Illicit and abused drugs in sewage sludge: method optimization and occurrence

Area of Science:

• Environmental Chemistry
• Forensic Science
• Analytical Chemistry

Background:

• Sewage sludge analysis offers insights into community drug consumption patterns.
• Limited methods exist for comprehensive drug and metabolite detection in complex matrices like sewage sludge.

Purpose of the Study:

• To develop and validate a sensitive and reliable method for determining 20 abused and illicit drugs and their metabolites in sewage sludge.
• To investigate the presence and levels of specific drugs, including novel cannabinoids, in sewage sludge for the first time.

Main Methods:

• Pressurized liquid extraction (PLE) of freeze-dried sewage sludge samples.
• Solid-phase extraction (SPE) for extract clean-up.
• Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) for analyte determination.
• Use of isotopically labeled analogs as surrogate standards to correct for matrix effects and extraction losses.

Main Results:

• Quantification limits below 3.3 ng/g dry weight (d.w.) for most compounds, and 8.2–22.5 ng/g d.w. for cannabinoids.
• Method repeatability below 14% for most compounds.
• Cannabinoids (Δ(9)-tetrahydrocannabinol [THC], cannabinol [CBN], cannabidiol [CBD]), methadone, and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) were the most frequently detected and abundant compounds.
• Maximum concentrations exceeded 100 ng/g d.w. for these compounds, with THC reaching up to 579 ng/g d.w.
• First-time evidence of CBN, CBD, and THC presence in sewage sludge.

Conclusions:

• The developed LC-MS/MS method is sensitive, reliable, and suitable for routine monitoring of abused drugs in sewage sludge.
• The study provides the first evidence of specific cannabinoids in sewage sludge, expanding the scope of drug monitoring in environmental samples.
• Findings highlight the prevalence of cannabinoids and methadone/EDDP in the studied sewage sludge, offering valuable data for public health and forensic investigations.