Qualitative analysis infrared

They may be used as a fingerprint of a compound or element. This is useful in chemical identification (qualitative analysis). Infrared and NMR absorption spectra are widely used in the laboratory for this purpose. 

The use of vibrational Raman spectroscopy in qualitative analysis has increased greatly since the introduction of lasers, which have replaced mercury arcs as monochromatic sources. Although a laser Raman spectrometer is more expensive than a typical infrared spectrometer used for qualitative analysis, it does have the advantage that low- and high-wavenumber vibrations can be observed with equal ease whereas in the infrared a different, far-infrared, spectrometer may be required for observations below about 400 cm. ... 

Multidimensional gas chromatography has also been used in the qualitative analysis of contaminated environmental extracts by using spectral detection techniques Such as infrared (IR) spectroscopy and mass spectrometry (MS) (20). These techniques produce the most reliable identification only when they are dealing with pure substances this means that the chromatographic process should avoid overlapping of the peaks. 

K. A. Rrock and C. L. Wilkins, Qualitative analysis of contaminated environmental extracts by multidimensional gas cliromatography with infrared and mass specti al detection (MDGC-IR-MS) , pp. 167-178, copyright 1996, with permission from Elsevier Science. 

Mark, H., "Normalized distances for Qualitative Near-Infrared Reflectance Analysis", Anal. Chem. 1986 (58) 379-384. 

Many methods are currently available for the qualitative analysis of anthocyanins including hydrolysis procedures," evaluation of spectral characteristics, mass spectroscopy (MS), " nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy. - Frequently a multi-step procedure will be used for... 

The phase composition of glycine crystal forms during the drying step of a wet granulation process has been studied, and a model developed for the phase conversion reactions [88], X-ray powder diffraction was used for qualitative analysis, and near-infrared spectroscopy for quantitative analysis. It was shown that when glycine was wet granulated with microcrystalline cellulose, the more rapidly the granulation... 

ASTM Committee E13.ll, Practice for Near Infrared Qualitative Analysis , ASTM Committee E 13, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. 

Infrared spectra differ markedly from the typical ultraviolet or visible spectrum. Infrared spectra are marked by many relatively sharp peaks and the spectra for different compounds are quite different. This makes infrared spectroscopy ideal for qualitative analysis of organic compounds. 

When a solution is tested, both analyte and solvent absorption bands will be present in the spectrum, and identification, if that is the purpose of the experiment, is hindered. Some solvents have rather simple IR spectra and are thus considered more desirable as solvents for qualitative analysis. Examples are carbon tetrachloride (CC14, only C-Cl bonds), choloroform (CHC13), and methylene chloride (CH2C12). The infrared spectra of carbon tetrachloride and methylene chloride are shown in Figure 8.21. There is a problem with toxicity with these solvents, however. For quantitative analysis, such absorption band interference is less of a problem because one needs only to have a single absorption band of the analyte isolated from the other bands. This one band can be the source of the data for the standard curve since the peak absorption increases with increasing concentration (see Section 8.11 and Experiment 25). See Workplace Scene 8.2. 

Why is it that the infrared spectrum of an organic compound is more useful than the UV-VIS spectrum for qualitative analysis ... 

We discussed the fundamentals of mass spectrometry in Chapter 10 and infrared spectrometry in Chapter 8. The quadrupole mass spectrometer and the Fourier transform infrared spectrometer have been adapted to and used with GC equipment as detectors with great success. Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectrometry (GC-IR) are very powerful tools for qualitative analysis in GC because not only do they give retention time information, but, due to their inherent speed, they are also able to measure and record the mass spectrum or infrared (IR) spectrum of the individual sample components as they elute from the GC column. It is like taking a photograph of each component as it elutes. See Figure 12.14. Coupled with the computer banks of mass and IR spectra, a component s identity is an easy chore for such a detector. It seems the only real... 

Infrared spectroscopy is often used for qualitative analysis, and its powerful selectivity means that it can be used as a detector. However, the absorption of the eluent molecules, particularly in reversed-phase separations, often interferes with the detection of analytes. The infrared absorption detector therefore requires mechanical assistance to eliminate the solvent or needs powerful computer assistance to eliminate the background signal. 

ASTM E1790-04, Standard practice for near infrared qualitative analysis, in Annual Book of Standards, vol. 3.06, ASTM International, West Conshohocken, PA, 2008. 

The aim of qualitative analysis of homopolymers by infrared spectroscopy is the elucidation of polymer structure and compound identification. This often entails the identification of the functional groups and the modes of attachment to the polymer backbone [2,4,25,26], In the case of mixtures, the aim of qualitative... 

Roggo, Y., Edmond, A., Chalus, P., and Ulmschneider, M. (2005a), Infrared imaging for qualitative analysis of pharmaceutical solid forms and trouble shooting, Anal. Chim. Acta, 535, 79-87. 

Roggo, Y., Duponchel, L., and Huvenne, J.-P. (2003), Comparison of supervised pattern recognition methods with McNemar s statistical test Application to qualitative analysis of sugar beet by near-infrared spectroscopy, Anal. Chim. Acta, All, 187-200. 

An unknown substance, X, was isolated from rabbit muscle. Its structure was determined from the following observations and experiments. Qualitative analysis showed that X was composed entirely of C, H, and 0. A weighed sample of X was completely oxidized, and the H20 and C02 produced were measured this quantitative analysis revealed that X contained 40.00% C, 6.71% H, and 53.29% O by weight. The molecular mass of X, determined by mass spectrometry, was 90.00 u (atomic mass units see Box 1-1). Infrared spectroscopy showed that X contained one double bond. X dissolved readily in water to give an acidic solution the solution demonstrated optical activity when tested in a polarimeter. 

Liquids are usually analysed with cells which have dismountable IR windows. For qualitative analysis, a droplet of the sample is compressed between two NaCl or KBr disks without a divider. However, for quantitative analysis, either Infrasil quartz cells (with an optical path from 1 to 5 cm) or cells that have a variable or fixed width, generally smaller than 1 mm (see Fig. 10.17), can be used. In the mid-infrared, the latter consist of two KBr or NaCl windows with a spacer. The optical path length must be calibrated and periodically controlled. 

For qualitative analysis, two detectors that can identify compounds are the mass spectrometer (Section 22-4) and the Fourier transform infrared spectrometer (Section 20-5). A peak can be identified by comparing its spectrum with a library of spectra recorded in a computer. For mass spectral identification, sometimes two prominent peaks are selected in the electron ionization spectrum. The quantitation ion is used for quantitative analysis. The confinnation ion is used for qualitative identification. For example, the confirmation ion might be expected to be 65% as abundant as the quantitation ion. If the observed abundance is not close to 65%, then we suspect that the compound is misidentified. 

The analytical chemist can use Raman and infrared spectra in two ways. At tile purely empirical level, they provide fingerprints of the molecular structure and, as such, permit the qualitative analysis of individual compounds, either by direct comparison of the spectra of the known and unknown materials run consecutively, or by comparison of the spectrum of the unknown compound with catalogs of reference spectra. 

D.E. Chasan G. Norwitz, Qualitative Analysis of Primers, Tracers, Igniters, Incendiaries, Boosters and Delay Compositions on a Micro Scale by the Use of Infrared Spectroscopy , FA-T71-6-1 (1971), (AD 729 337)... 

ASTM E-1252. Standard Practice for General Techniques for Obtaining Infrared Spectra for Qualitative Analysis. 

A feasible solution for this complex challenge is to implement at least two analytical methods with which the course of the reaction can be followed a fast first method that allows qualitative control of the status of the catalyst performance and a second accurate, and in most cases more time consuming, analysis method that will allow a detailed evaluation of catalyst performance. The two analysis methods can be run on one analytical unit, e.g. a gas chromatograph with two different analysis protocols, or separate analytical units such as a gas chromatograph for accurate performance evaluation in combination with a non-dispersive infrared unit for fast qualitative analysis. 

Two infrared absorption methods (i.e., FTIR) and a Raman spectroscopic method were used to quantify polymorphic clopidogrel bisulfate Form-I and Form-II [16,17]. In addition, qualitative analysis of these polymorphs was also conducted using FTIR [16], where each sample was scanned over in the spectral region of 450-4000 cm-1 at a resolution of 4 cm-1. The sampling procedure used KBr pellets, loaded to contain approximately 3% of analyte. It was found that absorption bands associated with C-Fl and C-O bonds were stronger for Form-II relative to Form-I, and that unique absorption bands for Form-I and Form-II were observed at 841 and 1029 cm-1, respectively. These absorption bands were reported to be useful in the quantitative or qualitative analysis of clopidogrel polymorphs. 

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