Pao Chi Liao

  • Designation: National Cheng Kung University
  • Country: Taiwan
  • Title: Targeted and Suspect Screening of New Psychoactive Substances (NPS), Illicit Drugs, and Related Compounds in Taiwanese Wastewater using High-Resolution Mass Spectrometry


Dr. Pao-Chi Liao completed his Ph.D. in Analytical Chemistry from Michigan State University (MSU) in 1995 before doing postdoctoral research in the Department of Biochemistry at MSU. Dr. Liao joined the faculty at the Department of Environmental and Occupational Health, National Cheng-Kung University, Taiwan, in 1997, where he was promoted to full professor in 2006 and named Distinguished Professor in 2011. Dr. Liao’s research interests and specialty fields include analytical chemistry, mass spectrometry, metabolomics/proteomics, biomarker discovery, cancer biomarkers, lung cancer metastasis, and environmental and occupational health.


Over the past few years, the emergence of new psychoactive substances (NPSs) has become a significant public health issue for society. Traditionally, police seizures, population surveys, and urine testing are usually employed to monitor the trends of the use and abuse of drugs. To obtain sufficient consumption data on drug abuse, wastewater-based epidemiology is proven as an alternative tool for monitoring the use of abused drugs objectively. This study aims to analyze the prevalence of NPSs and other illicit drugs in wastewater collected from a Taiwanese wastewater treatment plant using high-resolution mass spectrometry (HRMS) based targeted and suspect screening procedures. Using the suspect list generated from the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) library, containing approximately 3600 drugs and drug-related compounds, the proposed strategy successfully identified one hundred compounds by targeted (N=8) and suspect screening (N=92), respectively. Among ninety-two compounds identified by the suspect screening approach, fifteen are regulated by both the government in the ROC (Taiwan) and the U.S., with opiate analgesics being the most dominant class. Methylenedioxypyrovalerone (MDPV) and 4-methyl-N, N-dimethylcathinone, consistent with seizure reports of NPSs in Taiwan, were identified in the wastewater samples. This correlation emphasizes the reliability of identifying NPSs in wastewater to monitor their misuse. Moreover, the existence of 5-methoxy-2-aminoindane, previously undocumented in the Taiwanese regulation, suggests the recent appearance of this potential NPS by drug dealers to circumvent regulations. This study highlights the potential value of employing comprehensive HRMS-based targeted and suspect screening methodologies in wastewater analysis for researching and controlling the use of illicit drugs.

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