Potassium bromide pellet

Figure 6 shows the infrared spectrum of halcinonide run as a potassium bromide pellet, using a Perkin-Elmer Model 621 infrared spectrometer. Below are the interpretations of various absorbances.19... 

Infrared Spectrum of Halcinonide, Potassium Bromide Pellet. See text for details. 

Figure 2. Infrared Absorption Spectrum of Hydralazine Base, Potassium Bromide Pellet and Mull.

The infrared spectrum, for a sample prepared as a potassium bromide pellet, is highly characteristic of the compound. The spectrum is shown in Figure 6 and Table 3 lists the band assigiunents. 

Calcium was determined by an EDTA method carbon and hydrogen by the combustion method total nitrogen by the Kjeldahl method sulfur by the Eschka method infrared spectra by the potassium bromide pellet technique. 

All infrared absorption spectra were taken with a Beckman IR-4 spectrophotometer on potassium bromide pellets. 

The infrared spectra of the coal and the various extracts were recorded on a Baird, Model GY-1 (Ireland Mine vitrain concentrate) and on a Perkin Elmer Model 337 spectrophotometer (Bruceton coal). The samples were prepared by the potassium bromide pellet technique. The high resolution proton NMR spectrum of the benzene soluble extract from Ireland Mine vitrain concentrate was recorded on a Varian A-60 spectrometer in 10% deuterated chloroform (CDCh) solution, using tetrametnylsilane internal standard. 

The infrared spectrum of moxalactam disodium in a potassium bromide pellet is presented in Figure 1. The assignments for the spectral peaks are given in Table 1. 

The infrared spectrum of a sample in a potassium bromide pellet may be used as an identity test. In such cases, the infrared spectrum of the sample should compare favorably with the moxalactam disodium reference spectrum over the range of 2.5 to 16 microns. 

C/min and secondly a ramp from 100 - 300°C at 20°C/min was used. Injector and detector temperatures were maintained at 270°C and 300°C respectively. GLC-FID/FPD analysis was performed on a Varian 3400 gas chromatograph using the same chromatographic conditions as used in the GC-MS runs. FTIR spectroscopy was performed on a Nicolet instrument using the thin film on sodium chloride plates technique for liquids and the potassium bromide pellet technique for solids. 

A group in Latvia and Russia [78] analysed microbial cell mass by a fairly simple classical infrared spectroscopic method, recording spectra of dried biomass embedded in potassium bromide pellets with a dispersive IR spectrometer. They could calibrate the evaluation for four major groups of cellular... 

Table 5 Correlation of the Fundamental Frequencies (cm ) of l,3-Dichalcogenole-2-thiones and 1,3-Dichal-cogenole-2-selenones in Potassium Bromide Pellets (81jst<71)1)...

Fourier transform infrared spectroscopy (FTIR) was also used to monitor the degree of pyrolysis for various samples at different temperatures. The KBr (potassium bromide) pellet of sample was prepared for FTIR analysis. 

The potassium bromide-pellet method provides the most convenient way to detect a slight polymerizability at room temperature using the following operation a few milligrams of the monomer are embedded in a KBr pellet, and the change upon irradiation is followed by IR spectroscopy. All the polymers thus obtained, their properties and the polymerization conditions are listed in Table 1. 

The IR spectra of phenazine and its derivatives have been studied in carbon disulfide solutions and as potassium bromide pellets. Because of the high symmetry of the phenazine ring, many of the fundamental vibrations are not visible in IR, but in Raman spectra. The complexity of Raman spectrum varies with the physical form of the sample. Characteristic IR absorption bands of phenazine occur at 3065, 1515, 1437, 1362, 1112, 1029, 958, 905, 820, 752, 745 cm. ... 

IR spectra were obtained from potassium bromide pellets on a Beckman IR-12 spectrophotometer. 

Figure 2. Equipment useful in preparing micro potassium bromide pellets...

Figure 7. Infrared spectra of Abate mosquito larvicide by multiple in-ternal reflectance and micro potassium bromide pellet...

Figure 7 shows the spectra obtained from 4.9 /xg of Abate mosquito larvicide, using both the micromultiple internal reflectance and micro potassium bromide pellet techniques. The technique of Curry et al (18), dispensing the solution of the insecticide onto the potassium bromide... 

Ormosanine generates dextrorotatory piptanthine whereas piptanthine from O. nanus is levorotatory. The IR-spectra confirm the configuration of ormosanine and piptanthine at C-6. The former displays a trans band (boat configuration of ring B) only in potassium bromide pellets whereas the latter shows the trans band in solution as well as in potassium bromide. 

Spectra of gases are taken using enclosed cells, with an evacuated cell as a reference. Spectra of solids may be taken in the form of pellets. Potassium bromide pellets similar to those used in infra red spectroscopy have been found suitable. Pellet holders for measurements on solids are commercially available. In order to avoid complications due to nonparslM sides of solid samples, a rough-ground quartz diffuser is placed In front of the photo-cell. 

The solvent elimination approach is better than the one above as full spectral information from the analytes can be obtained and the chromatographic conditions do not have to be modified as much. In practice, the elnting compounds are deposited onto potassium bromide pellets, the mobile phase is evaporated and the pellets are then transferred to the FTIR for spectral analysis by diffuse reflectance. Hence the solvents nsed in the mobile phase must be more volatile than the analytes being smdied. A microdispenser for interfacing LC to IR or Raman which uses the solvent elimination approach has been reported . 

Spectroscopic Techniques. UV-visible spectra were obtained with a double -beam UV-visible spectrophotometer (Beckmann). The asphaltenes were examined as solutions in chloroform (0.005-0.1 g per mL) with chloroform in the compensating beam. IR spectra were recorded either as potassium bromide pellets (0.1 g of asphaltene per gram of potassium bromide) or as solutions in chloroform (0.1 g/mL). 

In view of possible differences between the materials used for the present lETS studies and those used by other workers in their IR and Raman studies, IR spectra were obtained for the same samples of 4-hydroxybenzoic acid and 4-aminobenzoic acid used in the lETS experiments so that direct comparisons could be made. Samples in the form of potassium bromide pellets were examined over the range 500-4000 cm" the results are given in Table IV together with the corresponding lETS results. 

The carbonyl stretching absorption, which occurs at about 1730 to 1700 cm for the dimer, is usually broader and more intense than that present in an aldehyde or a ketone. For most acids, when the acid is diluted with a solvent, the C=0 absorption appears between 1760 and 1730 cm for the monomer. However, the monomer is not often seen experimentally, since it is usually easier to run the spectram as a neat hquid. Under these conditions, as well as in a potassium bromide pellet or a Nujol mull, the dimer exists. It should be noted that some acids exist as dimers even at high dilution. Conjugation with a C=C or aryl group usually shifts the absorption band to a lower frequency, as predicted in Section 2.14A (p. 52) and as shown in the spectrum of benzoic acid (Fig. 2.46). Halogenation on the a carbon leads to an increase in the C=0 frequency. Section 2.18 discusses salts of carboxylic acids. 

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