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

Importance of the Topic

Hemp, a variety of Cannabis sativa with low tetrahydrocannabinol (THC) content, is widely used for nutritional, pharmaceutical, and cosmetic products due to its high cannabidiol (CBD) and cannabigerol (CBG) levels.

However, hemp crops can accumulate pesticides, fungicides, and mycotoxins, posing health risks and necessitating trace-level (ppb) analysis to ensure consumer safety and regulatory compliance.

Objectives and Study Overview

This work presents a streamlined workflow for the detection and quantification of a broad spectrum of contaminants in hemp.
It integrates hydrophilic-lipophilic-balanced (HLB) solid-phase extraction for sample cleanup with liquid chromatography–tandem mass spectrometry (LC-MS/MS) and gas chromatography–tandem mass spectrometry (GC-MS/MS) for sensitive and reliable analysis.

Methodology and Instrumentation

Sample preparation involved:

• Homogenizing 1 g of dried hemp and spiking with isotopically labeled internal standards.
• Extracting with 1% acetic acid in acetonitrile, followed by cleanup on 200 mg HLB cartridges and concentration under vacuum or positive pressure.
• Rinsing cartridges with methanol to maximize elution of target analytes.
• Secondary cleanup for GC-MS/MS using dispersive SPE (magnesium sulfate and C18), then dilution in hexane/acetone (1% acetic acid).
• Dilution of cleaned extract for LC-MS/MS in methanol:acetonitrile:water (2:2:1) and injection volumes of 1.5 µL (LC) and 1 µL (GC).

Used Instrumentation

• Shimadzu LCMS-8045 coupled to a Raptor ARC-18 column (2.7 µm, 150×2.1 mm)
• Thermo Trace 1310 GC linked to TSQ 8000 MS with Rxi-5ms column (30 m×0.25 mm×0.25 µm)
• HLB SPE cartridges (200 mg) and dSPE tubes with magnesium sulfate and C18 sorbent

Results and Discussion

The method achieved limits of quantification well below regulatory action levels (often <0.1 µg/g), with most calibration curves showing R² >0.99.
Accuracy ranged from 70% to 130%, and precision (RSD) was typically below 30% across spiking levels of 0.01–1.5 µg/g.
HLB cleanup effectively removed hydrophobic interferences, and dSPE minimized residual moisture.
Chromatograms demonstrated clear separation of over 70 pesticides and mycotoxins, confirming the robustness of both LC-MS/MS and GC-MS/MS approaches.

Benefits and Practical Applications

• Comprehensive screening for regulatory contaminants in hemp products.
• Robust sample cleanup reduces matrix effects, enhancing analytical reliability.
• High-throughput workflow suitable for quality control and compliance laboratories.
• Alignment with state and international regulatory limits for hemp and inhalable cannabis.

Future Trends and Opportunities

• Adoption of high-resolution mass spectrometry to expand analyte coverage and improve specificity.
• Automation of SPE and dilution steps to increase laboratory throughput and reproducibility.
• Integration of data analytics and artificial intelligence for advanced screening and risk assessment.
• Development of portable mass spectrometry platforms for in-field or on-site testing.

Conclusion

The validated LC-MS/MS and GC-MS/MS workflow delivers sensitive, accurate, and precise determination of pesticides and mycotoxins in hemp.
By meeting regulatory requirements and achieving robust performance metrics, this approach supports safe production and quality assurance of hemp-derived products.