9. Use the profile to decide whether the method is valid

Currently, in the literature and in standards dealing with the accuracy profile, it is proposed to define as the validity range of the method the concentration range for which the limits of the dispersion intervals β- ID lie between the acceptability limits $\pm AL$ . This leads to the following conclusions for the example.

• In the case of nicotinamide in milk, we can see that the upper limit of β-ID intersects the upper limit of acceptability at around 0.4 mg L - ¹ (a finer calculation shows that the intersection is at 0.399 mg L - ¹ ). Overall, below 0.4 mg L - ¹ , the analyst can...