e. tablet) Validation It was validated as per the http://www.selleckchem.com/products/CAL-101.html ICH guide lines.[16�C18] Linearity It was found that the selected drug shows linearity in the range 10�C80 ��g/mL. Accuracy It was found out by a recovery study using the standard addition method. Known amounts of standard gemifloxacin were added to pre-analyzed samples at a level from 80% up to 120% and then subjected to the proposed spectrophotometric method. The results of recovery studies are shown in Table 5. Table 5 Recovery data of gemifloxacin Precision Intra-day precision of the assay samples containing gemifloxacin (30 ��g/mL) was analyzed at every half an hour interval of time in a day. Precision was calculated as an intra-day coefficient of variation [% CV=(SD/mean) �� 100] or % RSD as shown in the Table 6. The color complex was stable for 6 h.
Table 6 Intra-day precision data of gemifloxacin Sensitivity The sensitivity of the method was determined with respect to LOD and LOQ. The LOD and LOQ were separately determined based on the standard calibration curve. LOD=(3.3 �� SD/S), LOQ=(10 �� SD/S), where SD is the standard deviation of the y-intercept of regression line and S is the average slope of the calibration curve. The lower limit of detection and the limit of quantitation were found to be 0.2563 ��g/mL and 0.7767 ��g/mL, respectively. RESULTS AND DISCUSSION In aqueous acidic medium, gemifloxacin reacts with methyl orange, forms a yellow-colored complex, which is extracted in chloroform and analyzed. The method was optimized with the following parameters: Buffer strength: Various pH strengths of acetate buffer, i.
e., 2.8, 3, 3.4, 3.7, and 4, were tried for the selection of buffer strength. The optimum buffer strength was found to be 4.0. Reaction time: The optimization of reaction time was done by measuring the absorbance at an interval of 5min up to 60min. A minimum of 5min time was found to be sufficient to complete the reaction. Stability of complex: Stability of the complex was observed, and it remained stable for 6 (six) h. Molar ratio of drug:dye: The molar ratio of drug:dye was determined by Job’s method and found to be 1:2. The analytical wavelength for measuring absorption maximum for the gemifloxacin�Cmethyl orange yellow complex was observed at 427 nm against the reagent blank. Absorption maximum at 412 nm observed for the reagent blank under identical experimental conditions was used.
The extent of formation of complex is governed by the methyl orange concentration. The solute absorbances were plotted as a function Entinostat of yellow concentration. The absorbance of the complexes initially increased in the concentration range of (0.02�C0.25%) methyl orange and then attained practically a constant value in the concentration range of (0.25�C0.28%) methyl orange. Thus, it was found that 0.25% concentration of methyl orange in the range of 3.0�C5 mL and acetate buffer were necessary for the achievement of maximum color intensity. Hence 4.