The linearity of an analytical method enables (over the range of dissolution concentration) generation of test results which are directly proportional to the concentration of drug substance in the dissolution sample.

The linearity working standard solutions must contain the biorelevant medium and diluent (optionally) to keep the matrix similar to dissolution samples being analysed.

During the dissolution analysis, obtain the range of linearity (working standard) solutions which must be equivalent to highest release (120%) of the drug product in the biorelevant dissolution and the lowest release (5%) of the drug product in the biorelevant dissolution. Prepare six linearity (working standard) solutions (e.g. 120, 80, 60, 40, 20, 5%). Calculate the slope and correlation coefficient value. Correlation coefficient value must be lie within your in-house limit.

The diagram below explains how to prepare linearity working standard solutions.

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