Spectrophotometry, derivative

The sensitivity can, however, be improved if the technique of derivative spectrophotometry (Section 17.12) is employed. The development of inexpensive photoelectric colorimeters has placed this branch of instrumental chemical analysis within the means of even the smallest teaching institution. 

Deposit character of, (eg) 509 Deposition completeness of, 507 potentials of metals, 508 Derivative spectrofluorimetry 733 Derivative spectrophotometry 668 Derivatisation in chromatography, gas, 236 liquid, 228 in fluorimetry, 735 Desiccants 99 Desiccators 98 cooling of crucible in, 100 desiccants for, 99 Scheibler type, 99 uses of, 100 vacuum, 100... 

Ergun, E. et al.. Simultaneous determination of chlorophyll a and chlorophyll b by derivative spectrophotometry. Anal. Bioanal. Ghent., 379, 803, 2004. 

In conclusion, synthetic dyes can be determined in solid foods and in nonalcoholic beverages and from their concentrated formulas by spectrometric methods or by several separation techniques such as TEC, HPLC, HPLC coupled with diode array or UV-Vis spectrometry, MECK, MEECK, voltammetry, and CE. ° Many analytical approaches have been used for simultaneous determinations of synthetic food additives thin layer chromatography, " " derivative spectrophotometry, adsorptive voltammetry, differential pulse polarography, and flow-through sensors for the specific determination of Sunset Yellow and its Sudan 1 subsidiary in food, " but they are generally suitable only for analyzing few-component mixtures. 

Berzas Nevado, J.J. et ah. Simultaneous determination of tartrazine, riboflavine, curcumin and erythrosine by derivative spectrophotometry, Fresenius J. Anal. Chem., 350, 610, 1994. 

Bozdogan, A., Ozgur, U.M., and Koyuncu, L, Simultaneous determination of sunset yellow and Ponceau 4R in gelatin powder by derivative spectrophotometry and partial least-squares multivariate spectrophotometric calibration, Anal. Lett., 33, 2975, 2000. 

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

Vidotti, E.C., Rollemberg, M., and do Carmo E., Derivative spectrophotometry a simple strategy for simnltaneons determination of food dyes, Quim. Nova, 29, 230, 2006. 

Second-derivative spectrophotometry has been used to monitor the time-dependent production of cis,tmns-(Xmax 242 nm) and trans, tram- (Xmax 232 nm) diene conjugates of microsomal PUFAs following the exposure of rats to carbon tetrachloride (CCU) (Corongui et al., 1986). These signals have been postulated to be derived from mixtures of peroxidized substrates. Previous studies using chemical model systems have established that autoxidation of linolenic or arachidonic acid results in the production of cis, trans- and tmns, trawr-conjugated diene... 

It has proved to be very useful, providing both qualitative and quantitative information derived from mathematical processing of UV/VIS spectra. The principles of derivative spectrophotometry were discussed [15,16]. Obviously, derivatisation of spectra does not provide any additional information to that acquired during the measurement, but allows for easier interpretation. In particular, the possibility of resolving overlapping peaks makes derivative spectrophotometry a valuable tool for multicomponent analysis. Typically, derivative spectrophotometry is useful for the simultaneous determination of two additives in polymeric materials with very closely positioned absorption maxima. In quantitative analysis, derivative spectrophotometry leads to an increase in selectivity. 

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. 

Erk and Altun [24] used a ratio spectra derivative spectrophotometric method and a high performance liquid chromatographic method for the analysis of miconazole nitrate and metronidazole in ovules. The spectral method depends on ratio spectra first derivative spectrophotometry, by utilizing the linear relationship between substances concentration and ratio spectra first derivative peak amplitude. The ratio... 

Wrobel et al. [29] described a simple method for the determination miconazole in pharmaceutical creams, based on extraction and second-derivative spectrophotometry. In the presence of sodium lauryl sulfate (0.5%) and sulfuric acid (0.4 mol/L), the miconazole and internal standard (methylene blue) were extracted to 100 pL of methylene chloride. The organic phase was evaporated in the nitrogen stream and the dry residue was dissolved in methanol (1.5 mL). The analytical signal was obtained as the ratio between second-derivative absorbances measured at 236.9 nm... 

Onur and Dine [45] described four new spectrophotometric methods for simultaneous determination of niclosamide (I) and thiabendazole (II) in tablets and other binary mixture formulations. The method used picric acid for selective precipitation of (II) followed by determination of (I) by first-derivative spectrophotometry. 

Further enhancement in specificity has been achieved by the HPLC separation of the complex prior to measurement (Shih and Hu 1999). Other possible approaches are the extraction of malondialdehyde prior to the formation of the chromogen and/or derivative spectrophotometry. 

Talsky [1] has used higher order derivative Spectrophotometry to determine aniline in soil. 

Talsky [1] illustrated the practical use of higher-order derivative spectrophotometry in estimating pollutants in soils by detailed descriptions of the simultaneous estimation of aniline in waste water, phenol in soils and the study of nickel adsorbed on to bentonite powder. 

In this work, two methods for the determination of caffeine in energy drinks by derivative spectrophotometry and by partial least-squares multivariate spectropho-tometric calibration (PLS-1) are described. Proposed methods involve background correction methods that interferences from vitamins, taurin and food colours were minimized by treating the sample with basic lead acetate and NaHC03 for the arralysis of caffeine in energy drinks. 

In the first method, derivative spectrophotometry, the amplitudes in the first derivative spectra at 287 and 260 nm were selected to determine caffeine. The concentration range of application is 3-15 pg mL for caffeine. 

The determirration of caffeine has always been problematic with specific methods or modifications being required for specific foodstrrffs. The proposed derivative spectrophotometry and PLS-1 involve sample pretreatment with basic lead acetate. 

First-derivative spectrophotometry was used to identify chlorpromazine in the presence of other phenothiazines, while second derivative spectrophotometry enabled the direct determination of chlorpromazine in spiked blood samples [89], In addition, third derivative spectroscopy was used to determine chlorpromazine and its sulfoxide decomposition product in pharmaceutical dosage forms [90]. 

Galal et al. determined diloxanide furoate and metronidazole in two-component tablets using first (Di) and second (D2) derivative spectrophotometrie methods [17]. The methods were based on the direct measurement of diloxanide furoate in 0.1 N hydrochloric acid solution at 262 nm (Dj method) and at 248 nm (D2 method), without any interference from the co-existing component. The methods were applied for the determination of diloxanide furoate in the laboratory-made mixtures and in tablets, and the authors reported a relative standard deviation less than 2%. 

Daabees determined the drug and its degradation product by second (D2) and third (D3) derivative spectrophotometry [18]. The methods were based on measuring the D2 and D3 amplitudes at 260 and 270 nm, respectively, for analytes dissolved in 0.1 N hydrochloric acid. No interference with the degradation product was noted. 

Fourth-derivative spectrophotometry in the UV region can be used to assess the contents of aromatic amino acid residues and thus enable... 

The calibration curve was established for 4.2-69.0 fig/ml of atorvastatin by first derivative spectrophotometry, and the method showed no interference from the common pharmaceutical adjuvants [11]. 

The same modified reagent has also been used with effect in the analysis of terpenoids and other steroids, and especially for the anabolic steroids. These applications are mentioned only as a passing reference because, like cholesterol, the analytes are more readily determined using zero and/or first order derivative spectrophotometry. If there is one distinct advantage associated with CD detection it is that the 17-ketosteroids, which are major interferences to absorbance detection in the analysis of urine for anabolic steroids, do react with the loss of all CD activity. 

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