Fig. 3

Cross-reactivity of BTNX NTS for 33 screened nitazene analogues at 3000 ng/mL and at 1000 and/or 9000 ng/mL. A negative result (‘-’), positive result (‘+’), or indeterminate result (‘?’) is represented by a red, green, or orange rectangle, respectively. The asterisks denote that for N-pyrrolidino 4’-hydroxy nitazene (9) and for N-piperidinyl etonitazene (16) the results from two independent testings are shown, as the first experiment yielded a discrepant result: ImageJ indicated a negative result at 3000 ng/mL and a positive result at 1000 ng/mL. For both substances, the retesting did not yield this discrepancy