Mohamed Abd El-Maaboud I, Abdelmageed Osama H, Refaat Ibrahim H
Assiut University, Faculty of Pharmacy, Department of Pharmaceutical Analytical Chemistry, Assiut, Egypt.
J AOAC Int. 2007 Jan-Feb;90(1):128-41.
Simple chemometrics-assisted spectrophotometric methods are described for determination of 2 antibacterial binary mixtures. The mixtures are composed of norfloxacin in combination with tinidazole and erythromycin (as ethylsuccinate ester or stearate salt) in combination with trimethoprim. The normal UV absorption spectra of each pair of drugs in the studied mixtures, in the range of 200-400 nm, showed a considerable degree of spectral overlapping: 77.5% for the norfloxacin-tinidazole mixture and 84.3% for the erythromycin-trimethoprim mixture. Resolution of the norfloxacin-tinidazole mixture and trimethoprim in the presence of erythromycin was accomplished successfully by using zero-crossing first derivative (1D), classical least-squares (CLS) regression analysis, and principal component regression (PCR) analysis methods. In addition, an alternative simple and accurate colorimetric method was developed for the determination of erythromycin in the presence of trimethoprim using 2,4-dinitrophenylhydrazine. All variables affecting the development of the colored chromogen were studied and optimized, and the product was measured at 526-529 and 538-542 nm for erythromycin stearate and erythromycin ethylsuccinate, respectively. For zero-crossing, first derivative technique Beer's law was obeyed in the general concentration range of 2-50 microg/mL for norfloxacin, tinidazole, and trimethoprim with good correlation coefficients (0.9994-0.9996). Overall limits of detection (LOD) and quantification (LOQ) ranged from 0.59 to 2.81 and 1.96 to 9.33 microg/mL, respectively. The obtained results from CLS and PCR were compared with those obtained from a 1D spectrophotometric method. With the exception of erythromycin, overall recoveries in the average range of 97.33-103.0% were obtained with a considerable degree of accuracy when the suggested methods were applied to analysis of synthetic binary mixtures, some commercial dosage forms such as tablets and oral suspension without interference from the commonly encountered excipients and additives. For the colorimetric method, Beer's law was obeyed in the general concentration range of 7.21-28.84 microg/mL erythromycin with good correlation coefficients (0.9980-0.9996). Overall LOD and LOQ ranged from 0.73 to 1.65 and 2.43-5.49 microg/mL, respectively. Erythromycin derivatives were determined in the commercial dosage form, without interference from trimethoprim-encountered excipients and additives. The obtained results, with both chemometric and colorimetric methods, have been compared with those obtained from reported methods, and proper F- and t-values were observed, indicating no significant difference between the results of the suggested methods and reported method(s). The good percentage recoveries and proper statistical data obtained proved the efficiency of the proposed procedures for the determination of the studied drugs in their binary mixtures as well as in the commercial dosage forms with quite satisfactory precision.
描述了简单的化学计量学辅助分光光度法用于测定两种抗菌二元混合物。这些混合物由诺氟沙星与替硝唑组合而成，以及红霉素（琥珀酸乙酯或硬脂酸盐）与甲氧苄啶组合而成。在所研究混合物中，每对药物在200 - 400 nm范围内的正常紫外吸收光谱显示出相当程度的光谱重叠：诺氟沙星 - 替硝唑混合物为77.5%，红霉素 - 甲氧苄啶混合物为84.3%。通过使用零交叉一阶导数（1D）、经典最小二乘法（CLS）回归分析和主成分回归（PCR）分析方法，成功实现了在红霉素存在下诺氟沙星 - 替硝唑混合物和甲氧苄啶的分辨。此外，开发了一种替代的简单准确的比色法，用于在甲氧苄啶存在下使用2,4 - 二硝基苯肼测定红霉素。研究并优化了影响有色发色团形成的所有变量，对于硬脂酸红霉素和琥乙红霉素，分别在526 - 529 nm和538 - 542 nm处测量产物。对于零交叉一阶导数技术，在2 - 50 μg/mL的一般浓度范围内，诺氟沙星、替硝唑和甲氧苄啶遵守比尔定律，相关系数良好（0.9994 - 0.9996）。总体检测限（LOD）和定量限（LOQ）分别为0.59至2.81 μg/mL和1.96至9.33 μg/mL。将CLS和PCR获得的结果与1D分光光度法获得的结果进行了比较。除红霉素外，当将建议的方法应用于合成二元混合物、一些商业剂型如片剂和口服混悬液的分析时，总体回收率平均在97.33 - 103.0%范围内，具有相当高的准确度，且不受常见辅料和添加剂的干扰。对于比色法，在7.21 - 28.84 μg/mL红霉素的一般浓度范围内遵守比尔定律，相关系数良好（0.9980 - 0.9996）。总体LOD和LOQ分别为0.73至1.65 μg/mL和2.43 - 5.49 μg/mL。在商业剂型中测定了红霉素衍生物，不受甲氧苄啶常见辅料和添加剂的干扰。将化学计量学方法和比色法获得的结果与报道方法获得的结果进行了比较，观察到合适的F值和t值，表明建议方法的结果与报道方法的结果之间无显著差异。获得的良好回收率百分比和合适的统计数据证明了所提出的程序用于测定二元混合物以及商业剂型中所研究药物的效率，具有相当令人满意的精密度。
