Fig. 1From: High concentrations of illicit stimulants and cutting agents cause false positives on fentanyl test stripsFTS with fentanyl standard: FTS ran with fentanyl standard at 125 ng/mL (a), 100 ng/mL (b), 83 ng/mL (c), 63 ng/mL (d), 50 ng/mL (e), 25 ng/mL (f), and 5 ng/mL (g). Fentanyl threshold line determined to be at 25 ng/mL correlating to 1152 counts (SD = 72)Back to article page