Table 1 System suitability parameters Range and linearity The range of an analytical method is the interval between the upper and lower analytical concentration of a sample where the method has shown to demonstrate acceptable accuracy, precision, and linearity. The linearity of an analytical method is its ability to elicit test results that are directly selleck kinase inhibitor proportional to the concentration of an analyte in the sample within a given range. The linearity of the method was observed in the expected concentrated range, demonstrating its suitability for analysis [Table 2]. The linearity curve of doxofylline and montelukast sodium was shown in Figures Figures44 and and55. Table 2 Linearity data details for montelukast sodium and doxofylline Figure 4 Doxofylline linearity curve.

Y = Mx + C = regression equation, R2 = correlation co-efficient Figure 5 Montelukast sodium linearity curve. Y = Mx + C = regression eqution, R2 = correlation co-efficient Accuracy Accuracy of an analytical method is the closeness in agreement between the accepted true value or a reference value and the actual result obtained. Accuracy studies are usually evaluated by determining the recovery of a spiked sample of the analyte into the matrix of the sample to be analyzed. The results of accuracy studies are shown in Table 3. Recoveries of doxofylline and montelukast sodium were laid between 98% and 102%. This is evident that the method is accurate within the desired range. Table 3 Accuracy/recovery data for montelukast sodium and doxofylline��spiking method WS is working standard of drug, % RSD is percentage relative standard deviation, n = 3 is three observation.

Precision Precision is a measure of the ability of the method to generate reproducible results. The precision of a method is evaluated using three separate determinations for repeatability, intermediate precision, and reproducibility. The results of intra- and interday variations are shown in Table 4. The results obtained from intermediate precision also indicated a good method precision. All the data were within the acceptance criteria. Table 4 Intra- and inter-day precision study Ruggedness The ruggedness of an analytical method is the degree of reproducibility of the test results obtained by the samples under a variety of conditions, such as different laboratories, different analysts, different instruments, different lots of reagents, and different days. The %RSD of below 2% indicated that the method was accurate with high precision [Table 5]. Table 5 Ruggedness data for tablet analysis Robustness Robustness is a measure of the performance of a method when small deliberate changes are Brefeldin_A made to the conditions of the method. The results of the robustness study are summarized in Table 6.