Spectrophotometry applications

L13. Lorber, A., Cohen, R. L., Chang, C. C., and Anderson, H. E., Gold determination in biological fluids by atomic absorption spectrophotometry application to chrysotherapy in rheumatoid arthritis patients. Arthritia Rheum. II, 170-177... 

FI. El Khorassani, Characterization of Industrial Effluents by UV Spectrophotometry Application to Petrochemical Industry. PhD thesis, University of Aix-Marseille I, (1998). 

Spectrophotometry, application to catalytic systems, 14, 115 Spectroscopy, electronic, of adsorbed gas molecules, 15, 227... 

Concise reviews of pertinent aspects of thermodynamics, kinetics, spectrophotometry, etc. are presented prior to developing applications of these topics to polymers. 

Methods are described for determining the extent to which original natural color is preserved in processing and subsequent storage of foods. Color differences may be evaluated indirectly in terms of some physical characteristic of the sample or extracted fraction thereof that is largely responsible for the color characteristics. For evaluation more directly in terms of what the observer actually sees, color differences are measured by reflectance spectrophotometry and photoelectric colorimetry and expressed as differences in psychophysical indexes such as luminous reflectance and chromaticity. The reflectance spectro-photometric method provides time-constant records in research investigation on foods, while photoelectric colorimeters and reflectometers may prove useful in industrial color applications. Psychophysical notation may be converted by standard methods to the colorimetrically more descriptive terms of Munsell hue, value, and chroma. Here color charts are useful for a direct evaluation of results. 

Application of Spectrophotometry to the Study of Catalytic Systems H. P. Leftin and M. C. Hobson, Jr. 

Analytical applications of substituted cinnamohydroxamic acids in spectrophotometry and solvent extraction of metal ions. Y. K. Agrawal and R. K. Jain, Rev. Anal. Chem., 1982, 6,49-64 (71). 

Because of peak overlappings in the first- and second-derivative spectra, conventional spectrophotometry cannot be applied satisfactorily for quantitative analysis, and the interpretation cannot be resolved by the zero-crossing technique. A chemometric approach improves precision and predictability, e.g., by the application of classical least sqnares (CLS), principal component regression (PCR), partial least squares (PLS), and iterative target transformation factor analysis (ITTFA), appropriate interpretations were found from the direct and first- and second-derivative absorption spectra. When five colorant combinations of sixteen mixtures of colorants from commercial food products were evaluated, the results were compared by the application of different chemometric approaches. The ITTFA analysis offered better precision than CLS, PCR, and PLS, and calibrations based on first-derivative data provided some advantages for all four methods. ... 

El-Sayed, A.A.Y. and El-Salem, N.A., Recent developments of derivative spectrophotometry and their analytical applications. Anal. Sci., 21, 595, 2005. 

Applications Applications of UV/VIS spectrophotometry can be found in the areas of extraction monitoring and control, migration and blooming, polymer impregnation, in-polymer analysis, polymer melts, polymer-bound additives, purity determinations, colour body analysis and microscopy. Most samples measured with UV/VIS spectroscopy are in solution. However, in comparison to IR spectroscopy additive analysis in the UV/VIS range plays only a minor role as only a limited class of compounds exhibits specific absorption bands in the UV range with an intensity proportional to the additive concentration. Characteristic UV absorption bands of various common polymer additives are given in Scheirs [24],... 

Among the spectroscopic methods applicable to polysaccharides, u.v. spectrophotometry is of little value for characterizing heparin, whose main, electronic chromophore (the C02 group) displays a band at 220 nm, that is, in a region where all glycosaminoglycans absorb (also through their N-acetyl chromophores), and where minor proportions of unsaturated or aromatic contaminants cause serious interference.77 With pure heparin preparations, the carboxylate chromophore is most useful for chiroptical measurements, and a semi-quantitative evaluation of the extent of N-acetylation of 2-amino-2-deoxy-D-glucose residues is also possible.78... 

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

The PG models 9.1 and 10.1 show similar trends as indicated by PA, but the effects are somewhat muted. The increase in PG from 0.6% to 1.1% causes the permeabilities of weak bases to decrease and membrane retentions to increase, with many bases showing R > 60%. Many molecules were not detected in the acceptor compartments by UV spectrophotometry after 4 h permeation times (Table 7.7). These properties of the PG system make it less attractive for high-throughput applications than the other two-component models. 

Goger and Gokcen [19] developed a quantitative method for the determination of miconazole in cream formulations that contain benzoic acid as preservative by second order derivative spectrophotometry. The procedure was based on the linear relationship in the range 100—500 pg/mL between the drug concentration and the second-derivative amplitudes at 276 nm. Results of the recovery experiments performed on various amounts of benzoic acid and the determination of miconazole in cream confirmed the applicability of the method to complex formulations. 

Test 2 Examine by infrared absorption spectrophotometry, according to the general procedure (2.2.24), comparing with spectrum obtained with primaquine diphosphate Chemical Reference Substance (CRS). Examine the substance as discs prepared as follows dissolve separately 0.1 g of primaquine diphosphate and the reference substance in 5 mL of water R, add 2 mL of dilute ammonia R and 5 mL of chloroform R and shake dry the chloroform layer over 0.5 g of anhydrous sodium sulfate R prepare a blank disc using about 0.3 g of potassium bromide R, apply dropwise to the disc 0.1 mL of the chloroform layer, allowing the chloroform to evaporate between applications dry the disc at 50 °C for 2 min. 

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. 

Hoather RC (1953) Applications of Spectrophotometry for the Examination of Water Proceedings of the Society of Water Treatment and Examination 2 9... 

Atienza et al. [657] reviewed the applications of flow injection analysis coupled to spectrophotometry in the analysis of seawater. The method is based on the differing reaction rates of the metal complexes with 1,2-diaminocycl-ohexane-N, N, N, A/Metra-acetate at 25 °C. A slight excess of EDTA is added to the sample solution, the pH is adjusted to ensure complete formation of the complexes, and a large excess of 0.3 mM to 6 mM-Pb2+ in 0.5 M sodium acetate is then added. The rate of appearance of the Pbn-EDTA complex is followed spectrophotometrically, 3 to 6 stopped-flow reactions being run in succession. Because each of the alkaline-earth-metal complexes reacts at a different rate, variations of the time-scan indicates which ions are present. 

Applications of NMR, ESR, thermal analysis, spectrophotometry, gas chromatography, and GC-MS to humic and fulvic acid analysis have been reviewed by Schnitzer [452]. 

The carrier stream is merged with a reagent stream to obtain a chemical reaction between the sample and the reagent. The total stream then flows through a detector (Fig. 1.1 (b)). Although spectrophotometry is the commonly used detector system in this application, other types of detectors have been used, namely fluorometric, atomic absorption emission spectroscopy and electrochemical, e.g. ion selective electrodes. 

Fluorometry and absorption spectrophotometry are competing techniques in the sense that both analyze for molecular species and complex ions. Each offers its own advantages and disadvantages. As stated above, the number of chemical species that exhibit fluorescence is very limited. However, for those species that do fluoresce, the fluorescence is generally very intense. Thus we can say that while absorption spectrophotometry is much more universally applicable, fluorometry suffers less from interferences and... 

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