Columns optical absorbance

Expansion of Module 3 to include rules for selection of detectors and detector parameters. The rules will handle optical absorbance and fluorescence (including pre- and post-column deri-vatization) and electrochemical detection. 

Figure 5. Optical absorbance at 280nm and 409nm (denoting heme-iron containing ligninases) for fractions from the preparative DEAE anion exchange column and salt gradient used to fractionate the enzymes in a crude culture extract. (Reproduced widi permission from ref. 15. Copyright 1990 Springer-Verlag.)...

On-column UV absorbance detection is by far the most common method of detection in CE today. Many compounds of interest absorb light to some extent in the UV region without any chemical modification. Detector components are fairly robust and inexpensive, and little operator skill is required. For these reasons, most commercial CE instruments are equipped with a standard UV absorbance detector. However, as absorbance signals are directly proportional to the optical pathlength (Beer s Law), the 10-100 xm internal diameter of capillaries used in CE yield rather disappointing detection limits in the range of 10-5-10-7M (7). 

Equivalent width for optically-thin samples, k, L 1. For a column of absorbing gas in which the optical depth at the centre of the line is small compared to unity, k L exponential factor in equation (10.19) and to a good approximation v e have... 

Harada et al. started from preparing inclusion complexes by adding an aqueous solution of PEG bisamine (PEG-BA) to a saturated aqueous solution of a-CD at room temperature and then allowing the complexes formed to react with an excess of 2,4-dinitrofluorobenzene. They examined the product by column chromatography on Sephadex G-50, with DMSO as the solvent, and obtained the elution diagram shown in Fig. 46. They identified the first, second, and third fraction, respectively, as the desired product, i.e., a polyrotaxane, dinitrophenyl derivatives of PEG, and uncomplexed a-CD, by measurement of both optical rotation and UV absorbance at 360 nm for the first, UV absorbance at 360 nm for the second, and optical rotation for the third. 

Outside vapor deposition (OVD), in fiber optic fabrication, 11 140, 141 Outsourcing, of maintenance, 15 478 Ovalbumin, properties of standard, 3 836t Overaged precipitation, 13 502 Overall gas-phase height of a transfer unit (Hog), packed column absorbers, 1 52... 

Figure 25-20 Photodiode array ultraviolet detector for HPLC. (a) Dual-beam optical system uses grating polychromator, one diode array for the sample spectrum, and another diode array for the reference spectrum. Photodiode arrays are described in Section 20-3. (fc>) Reversed-phase chromatography (using C18-silica) of sample containing 0.2 ng of anthracene, with detection at 250 nm. Full-scale absorbance is 0.001. (c) Spectrum of anthracene recorded as it emerged from the column. [Courtesy Perkln-Elmer Corp.. Norwalk. Cl]...

From Rayleigh and schlieren optics, one could calculate cMwa, and hence one could calculate A (cMwa) at every r in the solution column of the ultracentrifuge cell and use the analysis used with the other methods (see Equation 76 and the discussion following it). This could also be done even if only one of the reactants had an absorption spectrum, since c = cA° + cB°. The other possibility is that the complex AnBm has a different absorption spectrum from the reactants, or that in the formation of AnBw some chromophoric groups are buried so that the absorbance of A and B represents a quantity proportional to cA and cB. In either case one could then calculate... 

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