ULTRAVIOLET AND VISIBLE SPECTROPHOTOMETRY

There is a large amount of Hterature on the analysis of dyes and the most comprehensive treatment of the analytical chemistry of dyestuffs is found in Reference 271. Earlier papers dealing with the analytical chemistry of dyes in the environment mainly used paper, thin-layer, column, and high pressure hquid chromatography and ultraviolet and visible spectrophotometry (255,272—275). 

Fig. 17.8 Reproduced with permission from J. E. Steward (Ed.), Introduction to Ultraviolet and Visible Spectrophotometry, 2nd edn, Philips/Pye Unicam, Cambridge, 1985.

The scope of ultraviolet and visible spectrophotometry can be further extended when combined with a chromatographic separation step such as HPLC. The development of rapid-scanning detectors based on the linear photodiode array permits spectra to be acquired during the elution of peaks. Computer-aided manipulation of these spectra has led to new strategies for the examination of chromatographic peak homogeneity, based on classical techniques in spectroscopy. The use of microcomputers enables the development of archive retrieval methods for spectral characterisation (A. F. Fell etal, J. Chromat., 1984, 316, 423-440). 

The positions of peaks are sometimes described in terms of wavenumber, which has the advantage of being a linear function of energy but this term is much more frequently used in infra-red spectrophotometry. The practical unit most often used in ultraviolet and visible spectrophotometry is wavelength, usually expressed in nanometres (nm). The older units of wavelength, millimicron (m i,) and angstrom (A), are not recommended terms. The position of maximum absorbance of a peak is designated X. ... 

Spectroscopic Methods of Analysis Ultraviolet and Visible Spectrophotometry... 

Gorog, S. Ultraviolet and Visible Spectrophotometry in Pharmaceutical Analysis CRC Press, Inc. New York, 1995. 

Raghavan, R. Joseph, J.C. Ultraviolet and Visible Spectrophotometry in Pharmaceutical Analysis Swarbrick, J., Boylan, J., Eds. Marcel Dekker, Inc. New York, 1997 15, 293-339. 

Spectroscopic Methods of Analysis Ultraviolet and Visible Spectrophotometry / 3460 Starches and Starch Derivatives / 3476... 

ScHiLT AA and Jaselskis B (1964) Ultraviolet and visible spectrophotometry. In KoIthofflM, Elving PJ and Sandell EB, eds. Treatise on analytical chemistry, Part I (Theory and practice), Vol 5, section D-3, Optical methods of analysis (Meehan EJ, section advisor), pp. 2943-3056. John Wiley Sons, New York. 

In addition to ultraviolet and visible spectrophotometry, various other methods can be used to study the complexes cryoscopy, differential vapour pressure measurements, and infrared absorption spectrometry. , P25i- 256... 

Spectroscopic techniques used in essential oil analysis comprise ultraviolet and visible spectrophotometry, infrared spectrophotometry (IR), mass spectrometry (MS), and nuclear magnetic resonance spectroscopy (NMR), including the following H-NMR, C-NMR, and site-specific natural isotope fractionation NMR. Combined techniques (hyphenated techniques) employed in essential oil analysis are GC/MS, liquid chromatography/mass spectrometry, gas chromatography/Fourier transform infrared spectrophotometry (GC/FT-IR), GC/FT-IR/MS, GC/atomic emission detector, GC/isotope ratio mass spectrometry, multidimensional GC/MS. 

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