Impurity and assay method combined: One hundred percent level standard is used http://www.selleckchem.com/products/Tipifarnib(R115777).html for quantification; reporting level of impurity to 120% of assay specification. The linearity solutions are prepared by performing serial dilutions of a single stock solution; alternatively, each linearity solution may be separately weighed. The resulting active response for each linearity solution is plotted against the corresponding theoretical concentration. The linearity plot should be visually evaluated for any indications of a nonlinear relationship between concentration and response. A statistical analysis of the regression line should also be performed, evaluating the resulting correlation coefficient, Y intercept, slope of the regression line, and residual sum of squares.

A plot of the residual values versus theoretical concentrations may also be beneficial for evaluating the relationship between concentration and response. In cases where individual impurities are available, it is a good practice to establish both relative response factors and relative retention times for each impurity, compared to the active compound. Response factors allow the end user to utilize standard material of the active constituent for quantitation of individual impurities, correcting for response differences. This approach saves the end user the cost of maintaining supplies of all impurities and simplifies data processing. To determine the relative response factors, linearity curves for each impurity and the active compound should be performed from the established limit of quantitation to approximately 200% of the impurity specification.

The relative response factor can be determined based upon the linearity curve generated for each impurity and the active: There is a general agreement that at least the following validation parameters should be evaluated for quantitative procedures: selectivity, calibration model, stability, accuracy (bias, precision) and limit of quantification.[5] Additional parameters which might have to be evaluated include limit of detection (LOD), recovery, reproducibility and ruggedness (robustness). Selectivity (Specificity) For every phase of product development, the analytical method must demonstrate specificity. The method must have the ability to unambiguously assess the analyte of interest while in the presence of all expected components, which may consist of degradants, excipients/sample matrix, and sample blank peaks.

The sample blank peaks may be attributed to things such as reagents or filters used during the sample preparation. For identification tests, discrimination of the method Drug_discovery should be demonstrated by obtaining positive results for samples containing the analyte and negative results for samples not containing the analyte. The method must be able to differentiate between the analyte of interest and compounds with a similar chemical structure that may be present.