2.6. Accuracy
In each of the three chosen days, 0.5 mL sample of insulin is correspondingly diluted to 50 mL with 0.01M hydrochloric acid and the solution is spiked with 0.5, 1.0 and 2.0 mL of 10 lg Zn/mL reference stock solutions. The spiked sample solutions are analyzed according to the analytical procedure and the recovery is calculated with the following equation: