Analysis of contaminants in hemp using LC-MS/MS and GC-MS/MS

Significance of the Topic

The analysis of pesticide and mycotoxin contaminants in hemp is crucial due to regulatory requirements and public health concerns. Hemp products, rich in CBD and CBG, can accumulate harmful residues during cultivation and processing. Robust, sensitive and reliable analytical methods are needed to ensure consumer safety and compliance with stringent action levels in different jurisdictions.

Objectives and Study Overview

This study presents a comprehensive workflow for the simultaneous determination of a broad spectrum of pesticides and mycotoxins in hemp. The aim was to develop and validate a method that meets minimum required performance levels (MRPLs) at the sub-ppb range using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS).

Methodology

Sample preparation involved extraction of 1 g pulverized hemp with acidified acetonitrile, cleanup using hydrophilic-lipophilic balanced (HLB) SPE cartridges, and a secondary cleanup with magnesium sulfate/C18 dispersive SPE for GC analysis. For LC-MS/MS, extracts were diluted in a methanol:acetonitrile:water mixture before injection. GC-MS/MS analysis required transfer of cleaned extracts to a dSPE tube and dilution in hexane:acetone before injection.

Instrumentation Used

• LC-MS/MS: Shimadzu LCMS-8045 with electrospray ionization, using a Raptor ARC-18 column (2.7 µm, 150 × 2.1 mm) and a gradient of methanol and aqueous ammonium formate with formic acid.
• GC-MS/MS: Thermo Trace 1310 gas chromatograph coupled to TSQ 8000 mass spectrometer with electron ionization, using an Rxi-5 ms column (30 m × 0.25 mm × 0.25 µm) and temperature program from 70 °C to 315 °C.

Key Results and Discussion

Validation metrics demonstrated low limits of quantitation (0.02 to 0.5 µg/kg) well below regulatory action levels, high linearity (R²>0.99 for most analytes), and satisfactory recovery and precision (70–130% accuracy, <30% RSD). Chromatographic separation effectively resolved target analytes from matrix interferences, and isotopically labeled internal standards enhanced quantitation reliability.

Benefits and Practical Applications

This workflow enables high-throughput, accurate monitoring of multiple contaminants in hemp, supporting quality control and regulatory compliance in the cannabis industry. The approach can be integrated into routine testing laboratories for product safety assessment and traceability.

Future Trends and Potential Applications

Advancements may include automation of sample preparation, miniaturized and high-resolution mass analyzers for expanded screening, rapid on-site testing, and integration with data analytics for real-time decision-making. The methodology can be further adapted to novel cannabinoids and emerging contaminants.

Conclusion

The proposed LC-MS/MS and GC-MS/MS workflow provides a robust, sensitive and efficient solution for multi-residue contaminant analysis in hemp, meeting international regulatory standards and ensuring the safety of hemp-derived products.