Ultraviolet analysis

Residual aromatic ether concentrations are determined from the absorbance at 278 mfi of the crude reduction products in methanol solution. Steroidal ether concentrations of 1 mg/ml are employed. The content of 1,4-dihydro compound is determined, when possible, by hydrolysis to the a, -unsaturated ketone followed by ultraviolet analysis. A solution of the crude reaction product (usually 0.01 mg/ml cone) in methanol containing about 1/15 its volume of water and concentrated hydrochloric acid respectively is kept at room temperature for 2 to 4 hr. The absorbance at ca. 240 mfi is measured and, from this, the content of 1,4-dihydro compound can be calculated. Longer hydrolysis times do not increase the absorbance at 240 mp.. 

Piperidine obtained from Eastman Kodak was fractionated through a 90-cm. column packed with glass helices, and the fraction distilling at 105° was used for this work. This material contained approximately 0.36 wt.% of pyridine as indicated by vapor phase chromatography and ultraviolet analysis. 

Quantitative ultraviolet analysis of griseofulvin may be performed by comparison to a Reference Standard. The ultraviolet absorbance is described in Section 2.04 and Figure 5. 

Liquid chromatography Visual inspection of eluting fractions Ultraviolet analysis of eluted fractions... 

Lee et al. [74] used UV spectroscopy to identify polyaromatic hydrocarbons in river sediments. The procedure involved the collection of sediments, air drying in the dark, sieving, and extraction for organic content. This was followed by column chromatography (silica gel with cyclohexane as eluent), followed by a second chromatographic step with Sephadex LH-20 and propan-2-ol as eluent. The eluate was then concentrated under vacuum and prepared for ultraviolet analysis. 

Corbit, R. M., Ferreira, J. F. S., Ebbs, S. D., and Murphy, L. L. (2005). Simplified extraction of ginsenosides from American ginseng (Panax quinquefoUus L.) for high-performance liquid chromatography-ultraviolet analysis. /. Agric. Food Chem. 53, 9867-9873. 

Phenolic Ethers. Substitution of the phenolic proton by an alkyl group results in a spectrum which closely resembles that of the neutral species of the parent phenol (4). The pesticides that fall into this group are the phenoxy compounds. Table VI shows the Amax values of some important pesticide ethers. The alkyl phenyl ethers do not exhibit a bathochromic shift with pH change into the alkaline range because there is no free phenolic proton to be lost and no charged anion is formed. This represents an important avenue in ultraviolet analysis, in which small amounts of free phenols may be determined in the presence of an excess of the corresponding phenolic ether. Figure 4 shows the spectrum of 2,4-D and its parent phenol, 2,4-dichlorophenol. In an alkaline medium. 

The ultraviolet analysis for erythromycin estolate is basically that described by Kuzel e t a 1. 5 Alkali, buffer, and reference standard solutions must be prepared prior to assaying. 

Ultraviolet examination of the sulfur types indicates broad overlapping bands of relatively low intensity in the extreme lower end of the spectrum which makes ultraviolet analysis impractical. 

Isopropamlde is found in dosage forms both alone and in combination with primary and tertiary amines. Assay methods Include ultraviolet analysis after extraction of Interfering amines and treatment with an anionic exchange resin, and colorimetric analysis by ion-paring with acid dyes and extraction of the complex Into an organic solvent. 

Quantitative ultraviolet analysis of clofazimine has been performed, in a range of aqueous and nonaqueous media, at 280nm (Canavan et al., 1986 O Driscoll et al., 1990a,b), and colorimetrically at 482nm (Quigley et al., 1990). 

L.H. Garcia-Rubio, N. Ro, and R. D. Patel, Ultraviolet Analysis of Benzoyl Peroxide Initiated Styrene Polymerizations and Copolymerizations I. Macromolecules, (1984), 17, 1998-2005. 

Gas-liquid chromatography, when combined with ultraviolet analysis 556) and additionally with nuclear magnetic resonance spectroscopy (557), has been developed into a powerful tool for the characterization of sub-milligram quantities of coumarins from plant extracts. Free hydroxycoumarins are better analyzed as their trimethylsilyl ethers 203) though a new technique 206) has permitted the gas chromato-graphic-mass spectrometric analysis of coumarins avoiding the necessity of forming derivatives. 

Cepha- mycin Empirical formula Molecular weight Ultraviolet analysis Amino acid analysis (pmoles/mg) Circular dichroism. Cotton effect ... 

Fig. 5. The automatic chromatographic fraction

Albarino demonstrated the feasibility of quantitative ultraviolet analysis of Irganox 1010 antioxidant in polyethylene film at temperatures above the polymer melting point where the crystallites, which account for much of the scattering, are eliminated. 

The Food and Drug Administration have written numerous articles pertinent to the spectrophotometric analysis of certifiable dyes. Examples are the identification of azo dyes by ultraviolet analysis of their reduction products the ultraviolet determination of sul-fonated naphthalene intermediates in certifiable coal tar colors the ultraviolet analysis of commercial ethylbenzylaniline sulfonic acid... 

Vanillin pH effects in ultraviolet analysis Sugar, and uronic acids ultraviolet spectra [ ] ultraviolet method using o-aminodiphenyl applied to 22 sugars... 

This class of cascade polymers was termed Micellanes due to the obvious topological resemblance of the resulting molecules to globular micelles as well as their ability to function as a micelle. The micellar characteristics of the polytetramethylammonium salt of 23 were investigated via ultraviolet analysis... 

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