Spectrophotometry, solution

Only slightly less accurate ( 0.3—0.5%) and more versatile in scale are other titration techniques. Plutonium maybe oxidized in aqueous solution to PuO " 2 using AgO, and then reduced to Pu" " by a known excess of Fe", which is back-titrated with Ce" ". Pu" " may be titrated complexometricaHy with EDTA and a colorimetric indicator such as Arsenazo(I), even in the presence of a large excess of UO " 2- Solution spectrophotometry (Figs. 4 and 5) can be utilized if the plutonium oxidation state is known or controlled. The spectrophotometric method is very sensitive if a colored complex such as Arsenazo(III) is used. Analytically usehil absorption maxima and molar absorption coefficients ( s) are given in Table 10. Laser photoacoustic spectroscopy has been developed for both elemental analysis and speciation (oxidation state) at concentrations of lO " — 10 M (118). Chemical extraction can also be used to enhance this technique. 

Solution prepregging, 20 284-285 Solution processing, 14 80 Solution process, of ethylene-propylene polymer manufacture, 10 708-710 Solution properties of lignin, 15 13 of polyampholytes, 20 479 ofVDC copolymers, 25 703-706 Solution spectrophotometry, 9 232 Solution spinning... 

Billmeyer FW Jr, Kumar R, Saltzman M (1981) Identification of organic colorants in art objects by solution spectrophotometry pigments. J Chem Educ 58 307-313. 

Solution spectrophotometry in the visible and ultraviolet can he used to determine the nature of dyes used to color textiles of archaeological or historical importance. The curves obtained are compared with those from solutions of known materials. The method requires dyeings made with known natural dyes from the region of interest. Collections of such materials have been obtained from Peru, The principle red dyes of Peru can be identified by means of a single solution curve. Blue, from indigo, can easily be distinguished from the purple dibromoindigo obtained from marine molluscs. Yellow dyes are more difficult to identify and require, in most cases, curves in more than one solvent. 

This laboratory has examined the many techniques which are available. These range from the classic organic analytical methods of the 19th century through chemical spot tests, solution spectrophotometry, infrared, and other optical spectroscopic techniques through mass spectrometry. Thin-layer chromatography is, by itself, a separation technique which allows identification of the separated components by some appropriate technique. In many cases the patterns obtained may be sufiicient for identification, and in the hands of such workers as... 

To our knowledge, the first use of solution spectrophotometry to study dyes of archaeological interest was made by Fester and his associates in their work in the colorants of Paracas (7,8). The method requires the preparation of solutions—obtained by stripping the dye from the fiber... 

The second problem associated with solution spectrophotometry is our need for samples of known origin. For dyes from plants this requires, in addition to complete botanical information, samples of yarn dyed under known conditions from these plants. While the dyed yarn cannot contain any material which was not in the plant (except for mordants which may be used), there is much in the plant which may alter a curve but which will not dye the plant. The same is true of insect or other animal material. 

In summary, we believe, based on almost 30 years of experience with the technique of colorant identification using solution spectrophotometry, that it is a satisfactory, simple, and rapid technique for identifying the natural dyes used in early America. As we complete our file of reference material and as we obtain samples of known provenence, we can attempt to compile lists of dye usage as related to time and place in Precolumbian America. 

Chemical solutions spectrophotometry spectrofluorimetry ceric-cerous, organic acids, ethanolchlorobenzen e... 

Thus far, we have only considered the absorption of energy by electronic and molecular transitions. When we make spectral measurements, it is necessary to consider other optical processes. This is particularly important for solution spectrophotometry. 

These occur at the U V end of the usual range for solution spectrophotometry, and in general have lower extinction coefficients than O O transitions. The band due to an o transition is removed... 

Traditionally, UV-Visible spectra have been obtained in solution. Quantitative analysis is obtained based on the Beer-Lambert law. For quantitative analysis by solution spectrophotometry the colorant must be completely dissolved and other components in the sample must not interfere with the determination. In addition, purified standards containing known amounts of the pigment being determined are required. Since HPOPs are highly insoluble, strong organic solvents or concentrated sulfuric acid are usually employed in order to effect complete dissolution of the pigment. 

For quantitative analysis by solution spectrophotometry the colorant must be completely dissolved and other components in the sample must not interfere with the determination. In addition, purified standards containing the known amount of pigment being determined are required. 

In addition to the analysis of solutions, spectrophotometry has also found unique applications in the nondestructive determination of doped impurities in single crystals such as, for example, the determination of chromium in ruby. ... 

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