Multi-Element Analysis of Cannabis and Hemp using ICP-MS

Importance of the topic

Cannabis and hemp products have seen rapid legalization and adoption worldwide for therapeutic and recreational use. Ensuring these materials are free from toxic and unwanted inorganic contaminants is critical for consumer safety, regulatory compliance, and accurate nutritional labeling. Trace element profiling also supports quality control throughout cultivation and processing, preventing health risks associated with arsenic, cadmium, lead, mercury, and other metals.

Objectives and overview

This study demonstrates a robust, multi-element analytical workflow for cannabis and hemp matrices using the Agilent 7800 ICP-MS. Key aims include simultaneous quantification of 25 elements across diverse sample types (plant material, tablets, tinctures, edibles, topical products), validation of sample preparation protocols, and evaluation of instrument performance in high-matrix contexts.

Methodology and instrumentation

• Sample preparation: Microwave-assisted acid digestion with 4 mL HNO₃ and 1 mL HCl per ~0.15–0.5 g of sample to ensure complete breakdown of organic matter and stabilization of Ag/Hg.
• Instrument: Agilent 7800 ICP-MS equipped with High Matrix Introduction (HMI) for in-line dilution (4×), helium collision mode for polyatomic interference removal, and automated half-mass correction for doubly charged rare earths affecting As and Se.
• Sample introduction: SPS 4 autosampler, Micromist glass concentric nebulizer, quartz spray chamber, and quartz torch with 2.5 mm injector; nickel-plated copper cones.
• Calibration: Multi-level standards (1% HNO₃/0.5% HCl matrix) covering major elements in ppm, trace elements and Hg in ppb; verification using NIST SRMs (Peach Leaves 1547, Tomato Leaves 1573a, Pine Needles 1575, Natural Water 1640a).
• Quality control: Initial and continuing calibration verifications (ICV/CCV), internal standard monitoring (Li, Sc, In, Lu, Ge, Bi), and spike recovery tests across sample types.

Main results and discussion

• Calibration performance: Excellent linearity for critical toxic elements (As, Cd, Pb, Hg) with detection limits in the low ppb range and background equivalent concentrations below 1 ppb for many analytes.
• SRM recoveries: Most elements recovered within 93–104% of certified values; half-mass correction improved As and Se accuracy, mitigating interferences from REE double-charged ions.
• Internal standard stability: ISTD signals remained within ±20% over ~4 hours and 58 samples, confirming robust plasma conditions with HMI.
• Sample analysis: Cannabis samples exhibited variable levels of As (up to 160 ppb), Cd (up to 11 ppb), Pb (up to 55 ppb), Co, Ni, Cr, and other elements; tinctures and tablets showed lower concentrations but still required monitoring.
• Spike recoveries: All elements in spiked samples returned within ±20% of expected values, demonstrating method accuracy in real-world matrices.

Benefits and practical applications

• High sensitivity and wide dynamic range enable simultaneous detection of major and trace elements.
• HMI-based automated dilution reduces manual sample handling, contamination risk, and operator time.
• He collision mode and half-mass correction ensure reliable removal of polyatomic and doubly charged interferences.
• Quick Scan data acquisition offers semiquantitative screening across the full mass range for non-target elements.
• Applicable for routine quality control, regulatory compliance testing, and safety screening at all stages of cannabis and hemp production.

Future trends and potential uses

• Integration of speciation techniques to distinguish elemental forms (e.g., inorganic vs. organic mercury).
• Miniaturization and field-deployable versions of ICP-MS for on-site screening in cultivation and processing facilities.
• Advanced automation and software analytics for real-time process monitoring and data-driven quality assurance.
• Expansion of validated methods to emerging contaminants such as metal-based nanoparticles and isotopic profiling for provenance verification.
• Harmonization of global regulatory standards and validated protocols for consistent interlaboratory results.

Conclusion

The Agilent 7800 ICP-MS with HMI and helium collision mode provides a streamlined, accurate, and sensitive solution for multi-element analysis of cannabis, hemp, and derivative products. Automated dilution, robust interference correction, and comprehensive QC ensure reliable detection of toxic and nutritional elements, supporting safety, compliance, and product quality in a rapidly evolving industry.

References

• National Conference of State Legislatures. State Medical Marijuana Laws. NCSL; October 2017.
• Filipiak-Szok A, et al. Journal of Trace Elements in Medicine and Biology. 2015;30:54–58.
• Gray PJ, Mindak WR, Cheng J. Elemental Analysis Manual for Food and Related Products, FDA, 2015.