Ultraviolet second derivative spectra

Second derivative spectroscopy is a means to extract information from the spectrum. In contrast to the relatively featureless UV spectra, the second derivatives of UV spectra are characterized by 2 sharp peaks and troughs [6,7]. Figure 1 shows the ultraviolet spectra of yeast enolase at 0.28 and 200 MPa and Figure 2 shows the second derivative of those spectra. 

Second derivative ultraviolet spectroscopy is a simple yet powerful technique for highlighting the fine structure of spectral curves. It involves calculating the second derivative of a spectrum with respect to wavelength and plotting the derivative rather than the spectrum itself. Second derivative absorbance spectra of lignin model compounds, milled wood lignins and lignosulfonates have been published (Lin 1982). 

Hgure 7 Influence of the modulation amplitude a [8] on the shape of a second-order derivative spectrum [19]. The example was determined by means of an aqueous sample containing approx. Imgl of each benzene, toluene, p-xylene. (Reprinted with permission from Vogt F, Tacke M, Jakusch M, and Mizaikoff B (2000) An ultraviolet spectroscopic method for monitoring aromatic hydrocarbons dissolved in water. Analytica Chimica Acta 422 187-198 Elsevier cf. Erratum (2001) Analytica Chimica Acta 431 167.)... 

Hydroxy-8-azapurine was shown by rapid-reaction techniques (see Section II, E) to be anhydrous in the anion and hydrated in the neutral species. The hydration reaction has a half-time of about 0.5 second, which is too rapid for exact measurements with existing apparatus. The cation of 2-amino-8-azapurine was shown to have an anomalous value and ultraviolet spectrum, although its 6-methyl derivative is quite normal. Hydration in this case proved to be too fast to register in the rapid-reaction apparatus. 

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