Amid a wave of synthetic drugs in recent years, Kensington, Pennsylvania has emerged as the locus for a different kind of experimentation, through a new generation of freelance entrepreneurs. Their bathtub chemistry is often guided by trial and error—leaving doctors, public health officials and harm reductionists struggling to understand the latest side effects.

Last year, a concerned toxicologist from the nonprofit Center for Forensic Science Research & Education (CFSRE) at the Fredric Rieders Family Foundation, the academic and research arm of NMS Labs outside Philadelphia, conceived of a new testing program. It employs sophisticated mass spectrometry to reveal the composition of retail-level street drugs.

Alex Krotulski, an associate director of the CFSRE, spoke to Narcotica co-host Chris Moraff about everything from synthetic cannabinoids like 5F-APB to carfentanil to xylazine.