WCPS: New Standardized Methods for Metals in Cannabis

Significance of the Topic

Cannabis products are increasingly consumed for medical and recreational use. Ensuring they meet safety criteria for toxic metal content is critical to protect public health and comply with regulatory requirements.

Goals and Overview of the Study

This work presents the validation of new ICP-MS methods adopted by AOAC and ASTM for quantifying arsenic, cadmium, mercury and lead in diverse cannabis and hemp matrices. The aim was to establish robust, consensus-driven protocols with official status.

Methodology and Instrumentation

Sample digestion employed microwave-assisted acid treatment using HNO3 and HCl in TFM vessels. Calibration standards were prepared in dilute acid. The following instrumentation was used:

• Agilent 7850 ICP-MS equipped with UHMI system and ORS4 collision/reaction cell
• Agilent SPS 4 autosampler
• Micro Mist glass concentric nebulizer and quartz spray chamber
• Quartz torch with 2.5 mm injector and nickel-plated cones
• MARS 6 microwave digestion system (CEM)

Main Results and Discussion

Calibration for As, Cd, Hg and Pb showed excellent linearity, with LOQs ≤10 ppb. Recovery studies on four NIST SRMs and spiking tests across low, medium and high levels met AOAC SMPR criteria (60–115% for low spikes, 80–115% for medium/high). IntelliQuant screening revealed occasional rare earth element interferences, highlighting the value of semi-quantitative profiling.

Benefits and Practical Applications

The standardized methods enable laboratories to generate reliable, reproducible data across a wide range of cannabis-based products, supporting regulatory compliance and quality control. Integration of UHMI and CRC technologies minimizes matrix and spectral interferences.

Future Trends and Possibilities

Further development may focus on expanding target analytes, high-throughput workflows, automated interference correction and incorporating isotopic or speciation analyses. Collaborative efforts could lead to additional official methods for other contaminants in cannabis.

Conclusion

The adoption of AOAC and ASTM ICP-MS protocols for metal analysis in cannabis provides laboratories with validated, consensus methods, ensuring accurate assessment of As, Cd, Hg and Pb in complex matrices.

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