A multi-laboratory investigation of drug background levels.

Identifying and quantifying the drug background in operational environments such as forensic laboratories is an emerging body of research. Knowing these levels is crucial to addressing issues like occupational exposure risk - due to the emergence of potent novel psychoactive substances and synthetic opioids - and data integrity - due to improvements in instrument sensitivity. The work presented here builds upon a prior study to provide a broader representation of the average drug background levels found on surfaces in forensic laboratories. Over 700 samples from 20 laboratories were collected, extracted, and analyzed quantitatively using LC-MS/MS, and qualitatively using TD-DART-MS. Quantitative analysis by LC-MS/MS included a panel of 18 drugs while the non-targeted qualitative analysis by TD-DART-MS screened for over three hundred drugs and excipients. The study focused primarily on surfaces within the drug unit and evidence receiving area of the laboratories, but also investigated other operational units (crime scene, drug interdiction, latent prints, and toxicology) as well as report writing. Background levels were highest within the drug unit of the laboratory, though detectable (tens of nanograms) levels were observed in nearly all sampled areas. The data from this expanded study plays a critical role in addressing laboratory concerns such as establishing drug identification reporting limits for new instrumentation and establishing new workflow or cleaning protocols while also providing a more comprehensive dataset for general environmental background studies.