Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

A Multi-Laboratory Investigation of Drug Background Levels



Edward R. Sisco, Marcela N. Najarro


Identifying, quantifying, and analyzing the drug background in operational environments such as forensic laboratories is an emerging body of research. Understanding these levels can provide critical information to address 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 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.
Forensic Chemistry


Narcotics, Background, Quantitation, LC-MS/MS, TD-DART-MS


Sisco, E. and Najarro, M. (2019), A Multi-Laboratory Investigation of Drug Background Levels, Forensic Chemistry, [online], (Accessed July 19, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created September 9, 2019, Updated September 26, 2019