Spectrophotometric data

Long, J. R. Drago, R. S. The Rigorous Evaluation of Spectrophotometric Data to Obtain an Equilibrium Constant, /. Chem. Educ. 1982, 59, 1037-1039. 

I. Sunshine, CRC Handbook of Spectrophotometric Data of Drugs, CRC Press, Boca Raton, Fla., 1981. 

The three normal means of presenting the spectrophotometric data are described below by far the most common procedure is to plot absorbance against wavelength (measured in nanometres). The wavelength corresponding to the absorbance maximum (or minimum transmission) is read from the plot and is used for the preparation of the calibration curve. This point is chosen... 

The spectrophotometric data as a function of temperature in 2 M HCIO4 by Rabideau and Masters (114) are said by these authors to be equally well interpreted on the basis of the existence of both Pu02Cl+ and PuOpC j or of Pu02Cl+ only. However, evidence for the presence of Doth species is definitely found at y = 4 (112) and y = 2 (113). At y = 2 values of log e1(Pu02Cl+) =... 

The dimer U2(X1), U204, was detected by its absorption at 737 m/t. Analysis of spectrophotometric data using the rate law... 

Wetton and Higginson have briefly investigated the reaction between Fe(IlI) and Sn(II). Spectrophotometric data for the rate of disappearance of Fe(IlI) were obtained at 335 m/i. In the absence of substantial amounts of Fe(II) and Sn(lV) the kinetics in 1.0 M hydrochloric acid are of simple second order, indicating that Sn(II) is present as the monomeric species. The addition of Fe(ll) to the reacting system produces a pronounced retardation, the second-order plots showing curvature after 75 % reaction. The appropriate mechanism is... 

Maeder, M., Gampp, H. Spectrophotometric data redudion by eigenvedor analysis for equilibrium and kinetic smdies and a new method of fitting exponentials. Anal. Chim. Acta 1980, 122, 303-313. 

The kinetics were followed by measuring the increase in absorbance at 400 nm due to the formation of the p-nitrophenoxide anion in a tris buffer solution at pH 8.5. The substrate was used in excess over the free base catalyst, whose concentration was calculated from spectrophotometric data. 

Apparently similar flowstream universal buffers have been developed by Alibrandi and others [128,129] for assessing kinetic parameters, such as the pH-dependent hydrolysis of acetylsalicylic acid. The pH-time curves are not as linear as in the SGA system. Other reports of continuous flow pH gradient spectrophotometric data have been described, with application to rank-deficient resolution of solution species, where the number of components detected by rank analysis is lower than the real number of components of the system [130]. The linear pH-time gradient was established in the flowstream containing 25 mM H3PO4 by the continuous addition of 100 mM Na3P04. 

Gampp, H. Maeder, M. Zuberbiihler, A. D., General non-linear least-squares programfor the numerical treatment of spectrophotometric data on a single-precision game computer, Talanta 27, 1037-1045 (1980). 

Saurina, J. Hemandez-Cassou, S. Izquierdo-Ridorsa, A. Tauler, R., pH-gradient spectrophotometric data files from flow-injection and continuous flow systems for two- and three-way data analysis, Chem. Intell. Lab. Syst. 50, 263-271 (2000). 

Figure 6. Photodegradation rate data on Tinuvin-type UV stabilizers (A) UV-visible spectrophotometric data (B) FTIR data on PMMA films...

In an equilibrium study of the adsorption of molybdenum(VI) from aqueous solution onto activated carbon it has been found that the data are best explained in terms of an absorption model comprising the three species [HMo207] , Mo03(H20)3, and [HMo04] of which the dimer predominates by far (80). Computer treatment of potentiomet-ric (81) and spectrophotometric data (82) also indicated the possible existence of [HMo207] as a minor species in aqueous solution at low molybdenum concentration ( 2 X 104 Af). However, as its assumed stability region overlaps with several other polynuclear ions more direct evidence is needed before its existence can be accepted with certainty. 

IUPACC Commission on Spectrochemical and other Optical Procedures for Analysis Spectrophotometric Data for Colorimetric Analysis, London, Butterworth Publishers Ltd., 1963. 

Calculated from UWVIS spectrophotometric data, unless otherwise indicated. 

In addition to designing experiments to avoid the above complications, caution should be exercised in the work up of the data. The procedure we recommend for evaluating spectrophotometric data has been reported (26, 27). An improved method for selecting the best K i was subsequently reported (20). Adaptation of these equations to calorimetric (20) and magnetic resonance (23) experiments have also been reported. For the spectrophotometric experiment in which there is an overlap of the absorption band of the acid and the adduct it forms, the equation has the form ... 

FIGURE 2.21 Scatter plot of the sensorial descriptors and overall quality estimated by e-nose, e-tongue, and spectrophotometric data. Plots show predicted (O) and calculated ( ) versus experimental responses. The R , leave-one-out, and bootstrap values of each model are shown (reproduced from Buratti et al, 2007, with permission). 

Spectrophotometric data on some Ni(II) macrocyclic complexes are summarized in Table I. The maximum absorption of the square-planar Ni(II) complex with neutral azamacrocyclic ligand shifts to a longer... 

In addition to their use in pigment identification, spectrophotometric data can be used to determine the concentration of pigments in a plant ex-... 

Additional proof for the relation between indigo concentration and uptake of indigo by the fabric was obtained when the concentrations of indigo and dithionite were controlled. It can be seen clearly from the second section of Fig. 6.17 and Fig. 6.18 that if the concentration of indigo is kept constant, the quality and reproducibility of the dyed product improves remarkably. In addition, the spectrophotometric data results remain constant, indicating that a reproducible dye result is obtained for the fabric. 

The purpose of this Chapter is to review the recent literature on relevant basic concepts. The subject is discussed from three general points of view the spectrophotometric data, the visual appearance of a product, and the chemical structure and properties of the sugar s colorant. The structure of the colorant and the precursors in its formation are of particular concern. The discussion is limited to the interpretation of the trans-... 

Y/(X + Y + Z), which are equal to x and y, respectively, are called chromaticity coordinates z can also be calculated, but no more information is obtained. The tristimulus values, X, Y, and Z, can be calculated from spectrophotometric data and then be used for calculating the chro-... 

In an optical study of sugar products in solution, it is essential to differentiate between the color, the spectrophotometric data, and the evaluation of the colorant. The term color should be reserved solely as an expression of visual appearance. In addition, a uniform nomenclature for spectrophotometric data should be adopted by the sugar industry. 

Spectrophotometric data for the stability constants of complexes of Me3SnCl with substituted pyridine JV-oxides in acetonitrile show (76) that these constants correlate linearly with the [Pg.81]

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