Fig. 3.

Accuracy of enalapril/enalaprilat samples, obtained with pre-spiked blood collection tubes, in relation to reference values. The dark grey area indicates the acceptable accuracy of the bioanalytical method according to EMA/FDA Guidelines (±15%). The light grey area indicates the extended tolerance range based on additional influencing factors of the artificial setting of the feasibility study (58%–153%). * denotes results from the re-run for the site that did not pass the feasibility study in its first attempt.