Multiwavelength spectroscopic

Gampp, H., Maeder, M., Meyer, C. J., Zuberbtihler, A. D. Calculation of equilibrium constants from multiwavelength spectroscopic data. 1. Mathematical considerations. Talanta 1985, 32, 95-101. 

Tam, K. Y., Takacs-Novak, K. Multiwavelength spectroscopic determination of add dissodation constants a validation study. Anal. Chim. Acta 2001, 434,157-167. 

H. Gampp, M. Maeder, C.J. Meyer and A.D. Zuberbuhler, Calculation of equilibrium constants from multiwavelength spectroscopic data. Ill Model-free analysis of spectrophotometric and ESR titrations. Talanta, 32 (1985) 1133-1139. 

This is for univariate data what happens in the case of multivariate (multiwavelength) spectroscopic analysis. The same thing, only worse. To calculate the effects rigorously and quantitatively is an extremely difficult exercise for the multivariate case, because not only are the errors themselves are involved, but in addition the correlation stmcture of the data exacerbates the effects. Qualitatively we can note that, just as in the univariate case, the presence of error in the absorbance data will bias the coefficient(s) toward zero , to use the formal statistical description. In the multivariate case, however, each coefficient will be biased by different amounts, reflecting the different amounts of noise (or error, more generally) affecting the data at different wavelengths. As mentioned above, these... 

Emission spectra in the visual region were measured with a Simultaneous Multiwavelength Analyzer model CLA-SP2 (Tohoku Electronic, Japan). The wavelength range of the spectroscope was 400-850 nm. Light emission was determined for 180 s. 

Evolving Factor Analysis (EVA) This method is a further development of FA, where intrinsically ordered data can be investigated. Multiwavelength detection of the elution of compounds in a chromatogram in dependence on time is a typical example, and the spectroscopic investigation of simultaneous equilibria in dependence on the pH value can also be carried out by evolving factor analysis (EVA). 

Nonpulsatile optical spectroscopy has been used for more than half a century for noninvasive medical assessment, such as in the use of multiwavelength tissue analysis for oximetry and skin reflectance measurement for bilirubin assessment in jaundiced neonates. These early applications have found some limited use, but with modest impact. Recent investigations into new nonpulsatile spectroscopy methods for assessment of deep-tissue oxygenation (e.g., cerebral oxygen monitoring), for evaluation of respiratory status at the cellular level, and for the detection of other critical analytes, such as glucose, may yet prove more fruitful. The former applications have led to spectroscopic studies of cytochromes in tissues, and the latter has led to considerable work into new approaches in near-infrared analysis of intact tissues. 

Table 5-41. Other spectroscopic methods Multiwavelength analysis, NMR, raman spectroscopy, and surface photovoltage spectroscopy. ...

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