High Throughput Determination of Emerging Synthetic Amphetamine Drugs in Untreated Wastewater Using SPE-LC-MS/MS

Importance of the Topic

Environmental monitoring of illicit and emerging psychoactive substances in untreated wastewater offers a noninvasive, real-time approach to assess community drug consumption. High throughput methods capable of detecting low concentrations of diverse synthetic amphetamine analogs enhance public health surveillance, support regulatory compliance, and guide early warning initiatives.

Objectives and Study Overview

This application note describes the development and validation of a rapid, multi-residue LC-ESI-MS/MS method for quantifying 18 synthetic amphetamine new psychoactive substances (NPS) in untreated municipal wastewater. The study aims to achieve low limits of quantification (0.033–300 µg/L), robust performance, and high daily sample throughput to facilitate epidemiological and environmental investigations.

Methodology and Instrumentation

Sample preparation and analysis were streamlined to maximize efficiency:

• Solid-phase extraction (SPE) using an automated Oasis™ MCX LP 96-well plate workflow for cleanup and concentration of 5 mL wastewater aliquots.
• Chromatographic separation on an ACQUITY Premier BEH C18 column (1.7 µm, 2.1 × 100 mm) at 55 °C with a 12-minute gradient using aqueous ammonium acetate/acetic acid and a methanol/acetonitrile mobile phase.
• Detection by Xevo™ TQ-XS tandem quadrupole mass spectrometer in positive electrospray ionization mode, enabling sensitive quantification of methoxetamines, synthetic cathinones, substituted phenethylamines, and other designer amines.

Instrumentation Used:

• ACQUITY UPLC I-Class Plus System
• Xevo TQ-XS Triple Quadrupole Mass Spectrometer
• MassLynx™ 4.2 and TargetLynx™ 4.2 software

Main Results and Discussion

The method delivered excellent chromatographic resolution and retention time reproducibility (%RSD < 0.21). Calibration curves across eight concentration levels exhibited linearity (R2 > 0.99) with back-calculated deviations < 15%. Single-laboratory validation demonstrated mean recoveries between 93.3 and 111.7% and intermediate precision (RSDip) ≤ 11.8% at three QC levels. Limits of quantification as low as 0.033 µg/L were achieved, confirming suitability for trace-level analysis in complex wastewater matrices.

Benefits and Practical Applications

This high throughput SPE-LC-MS/MS workflow offers:

• Reduced sample volume (5 mL) and simplified automated preparation for rapid processing.
• Capacity to analyze over 100 samples per day for timely community exposure assessments.
• Compliance with ISO 17025 and EPA guidelines for reliable environmental and forensic monitoring.

Applications include epidemiological studies of drug use trends, evaluation of mitigation measures, and support for early warning systems.

Future Trends and Opportunities

Advances may include the integration of high-resolution mass spectrometry for suspect screening of novel NPS, development of automated data processing pipelines, and expansion to additional drug classes. Combining wastewater data with geospatial and temporal modeling can further refine public health interventions and policy responses.

Conclusion

The presented SPE-LC-MS/MS method achieves rapid, sensitive, and high throughput quantification of 18 synthetic amphetamine analogs in untreated wastewater. Its robust validation, low limits of quantification, and automated workflow mark a significant enhancement for environmental and public health surveillance of emerging psychoactive substances.

Reference

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