Infrared spectrophotometry applications

R.M. Issa, K.M. El-Marsafy and M.M. Gohar, Application of the near infrared spectrophotometry as an analytical procedure for the determination of water in organic compounds and pharmaceutical products, An. Quim., 84, 312-315 (1988). 

Excipients used in injectable formulations have to meet several stringent requirements. A positive identification test uniquely applicable to the excipients is required (e.g., infrared spectrophotometry and chromatography). It is important that manufacturers identify and set appropriate limits for impurities. These limits should be based upon appropriate toxicological data, or the limits described in national compendial requirements. Manufacturing processes should be adequately controlled so that the impurities do not exceed such established specifications. Solvents or catalysts used in the excipient production process should be removed to appropriate levels. If naturally derived, excipients should meet endotoxin levels and may require further testing for bovine spongiform encephalopathy (BSE) /... 

Mirabella, F. M., Jr. (1987) Applications of microscopic Fourier transform infrared spectrophotometry sampling techniques for the analysis of polymer systems. In The Design, Sample Handling and Applications of Infrared Microscopes (P. B. Rousch, ed.), American Society for Testing and Materials, Philadelphia, PA, pp. 74—83. 

Applications of Quantitative Infrared Spectroscopy Infrared spectrophotometry offers the potential for determining an unusually large number of substances because nearly all molecular species absorb in the infrared region. Moreover, the uniqueness of an infrared spectrum provides a degree of specificity that is matched or exceeded by relatively few other analytical methods. This specificity has particular application to the analysis of mixtures of closely related organic compounds. 

Atomic absorption allows the measurement of around 70 elements (see Figure 13.18). It is widely used because the method can accept samples of various forms at very low concentrations. The scope of applications is therefore considerable. As in visible or infrared spectrophotometry, it is necessary to carry out baseline corrections to eliminate fluctuations coming from the lamp and interfering absorptions. 

A positive identification test uniquely applicable to the excipients should be established. This should be achieved through analytical technology, such as infrared spectrophotometry and chromatography. 

The application of infrared spectrophotometry to the study of bacteria and fungi has been investigated by many workers. Stevenson and Bolduan (1952) proposed the use of this method for the identification of bacteria. They found that infrared spectra do not always group species as in the Bergey classification. For example. Pseudomonas (Family II) organisms and Escherichia (Family X) had similar spectra, whereas Micrococcus rosaceous and M. pyogenes var. aureus (Genus I, Family V) had very different spectra. 

Of the few electroanalytical monitors the ones used in the chloralkali industry are worth mentioning.Sulphate was determined in brines. Oflf-line conductometry was used to determine sulphate in the concentration range 25 - 500 mM with Ba " as titrant, or Pb " " as titrant when potentiometric measurement was used. These methods can, however, not compete with infrared spectrophotometry in this application. Water was determined in chlorine gas by coulometry with 100 % current efficiency. In this case the analyzer should be installed very close to the production plant. 

Miseo EV, GuUmette LW (1987) Industrial problem solving by microscopic Fourier transform infrared spectrophotometry. In Rousch PB (ed) The design, sample handling and applications of infrared microscopes. ASTM STP 949. American Society for Testing and Materials, Philadelphia, PA, USA, p 97 Wilhelm P (1996) Micron 27 341... 

With all the numerous applications listed above, infrared spectrophotometry suffers from two major disadvantages — the first one of them specifically for the biochemists. 

Establishment of the stereoconfiguration of the glycosidic bond is more complicated. Specific a- and jS-glycosidase enzymes have been used with considerable success, and application of infrared spectrophotometry seems to be useful (38). In the latter method the presence of a-linked D-glucose... 

A. Polesello, R. Giangiacomo. Application of near infrared spectrophotometry to the nondestructive analysis of foods a review of experimental results. Crit Rev Food Sci Nutr 18 203-237, 1983. 

Noel, T. R., Ring, S. G., Whittam, M. A., Glass transitions in low-moisture foods. Trends Food Sci. Technol. September 1990, pp. 62 Polesello, A., Gianciacomo, R., Application of near infrared spectrophotometry to the nondestructive analysis of food a review of experimental results. Crit. Rev. Food Sci. Nutr., 18, 203 (1982/83)... 

Rosenbaum wrote an earlier near-infrared review which is still useful. Groenewege has reviewed analytical applications of this region. Beckman Applications Data Sheet DK-72-M1 concerns near-infrared spectrophotometry. 

The references given in this bibliography are, principally, to the theoretical considerations, principles, methodology, and instrumentation of infrared spectrophotometry and Raman spectra. References to specific applications are included wherein new techniques are given or the application may be of general interest. Numerous references to bibliographies giving specific applications are to be found in this compilation. 

R. S. Browning, S. E. Wiberley, and F. C. Nachod, Application of Infrared Spectrophotometry to Quantitative Analysis in the Solid Phase, Anal. Chem. 27, 7, 1955. 

While infrared spectrophotometry is most useful for the qualitative analysis of surfactants, various quantitative methods have been developed for well-characterized systems. For example, an attenuated total reflectance cell with a ZnSe crystal is useful for direct analysis of aqueous anionic surfactant solutions by FTIR, while avoiding the deleterious effects of water on the usual transmission cells. In this case, the sulfonate absorbance at 1175 cm" , or the sulfate absorbance at 1206-1215 cm , is used for quantification (10,26). In another application, the weak absorption bands in the 1429-1333 cm" region are used to measure the relative amounts of linear and branched chain alkylbenzene sulfonates extracted from environmental waters (27). This is the one advantage of the infrared technique over those that have supplanted it for wastewater analysis its ability to differentiate the straight and branched chain compounds (28). No procedure will be given here, since the cleanup prior to IR analysis can be handled adequately by the method for LAS analysis by desulfona-tion/gas chromatography, described in Chapter 8. 

Test 2 Examine by infrared absorption spectrophotometry, according to the general procedure (2.2.24), comparing with spectrum obtained with primaquine diphosphate Chemical Reference Substance (CRS). Examine the substance as discs prepared as follows dissolve separately 0.1 g of primaquine diphosphate and the reference substance in 5 mL of water R, add 2 mL of dilute ammonia R and 5 mL of chloroform R and shake dry the chloroform layer over 0.5 g of anhydrous sodium sulfate R prepare a blank disc using about 0.3 g of potassium bromide R, apply dropwise to the disc 0.1 mL of the chloroform layer, allowing the chloroform to evaporate between applications dry the disc at 50 °C for 2 min. 

Hughes, E. 1966. Applications of absorption spectrophotometry (infrared and visible) to the determination of impurities in tributyl phosphate and degraded tributyl phosphate/ kerosene mixtures. PG Report 737. 

The selective absorption of ultraviolet, visible and infrared radiation by molecules is explained in a descriptive manner that stresses how the noncontinuous energy requirements of chemical substances can only be satisfied by photons that have energy values equivalent to that of the differences in energy levels of the molecule in question. The meaning and quantitative significance of Beer s Law is briefly discussed. The components of a simple spectrophotometer are illustrated, accompanied by a demonstration of the operation of a spectrophotometer in the laboratory. Actual applications of the techniques of spectrophotometry are described during the presentation of relevent topics, for example, in drug identification. 

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