PubMed · 2196844
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O V Calubiran, E Zackson, B Cunha. 1990. Group B Streptococcus hemorrhagic tonsillopharyngitis.. https://doi.org/10.1016/s0196-0644(05)81592-6
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Derivative spectrophotometry (ratio-spectra 1st- and 2nd-derivative and zero-crossing 2nd-derivative techniques) was applied for the determination of some cephalosporins in two component mixtures. Cefotaxime sodium salt (C(16)H(16)O(7)N(5)S(2)Na) and cefadroxil monohydrate (C(16)H(17)N(3)O(5)S.H(2)O) were examined. In all procedures, the calibration plots are linear up to 43 microg/ml of each antibiotic, with r ranging from 0.9997 to 0.9999. In the ratio-spectra method, the measurements were taken at 239.5 and 291.5 nm (cefotaxime, 1st-derivative), 238 and 283 nm (cefadroxil, 1st-derivative), 284 and 303 nm (cefotaxime, 2nd-derivative), and 229.5 and 245.5 nm (cefadroxil, 2nd-derivative). Detection limits at P=0.05 level of significance, calculated by a statistical treatment of calibration data, ranged from 0.15 to 0.58 microg/ml. LOD and LOQ ranged, respectively, from 0.19 to 0.51 and from 0.63 to 1.70 microg/ml. By the zero-crossing 2nd-derivative method, lines of regression are linear at 257 and 279 nm (cefotaxime) and 242 and 296 nm (cefadroxil). Detection limits from 0.28 to 0.51 microg/ml. LOD and LOQ from 0.27 to 0.41 and from 0.90 to 1.37 microg/ml, respectively. All the samples were tested for stability in solution and in the course of actual analysis, up to 80 h from their preparation. The developed derivative spectrophotometric methods were applied to synthetic mixtures and the RSD values ranged between 0.05 and 1.35% (ratio-spectra technique) and 0.01 and 1.07% (zero-crossing technique). The methods were also applied to vials and tablets for these drugs. The recoveries obtained were between 100.9 and 102.4% (ratio-spectra) and between 99.8 and 102.0% (zero-crossing). The procedures are simple, rapid, and did not require any preliminary separation or treatment of the samples. Instrumentation commonly available was utilised. The cephalosporins analysed are frequently used antibiotics of relevant clinical and pharmacological importance; hence this work would be of interest for the readers of journals devoted to pharmaceutical and biomedical analysis.
A flow-injection spectrophotometric method is described for the determination of cefadroxil (I) and cefotaxime (II). The method is based on the hydrolysis of the cephalosporin with sodium hydroxide whereby the sulfide ion is produced. The latter is allowed to react with N,N-diethyl-p-phenylenediamine sulfate (N,N-DPPD) and Fe (III), and the blue color produced is measured at 670 nm (method A). Linear calibration graphs are obtained in the range 36.34-109.2 and 95.48-477.4 microgml(-1) for I and II, respectively. The experimental limits of detection (three times the noise signal) are 0.036 and 0.048 microgml(-1) for I and II, respectively. The total flow-rate is 5.3 ml min(-1) for both drugs. Alternately, the sulfide ion produced is allowed to react with p-phenylenediamine dihydrochloride (PPDD) and Fe (III), and the violet color produced is measured at 597 nm (method B). Linear calibration graphs are obtained in the range 0.5-400 and 0.5-450 microg ml(-1) for I and II, respectively. The limits of detection are 0.4 and 0.2 microg ml(-1) for I and II, respectively. The total flow-rate is 3 ml min(-1) for both drugs. The methods have been successfully applied to the analysis of some pharmaceutical formulations, particularly of the injection and capsule types. The relative standard deviation (RSD) (n = 10) at the 50 and 100 microg ml(-1) levels of I and II were 0.83-0.77 and 0.9-0.8% with N,N-DPPD and PPDD as reagents, respectively. Recoveries were quantitative; the results obtained agreed with those obtained by other reported methods.
[structure: see text] The cephalosporin antibiotic Cefadroxil can be epimerized at the alpha-carbon of its amino acid side chain using pyridoxal as the mediator. By clathration with 2,7-dihydroxynaphthalene, the desired diastereomer can be selectively withdrawn from the equilibrating mixture of epimers. In this way, an asymmetric transformation of Cefadroxil can be accomplished. This opens the possibility of the production of Cefadroxil starting from racemic p-hydroxyphenylglycine, in contrast to the current industrial synthesis that employs the D-amino acid in enantiopure form.