CHARACTERISATION OF DELTA-8 -THC DISTILLATES USING HPLC WITH PDA AND MASS SPECTROMETRY DETECTION

Significance of the Topic

Delta-8-THC has emerged as a rapid-growth cannabinoid in consumer products derived from hemp, raising safety and regulatory concerns due to its intoxicating effects and the potential presence of synthesis byproducts. Accurate characterization of Δ8-THC distillates is essential for ensuring product purity, consumer safety, and compliance with evolving regulations.

Objectives and Study Overview

This study aims to develop and demonstrate a robust analytical workflow for the identification and quantification of Δ8-THC and related cannabinoids in distillate samples. Key goals include:

• Separating neutral cannabinoid isomers using HPLC.
• Detecting compounds via photodiode array (PDA) and single-quadrupole mass spectrometry.
• Utilizing software tools for spectral library matching and in-source fragmentation analysis.

Instrumentation Used

The following instrumentation and software were employed:

• ACQUITY Arc HPLC system with CORTECS C18 column (4.6×100 mm, 2.7 µm).
• 2998 PDA detector (210–400 nm, single wavelength at 228 nm).
• ACQUITY QDa single-quadrupole mass detector (ESI+, 100–800 Da, cone voltages 15 V and 45 V).
• Empower chromatography data software with a custom cannabinoid spectral library.

Methodology

Samples and standards were dissolved in acetonitrile and injected (5 µL) onto the HPLC column. A binary gradient of 0.1% formic acid in water (solvent A) and acetonitrile (solvent B) delivered separation at 25 °C and 1.592 mL/min. PDA detected UV absorbance at 228 nm, while MS acquired [M+H]+ data. Unknown peaks were explored through retention time alignment, PDA spectral comparison, mass spectral matching against the in-house library, and in-source fragmentation experiments at varying cone voltages.

Key Results and Discussion

The neutral cannabinoid mixture baseline-separated ten compounds, including CBD, CBN, exo-THC, Δ9-THC, and Δ8-THC. Analysis of a Δ8-THC distillate revealed:

• A dominant Δ8-THC peak (66 % area) at tR 5.35 min.
• Multiple minor peaks (2–12 % area) with identical [M+H]+ m/z 315, indicating possible isomeric cannabinoids eluting between 4.0 and 7.0 min.
• Successful library matching for two late-eluting unknowns at tR 6.15 min and 6.53 min.
• In-source fragmentation confirming the identity of (6aR,9R)-Δ10-THC through characteristic product ions (m/z 259, 193, 135, 123).

Benefits and Practical Applications

Implementing HPLC-PDA-MS with software-driven spectral library searching offers:

• Reliable differentiation of cannabinoid isomers in complex matrices.
• Rapid screening of Δ8-THC products for safety and regulatory compliance.
• Enhanced confidence in component identification via combined UV and mass fragmentation data.

Future Trends and Possibilities

Advancements may include high-resolution MS for deeper structural elucidation, expanding spectral libraries to cover novel cannabinoids and byproducts, and integrating automated workflows for high-throughput quality control. Coupling ion mobility or tandem MS could further resolve co-eluting isomers and reduce false positives.

Conclusion

The presented HPLC-PDA-MS approach effectively separates and identifies Δ8-THC and related cannabinoid isomers in distillates. Library matching and in-source fragmentation increased identification confidence for unknown peaks. Such workflows are critical for ensuring product safety in the rapidly evolving cannabinoid market.

References

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