PE-M330 infrared spectrometer. IR studies of the metal films using either KBr pellets or Fluorolube yielded bands at 2960(s), 2580(m), 1750(s), I635(m), and 570(w) cm-1. 

The infrared absorption spectrum of miconazole nitrate was obtained in a KBr pellet using a Perkin-Elmer infrared spectrophotometer. The IR spectrum is shown in Fig. 4, where the principal peaks were observed at 3140, 3070, 2995, 2920, 1566, 1525, 1445, 1385, 1310, 1070, and 710 cm-1. Assignments for the major infrared absorption band are provided in Table 2. Clarke reported principal peaks at 1085, 1319, 827, 1302, 1038, and 812 cm-1 (miconazole nitrate, KBr disc) [2]. 

Fig. 4. Infrared absorption spectrum of miconazole nitrate (KBr pellet).

Fig. 4. (A) The infrared absorption spectrum of sodium valproate obtained in a KBr pellet. (B) The infrared absorption spectrum of valproic acid obtained in a KBr pellet.

Figure 2. Infrared Spectrum of Aspirin (U.S.P. Reference Standard) KBr pellet. Instrument Perkin-Elmer Model 621...

The infrared spectrum of bromocriptine mesilate in a KBr pellet is given in fig. 1. It was recorded on a Perkin Elmer 257 infrared spectrophotometer. 

Figure 1. Infrared Spectrum of Bromocriptine Mesilate in a KBr Pellet. 

Bromocriptine can also be identified as the base by ir spectroscopy after extraction from the dosage form with ethanol and removal of the solvent, both in solution and in a KBr pellet (33). ... 

The infrared spectrum of calcitriol is shown in Figure 1 (1). The spectrum was recorded on a Perkin-Elmer Model 283 Grating Infrared Spectrophotometer and was measured in a KBr pellet which contained 1 mg of calcitriol in 300 mg of KBr. 

The infrared spectrum of nalidixic acid in a KBr pellet is presented in Figure 3. The spectrum was obtained on a Perkin-Elmer Infrared Spectrophotometer Model 21. It agrees with the spectrum presented by Salim and Shupe.(2)... 

Remove both bolts. A KBr pellet, containing your sample, should be in the press. Transparent is excellent. Translucent will work. If the sample is opaque, you can run the IR, but I don t have much hope of your finding anything. 

Sample beam aperture. This is where you put the holder containing your sample, be it mull or KBr pellet. You slip the holder into the aperture window for analysis. 

In any case, if the peaks are too large, with the baseline in the proper place, your sample is just too concentrated. You can wipe some of your liquid sample or mull off one of the salt plates or remake the KBr pellet using less compound or more KBr. Sorry. 

Thickness. Unless you re using solution cells, thin film for neat liquids. Leave this blank for KBr samples (unless you ve measured the thickness of the KBr pellet, which you shouldn t have done). 

Figure 11.1. FTIR (KBr pellet) spectra of (A) triacrylate 3 and (B) its curing with AIBN at 100°C for...

Diepoxy 6 (0.84g, 1 mmol) and diimidediol 3 (1.07 g, 1 mmol) were mixed well and the mixture heated at 110°C overnight, during which time no change took place. Tetramethylammonium bromide in a catalytic amount was added, mixed well, and heated at 110°C. After one day a brittle transparent solid was obtained. During two more days it became a very hard solid 7. IR (KBr pellet) 3480 (OH), 1785 and 1730 (imide), 1452, 1388, 1300-1100 (F), 1050, 1018, 983, 750, 730, 716, 708 cm1. 

Figure 14.3. Sample holders for various spectrophotometric measurements. (A) UV-Vis cells (B) infrared ATR plate and stand-plate behind which B is attached when in use (C) simple KBr pellet maker using the two bolts and the center dye (D) a sample tube for NMR spectroscopy. 

Figure 14.6. Infrared spectra of a KBr pellet of 3% sodium humate (Aldrich) and an NMR spectrum of a mixture of toluene, hexanoic acid, and octanal. The functionalities responsible for the absorption features are labeled. 

The present procedure2 describes the conversion of resin-bound, primary aliphatic amines into isothiocyanates and the conversion of the latter into 3-aminothiophenes. The generation of isothiocyanates is related to known procedures,3 in which amines are first treated with carbon disulfide and the resulting dithiocarba-mates are desulfurized by treatment with a condensing agent (alkyl chloroformates, carbodiimides, lead or mercury salts, etc.). The presence of resin-bound isothiocyanates on the polystyrene support could be qualitatively ascertained by infrared spectroscopy (KBr-pellet strong absorption at 2091 cm-1). 

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