Spectral correlation

McLafferty, F. W., and Venkataraghaven, R. Mass Spectral Correlations, 2nd ed. (Advances in Chemistry Series). 1982. 

F.W. McLafferty, Mass Spectral Correlations Advances in Chemistry Series No 40, AmChemSoc, Washington, DC (1963) 12) Anon, Index of... 

McCombie G, Staab D, Stoeckli M, et al. Spatial and spectral correlations in MALDI mass spectrometry images by clustering and multivariate analysis. Anal. Chem. 2005 77 6118-6124. 

Figure 1. Fiber optic system comprising a light source (1), optical filters (2, 3) for measurement of the concentration of a reagent solution. The fiber bundle (4), after passing the solution (16), is divided into three bundles (6-8) and light intensity is measured at three wavelengths in order to enable spectral correlation at different wavelengths.

Table 9.8 Simplified infrared spectral correlation charts... 

Mass spectral studies, including low voltage techniques and accurate mass measurements, have been reported by Hoffman (40) on tetracycline and eight related compounds. As a result of good spectral correlations among these compounds, the major fragmentation processes are discussed in terms of two compounds in the series 5a,6-anhydrotetracycline and... 

F.W. McLafferty and R. Venkataraghavan, Mass Spectral Correlations, 2nd Ed, American Chemical Society Advances in Chemistry Series 40, Washington, DC, 1982, pp. 124. 

The multivariate tools typically used for the NIR-CI analysis of pharmaceutical products fall into two main categories pattern recognition techniques and factor-based chemometric analysis methods. Pattern recognition algorithms such as spectral correlation or Euclidian distance calculations basically determine the similarity of a sample spectrum to a reference spectrum. These tools are especially useful for images where the individual pixels yield relatively unmixed spectra. These techniques can be used to quickly define spatial distributions of known materials based on external reference spectra. Alternatively, they can be used with internal references, to locate and classify regions with similar spectral response. 

Aminopyrimidines have been studied by Albert et al. (1948), and, by relying on the pAj-values at 20° of aminopyridines, there is no doubt that the 4-amino-derivative is protonated on the ring nitrogen N-1 (pAj = 5 69, as compared with pA = 1-23 for unsubstituted pyrimidine). The 2-amino-derivative is a weaker base (pAg = 3 45) and the 5-amino-derivative is weaker still (p/Cg = 2-60). An interesting ultraviolet spectral correlation has recently been pointed out (Albert and Taguchi, 1973) between compounds containing the 2-aminopyrimidinium and 2-pyrimidone structures ([59] and [60]). 

O-acetate (162), which possesses a bridgehead double bond, was established by X-ray analysis. The structures of the congeners were then related to this by a series of spectral correlations. Cinnzeylanine (163) and its desacetoxy alcohol, cinnzeylanol, are insecticidal polyhydroxylated pentacyclic diterpenoids, which were isolated from Cinnamonum zeylanicum. Their structure, which is similar to that of ryanodine, was established by X-ray analysis. 

Most pharmaceutical production is performed in batches, both when synthesizing active compounds and manufacturing pharmaceutical formulations. NIR can measure the final state in batch production in terms of spectral similarity, using SIMCA, spectral correlation, or spectral distance. Individual batch development can also be monitored using PCA. Several parameters of the same product can be... 

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