Multitechnique Approach for Xylazine Detection: Chemical Spot Tests, Immunoassays, and Scanning Electron Microscopy

Area of Science:

• Forensic Chemistry
• Toxicology
• Public Health

Background:

• Xylazine is increasingly found in illicit drug supplies, often mixed with fentanyl.
• Its presence raises safety concerns due to severe toxicity and lack of specific antidotes.
• Current presumptive testing methods for xylazine are underdeveloped for forensic and public health applications.

Purpose of the Study:

• To evaluate the effectiveness of various presumptive screening methods for xylazine detection.
• To identify reliable field-deployable tests for xylazine in forensic and public health settings.

Main Methods:

• Evaluation of chemical spot tests using reagents like cobalt thiocyanate, Eosin Y, and others.
• Assessment of microcrystalline tests with reagents such as gold chloride, analyzed via light microscopy and SEM.
• Testing of commercially available xylazine immunoassay test strips and other drug screening kits.

Main Results:

• Several chemical spot tests (cobalt thiocyanate, Eosin Y, Liebermann, Mandelin, Mecke, Marquis, Scott, Young) showed distinct color changes with xylazine.
• Gold chloride reagent produced reproducible microcrystals for xylazine identification under microscopy.
• Xylazine test strips provided positive results, but other commercial kits exhibited cross-reactivity or false positives, questioning their specificity.

Conclusions:

• Reliable presumptive screening tests for xylazine are needed to support forensic investigations and harm reduction.
• Validated, xylazine-specific tests are crucial for accurate detection in illicit drug samples.
• Improved testing facilitates informed decision-making for people who use drugs (PWUDs) and public health initiatives.