Fig. 2
From: Testing the test strips: laboratory performance of fentanyl test strips
Fentanyl test strip reactivity with interferences. BTNX Rapid Response Fentanyl Test Strip (20Â ng/mL cutoff) limits of cross-reactivity for interferences. POS indicates a positive result, NEG indicates a negative result, N/A indicates a lack of control line on multiple tests indicating an invalid test, and Not Tested indicates concentrations not evaluated