After observing the overlain first-order derivative spectra with scaling factor = 4 and ���� = 4 for NBM and PRCM [Figure 3], zero crossing points of drugs were www.selleckchem.com/products/XL184.html selected for the analysis of other drugs. The first wavelength selected was 261 nm (zero crossing of NBM), where PRCM showed considerable absorbance. The second wavelength selected was 248.2 nm (zero crossing of PRCM), where NBM showed considerable absorbance. Figure 2 Overlain zero-order absorption spectra of 12 ��g/ml nabumetone and 12 ��g/ml paracetamol in methanol Figure 3 Overlain first-order derivative spectra of 12 ��g/ml nabumetone and 12 ��g/ml paracetamol in methanol Calibration curves For each drug, linearity was observed by diluting appropriate aliquots of the working standard stock solution 0.15, 0.3, 0.45, 0.6, 0.

75, and 0.9 ml into a series of 10-ml volumetric flasks with methanol to get a final concentration range of 3�C18 ��g/ml separately for both NBM and PRCM. The samples were scanned in the wavelength range 200400 nm, and the first-order derivative of the spectrum was taken. The dA/d�� of each of these solutions was measured at the selected wavelength and plotted against concentration to obtain the calibration graph. The statistical parameters of the calibration curve, such as correlation coefficient, regression equation, limit of detection, and limit of quantitation, for NBM and PRCM are given in Table 1. Table 1 Optical characteristics of the proposed method (first-order derivative method) Analysis of tablet formulation Twenty tablets were weighed accurately and powdered.

A powder equivalent of 12 mg of NBM (containing 12 mg of PRCM) was weighed and transferred to a 100-ml volumetric flask. Then it was dissolved in 25 ml of methanol by shaking the flask for 15 min, and the volume was made up to the mark with methanol. The solution was filtered through Whatman filter paper no. 41. A 1.0 ml aliquot of the sample stock solution was transferred to a 10-ml standard volumetric flask, and the volume was made up to the mark with methanol. The sample solution of the final concentration of 12 ��g/ml of NBM (containing 12 ��g/ml of PRCM) was analyzed by the first-order derivative spectroscopic method, and absorbance was measured at 261 and 248.2 nm. The procedure was repeated six times for sample analysis. The concentrations of NBM and PRCM were calculated from the calibration graph.

The results of analysis are given in Table 2. Table 2 Results of commercial formulation analysis (n = 3) METHOD VALIDATION Accuracy Batimastat The accuracy of the proposed method was determined by performing recovery study at 80, 100, and 120% level for NBM and PRCM. The recovery study was done by adding pure drug solution to the preanalyzed tablet formulation, and concentrations of NBM and PRCM were determined by using the calibration graph. The values of percent relative standard deviation and recovery studies were showing satisfactory accuracy.