Spectrophotometry ultraviolet

Second derivative ultraviolet spectroscopy is a simple yet powerful technique for highlighting the fine structure of spectral curves. It involves calculating the second derivative of a spectrum with respect to wavelength and plotting the derivative rather than the spectrum itself. Second derivative absorbance spectra of lignin model compounds, milled wood lignins and lignosulfonates have been published (Lin 1982). 

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Optical methods of analysis are dependent either upon (i) measurement of the amount of radiant energy of a particular wavelength absorbed by the sample, or (ii) the emission of radiant energy and measurement of the amount of energy of a particular wavelength emitted. Absorption methods are usually classified according to the wavelength involved as (a) visible spectrophotometry (colorimetry), (b) ultraviolet spectrophotometry, and (e) infrared spectrophotometry. 

This exercise provides the opportunity of examining the absorption spectra of typical aromatic hydrocarbons and of investigating the possibility of analysing mixtures of hydrocarbons by ultraviolet spectrophotometry. 

Luchkevich et al. (1986, Table 6) demonstrated that for the three isomeric nitro-benzenediazonium ions and their (Z)-diazohxydroxides the acidity constants can be determined by ultraviolet spectrophotometry, by potentiometry, from the kinetics of reaction with hydroxide ions, from the (Z) (E) isomerization kinetics, and from the kinetics of azo coupling reactions. These independent methods gave surprisingly consistent results. ... 

A. J. Son and J. Chakravarty. Analysis of residual corrosion inhibitors by fluorescence and ultraviolet spectrophotometry. In Proceedings Volume. 51 St Annu NACE Int Corrosion Conf (Corrosion 96) (Denver, CO, 3/24-3/29), 1996. 

Several collaborating laboratories (usually five participating laboratories) test the proposed substance using a variety of techniques. The relative reactivity or relative absorbance of the impurities present in a substance must be checked when a nonspecific assay method is employed, e.g. by colorimetry or ultraviolet spectrophotometry. It is particularly important to quantify the impurities when a selective assay is employed. In such a case, it is best to examine the proposed substance by as many methods as practicable, including, where possible, absolute methods. For acidic and basic substances, titration with alkali or acid is simple but other reactions which are known to be stoichiometric may be used. Phase solubility analysis and differential scanning calorimetry may also be employed in certain cases. 

As active substances are separated and purified they are characterized by a combination of spectroscopic analyses and chemical correlations. Particularly useful spectroscopic analysis techniques are nuclear magnetic resonance (proton and carbon), mass spectrometry and Infra-red and ultraviolet spectrophotometry. 

Jatlow, P., Ultraviolet spectrophotometry of theophylline in plasma in the presence of barbiturates, Clin. Chem., 21,1518,1975. 

Spectrophotometic identification of elastomer or pyrolyzate Specific gravity Percent ash where applicable Ultraviolet spectrophotometry of extracts... 

Xue et al. [30] prepared a vaginal suppository formulation containing miconazole nitrate and determined its content by P-matrix ultraviolet spectrophotometry. The production of the suppository was finished with melting by the excipient of glyceryl esters fatty acid of artificial synthesis. Quantitative assay was conducted with a P-matrix ultraviolet spectrophotometer. The suppository was smooth and met the clinical requirement of vaginal disease treatment. The method of assay was accurate. 

The Department of the Environment UK [155] has described a number of alternative methods for the determination of total oxidised nitrogen (nitrate and nitrite) in aqueous solution, while specific methods for nitrate and nitrite are also included. Among the methods for total oxidised nitrogen, one is based on the use of Devarda s alloy for reduction of nitrate to ammonia, and another uses copperised cadmium wire for reducing nitrate to nitrite, which is determined spectrophotometrically. Nitrate may also be determined spectrophotometrically after complex formation with sulfosalicylic acid or following reduction to ammonia, the ammonia is eliminated by distillation and determined titrimetrically. Other methods include direct nitrate determination by ultraviolet spectrophotometry, measurements being made at 210 nm, and the use of a nitrate-selective electrode. Details of the scope, limits of detection, and preferred applications of the methods are given in each case. 

Cuvettes used for UV-VIS spectrophotometry must be transparent to all wavelengths of light for which it is used. If visible light is used, the material must ideally be completely clear and colorless, which means that inexpensive materials, such as colorless plastic and ordinary colorless glass, are perfectly suitable. A case of 500 plastic 1-cm-square cuvettes may cost as little as 50. However, ordinary colorless glass and plastic are not transparent to light in the ultraviolet region. For ultraviolet spectrophotometry, the cuvettes must be made of quartz, which is more expensive. A matched set of two cuvettes to be used in a doublebeam spectrophotometer may cost as much as 400. 

The complex formation between 2,4,6-trinitrophenol and the acetate ion in acetic acid solution (14) has been investigated by ultraviolet spectrophotometry (Clark et al., 1988a). The equilibrium constant at 298 K was found to have values of 34.8 and 41.7dm in acetic acid and in acetic acid-OD, respectively. From the measured value of cp = 0.58 for the fractionation factor for the solvated acetate ion under these conditions, the result q> 0.7 was deduced for the fractionation factor of the intermolecularly hydrogen-... 

Olesen, 0. V., Determination of phenobarbital and phenytoin in serum by ultraviolet spectrophotometry. Scand. J. Clin. Lab. Invest. 20, 63-69 (1967). 

High-Performance Liquid Chromatography-Ultraviolet Spectrophotometry. 16... 

Dao, L., Friedman, M. (1992). Chlorogenic acid content of fresh and processed potatoes determined by ultraviolet spectrophotometry. J. Agric. Food Chem., 40, 2152-2156. 

Edwards, L. J. (1950), The hydrolysis of aspirin. A determination of the thermodynamic dissociation constant and a study of the reaction kinetics by ultraviolet spectrophotometry, Trans. Faraday Soc., 46,723-735. 

Analytical Procedures. Figures for conversion are based on a method in which the graft copolymer was dissolved in o-dichlorobenzene and residual styrene monomer was determined by ultraviolet spectrophotometry. 

Photolysis studies of alkyl nitrites in the vapor phase has been limited to the verification of the presence of a nitroso dimer moiety among the products by ultraviolet spectrophotometry. The principal product of photolysis of butyl nitrite in the vapor phase is the trans-isomer of the dimer of nitrosomethane43 86 87 281 286 the reaction has been explained by a mechanism involving fragmentation of alkoxy-radicals. 

Haase, G. and Dunkley, W. L. 1969A. Ascorbic acid and copper in linoleate oxidation. I. Measurement of oxidation by ultraviolet spectrophotometry and the thiobarbituric acid test. J. Lipid Res. 10, 555-560. 

Corongiu, F.P. and Banni, S. 1994. Detection of conjugated dienes by second derivative ultraviolet spectrophotometry. Methods Enzymol. 233 303-310. 

IUPAC (International Union of Pure and Applied Chemistry). 1987b. Method 2.505. Evidence of purity and deterioration from ultraviolet spectrophotometry. In Standard Methods for the Analysis of Oils, Fats and Derivatives, 7th ed. (C. Paquot and A. Hautfenne, eds.) pp. 212-213. Blackwell Scientific. Palo Alto, Calif. 

S Delhaye, J Landry. High-performance liquid chromatography and ultraviolet spectrophotometry for quantitation of tryptophan in barytic hydrolysates. Anal Biochem 159 175-178, 1986. 

The same type of substrates may also serve for ultraviolet spectrophotometry, since acyl thiocholines show a maximum at 226 fi. In practice, it is more convenient to follow the change in optical density at about 250 y 12). The method, which works only with purified enzymes, measures substrate concentrations of 5 X 10-6 M. 

GFAAS = graphite furnace (flameless) atomic absorption spectroscopy TLC = thin layer chromatography HFP-AES = high frequency plasma-atomic emission spectroscopy NAA = neutron atomic analysis ICP-AES = inductively coupled plasma-atomic emission spectroscopy AAS = atomic absorption spectrometry GSE = graphite spectroscopic electrode UV = ultraviolet spectrophotometry PD = photodensitometer and (3,5-diBr-PADAP) = 2(-3,-5-dibromo-2-pyridylazo)-5- diethyl-ami nophenol. 

Solid Phase Extraction Thermal Conductivity Detector Ultraviolet (Spectrophotometry)... 

Ultraviolet Spectrophotometry Pentazocine can be determined in pentazocine hydrochloride tablets by a UV spectral method. The sample is extracted with sulfuric acid, basified, extracted with ether and back-extracted into 1 in 70 dilute sulfuric acid. The absorbance of the solution in 0.5 N H2SO1L is determined at 278 nm and compared to that of the standard preparation. A cation exchange column isolation method can be utilized to determine pentazocine in pentazocine lactate injection. Pentazocine is eluted from the column with methanol 6 N HC1 (1 1). Sample absorbance is read at 278 nm and compared to a pentazocine standard at approximately 120-w.g/ mL (3). 

Column chromatography has been applied to separate and analyse a mixture of salicylamide and acet-minophen in tablets and capsules (1+9)- Strongly acidic and basic celite columns are used to separate acetaminophen and salicylamide respectively. Quantitation is performed using ultraviolet spectrophotometry. 

Solvents for Ultraviolet Spectrophotometry Ultraviolet Spectra of Common Liquids Transmittance-Absorbance Conversion Correlation Table of Ultraviolet Active Functionalities Woodward s Rules for Bathochromic Shifts... 

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