Differential spectroscopy

To overcome the limitation of detecting only a color change in the sensing colloidal crystal films, we apply a differential spectroscopy measurement approach coupled with the multivariate analysis of differential reflectance spectra. In differential spectroscopy, the differential spectrum accentuates the subtle differences between two spectra. Thus, in optical sensing, when the spectral shifts are relatively small, it is well accepted to perform measurements of the differential spectral response of sensing films before and after analyte exposure6 19. Therefore, the common features in two spectra of a sensing film before and after analyte exposure cancel and the differential spectrum accentuates the subtle differences due to analyte response. 

Sanghavi and Kulkami estimated the drug in the presence of its degraded products by differential spectroscopy [22]. Sastry et al. determined diloxanide furoate by a spectrophotometric method [23]. 

Chiral metal alkoxides M(OR)4 have been developed as asymmetric variants of ordinary Lewis acids, such as A1C13 and ZrCU, and are used as catalysts for selective carbon-carbon bond formation. Thus, starting from bidentate l,l -bi-2-naphthol derivatives (BINOL) and SnCU, a series of chiral tin(iv) aryloxides 221 (Figure 7) was prepared and successfully applied to the enantioselective Diels-Alder reaction <2006TL873>. Similar silocanes obtained from menthone- or camphor-derived 2,2 -biphenols have been obtained and their configuration was analyzed by NOE differential spectroscopy (NOEDS) <1997JOC7156>. 

Effect of thermostabilizers on the polymer properties was studied by different physicochemical methods. For example, in the work [260] method of DSS (differential spectroscopy) was used to define the effect of polyester-imide on thermo-physical properties of PETP. By this method it was found out that polyester-imide reduces PETP ability to crystallization. Methods of thermogravimetric analysis (TGA) and infrared spectroscopy in the nitrogen atmosphere were used in the work [261] to define thermal stability of the mixture of PETP and polyamide with the additive - modifier - polyethylene. It has been found that introduction of the additive decreases activation energy which positively tells on the ability of PETP to thermal destruction. 

McCabe and Fisher (1965) have measured the excluded volume of protein molecules by means of differential spectroscopy in the near-infrared region. The excluded specific volumes of bovine serum albumin and lysozyme were found to be 0.74 ml/g and 0.68 ml/g, respectively, values which are close to the values of apparent specific volume reported in the literature (Dayhoff et al., 1952 Sophianopoulos et al, 1962). The authors suggested that excluded specific volume as measured by their method is closely associated with the partial specific volume of the protein molecule. 

Song W, Yang J (2012) Optofluidic differential spectroscopy for absorbance detection of sub-nanolitre liquid samples. Lab Chip 12 1251-1264... 

Fendler, J.H., Patterson, L.K. Solubilization of benzene in aqueous cetyltrimeth-ylammonium bromide measured by differential spectroscopy. Comment. J. Phys. Chem. 1971, 75(25), 3907 J. Phys. Chem. 1970, 74(26), 4608- 609. 

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