Beyond Fentanyl Test Strips: Investigating Other Urine Drug Test Strips for Drug Checking Applications

Area of Science:

• Forensic Science
• Analytical Chemistry
• Public Health

Background:

• Drug checking services increasingly use immunoassay test strips for fentanyl and xylazine detection.
• The expansion of drug checking necessitates evaluating the utility of existing urine test strips for direct drug product analysis.

Purpose of the Study:

• To investigate the applicability of seven types of urine immunoassay test strips for drug checking applications.
• To assess the reproducibility, sensitivity, cross-reactivity, and thermal stability of these test strips.

Main Methods:

• Evaluated seven urine immunoassay test strips (amphetamine, benzodiazepine, cocaine, methamphetamine, nitazene, opiate, xylazine) for drug checking.
• Assessed reproducibility, sensitivity (microg/mL levels), cross-reactivity, and impact of elevated temperatures.
• Tested the viability of expired test strips.

Main Results:

• Test strips were generally reproducible and sensitive to trace analyte levels.
• Most tests showed minimal impact from prolonged storage at elevated temperatures.
• Significant cross-reactivity was observed with non-target compounds, and expired strips retained sensitivity.

Conclusions:

• Urine immunoassay test strips can detect target analytes in drug samples but exhibit cross-reactivity.
• Understanding cross-reactivity is crucial for accurate interpretation in drug checking.
• Expired test strips may remain viable, but further validation is recommended.