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Derivative Spectrophotometry (derivative + spectrophotometry)
Selected AbstractsSimultaneous determination of metronidazole and spiramycin in bulk powder and in tablets using different spectrophotometric techniquesDRUG TESTING AND ANALYSIS, Issue 1 2010Fatma I. Khattab Abstract Metronidazole (MZ) is an anti-infective drug used in the treatment of anaerobic bacterial and protozoa infections in humans. It is also used as a vetinary antiparasitic drug. Spiramycin (SP) is a medium-spectrum antibiotic with high effectiveness against Gram-positive bacteria. Three simple, sensitive, selective and precise spectrophotometric methods were developed and validated for the simultaneous determination of MZ and SP in their pure form and in pharmaceutical formulations. In methods A and B, MZ was determined by the application of direct spectrophotometry and by measuring its zero-order (D0) absorption spectra at its ,max = 311 nm. In method A, SP was determined by the application of first derivative spectrophotometry (D1) and by measuring the amplitude at 218.3 nm. In method B, the first derivative of the ratio spectra (DD1) was applied, and SP was determined by measuring the peak amplitude at 245.6 nm. Method C entailed mean centring of the ratio spectra (MCR), which allows the determination of both MZ and SP. The methods developed were used for the determination of MZ and SP over a concentration range of 5,25 µg ml,1. The proposed methods were used to determine both drugs in their pure, powdered forms with mean percentage recoveries of 100.16 ± 0.73 for MZ in methods A and B, 101.10 ± 0.90 in method C, 100.09 ± 0.70, 100.02 ± 0.88 and 100.49 ± 1.26 for SP in methods A, B and C, respectively. The proposed methods were proved using laboratory-prepared mixtures of the two drugs and were successfully applied to the analysis of MZ and SP in tablet formulation without any interference from each other or from the excipients. The results obtained by applying the proposed methods were compared statistically with a reported HPLC method and no significant difference was observed between these methods regarding both accuracy and precision. Copyright © 2010 John Wiley & Sons, Ltd. [source] Effect of dietary oregano oil and , -tocopheryl acetate supplementation on iron-induced lipid oxidation of turkey breast, thigh, liver and heart tissuesJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 9-10 2003G. Papageorgiou Summary Twenty-five 12-week-old turkeys randomly divided into five groups were given a basal diet, or a basal diet supplemented with 200 mg , -tocopheryl acetate/kg, or 100 mg oregano oil/kg or 200 mg oregano oil/kg, or 100 mg oregano oil plus 100 mg , -tocopheryl acetate/kg diet, for 4 weeks prior to slaughter. Breast, thigh, liver and heart tissues were subjected to iron-induced lipid oxidation, the extent of which was determined by third-order derivative spectrophotometry. Results showed that dietary oregano oil at the inclusion level of 200 mg oregano oil/kg diet was more effective in delaying lipid oxidation compared with the inclusion level of 100 mg/kg, but equivalent to the inclusion of 200 mg , -tocopheryl acetate/kg diet, which in turn was inferior to the combined inclusion of 100 mg oregano oil plus 100 mg , -tocopheryl acetate/kg, which was superior to all dietary treatments. Thigh tissue was more susceptible to oxidation than breast tissue, although it contained , -tocopherol at higher concentrations. Also, lipid oxidation in heart was relatively high, although it contained the highest , -tocopherol levels. This indicates that tissue , -tocopherol is one important factor influencing the level of lipid oxidation, but the distribution of lipids, iron and oregano oil in tissues must also be taken into consideration. Tissue , -tocopherol levels responded to dietary intake of 30,200 mg , -tocopheryl acetate/kg in the order heart > liver > thigh > breast. Breast, thigh and heart tissues from the oregano groups presented significantly (p < 0.05) higher levels of , -tocopherol compared with the control, the increase being positively correlated with the supplementation level. The increased levels of , -tocopherol in these tissues indicated that the dietary oregano oil exerted a protective action on , -tocopherol. [source] COMPARATIVE STUDY OF MICROENCAPSULATION OF CASEIN HYDROLYSATES IN LIPOSPHERES AND LIPOSOMESJOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2004HARRIMAN ALEY MORAIS The encapsulation in lipospheres and in liposomes was used with the aim of masking the bitterness of casein hydrolysates for dietetic of pharmaceutical purposes. Papain was used for preparing three casein hydrolysates, employing different temperatures and E:S ratios. The percentage of encapsulation of these preparations was measured by second derivative spectrophotometry (SDS). Lipid oxidation over a period of 60 days, was followed by quantifying the 2-thiobarbituric acid reactive substances (TBARS). Other analysis were performed for characterizing these vesicles, including the sensory evaluation and the measure of hydrophobicity. The results showed that these two encapsulation systems were equally efficient in reducing the hydrophobicity and the bitterness of casein hydrolysates. SDS was a useful tool in the characterization of these preparations. It is a quick and relatively low-cost method, and indicated that the encapsulation rate in lipospheres (65%) was higher than in liposomes (59%). The TBARS method revealed the chemical stability of these preparations over the period of study (60 days). [source] Papain hydrolysates of casein: molecular weight profile and encapsulation in lipospheresJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2004Cristiane MS Barbosa Abstract Some reaction parameters were tested in the hydrolysis of casein by papain, in order to prepare hydrolysates with high oligopeptide contents, for either dietetic or pharmaceutical purposes. Five casein hydrolysates were prepared and then fractionated by size-exclusion HPLC. The rapid correct fraction area method was used for quantifying peptides and free amino acids. Among the five reaction conditions tested, three produced similar peptide profiles. However, the use of a temperature of 37°C and an E:S ratio of 2% is probably the most economical condition for use in large-scale manufacture. With the aim of masking the bitterness of these preparations, a new method, based on the encapsulation in lipospheres, was used. Also, second derivative spectrophotometry was used for the first time to measure the extent of encapsulation of protein hydrolysates, which changed from 50% to 83%. Moreover, the efficiency of this system was evaluated by analysing other parameters, which showed a reduction of hydrophobicity and bitterness of all samples, as well as good chemical stability during 60 days of storage under refrigeration. The electron microscopical analysis of liposheres showed an average size around 5.0 ± 1.0 µm. Copyright © 2004 Society of Chemical Industry [source] | ||||||||||