What’s in the Powder? Evaluating Fentanyl Test Strip Sensitivity to Common Household Items in Chemical Emergency Response Scenarios

The increasing prevalence of opioid misuse, particularly the adulteration of illicit substances with fentanyl, has heightened the need for effective field detection methods for unknown powders. First responders, including chemical emergency response and Hazardous Materials (HazMat) teams, face significant challenges in assessing chemical threats in real-time without the resources of a controlled laboratory environment. Immunoassay test strips are commonly used for drug detection and are considered potential tools for identifying fentanyl in emergency scenarios. However, the impact of common diluents (substances such as sugar, flour, and other commonplace additives) on the accuracy of these test strips is unexplored. This study evaluates the limit of detection (LOD) of a popular commercially available fentanyl test strip (FTS) in the presence of various diluents commonly found in emergency situations. The experimental LOD was determined to be 0.05 μg/mL, significantly lower than the reported LOD of 0.20 μg/mL. While no false positives were observed with diluents alone, the presence of diluents in fentanyl solutions altered FTS results, requiring higher concentrations of fentanyl to achieve a positive reading. Results were often difficult to interpret, particularly near the LOD, which could pose challenges for first responders in real-world scenarios. This work is the first to assess the application of FTS to chemical emergency response situations and threat assessment of unknown powders. Commercially available FTS are cost-effective, user-friendly, provide rapid results, and detect low concentrations of fentanyl even in the presence of other substances.