Fig. 1From: Assessment of two brands of fentanyl test strips with 251 synthetic opioids reveals “blind spots” in detection capabilitiesFentanyl structure with labeled moieties and carbons (A) and fentanyl haptens reported by Barrientos [21, 22] (B), Raleigh [23] (C), and Haile [24] (D)Back to article page