4.5.3. Precision

Precision reflects how closely measurements of the same homogeneous sample taken under specified conditions agree across numerous measurements obtained from multiple samplings. The six replicate prepared samples from the same formulation batch were injected into HPLC, and the RSD% of 6 sample analyte assays was calculated. The analyte assay RSD% was agreeable, and the current method is precise. The chromatogram is shown in Figure ​Figure33.

Precision chromatogram: 6 individual sample preparations from a homogeneous sample expressing the closeness of agreement between series of measurements.

Variations within laboratories can be expressed by intermediate precision: different days, different analysts, or different equipment. Six test samples were prepared and injected into diverse HPLC columns on different days. In analytical procedures, precision is usually measured as variance, standard deviation, or the coefficient of variation. The RSD% of 6 samples of analyte assay was calculated and the results found to be within the limit.

The F value and F critical value for both the method precision and intermediate precision and the USP monograph method and current method (Method Precision data) were calculated, and we observed that the F value < F critical value. Similarly, the T value and T critical value for both the method precision and intermediate precision and the USP monograph method and current method (Method Precision data) were calculated, and we observed that the T value < F critical value (one tail and two tail). The statistical data reject the null hypothesis and indicate that the two different sets of data and the two different methods of data are not statistically significant. Table 4 and Table 5 show the T and F test data.