Pyrrolizidine Alkaloids: Characterization in Botanical and Dietary Supplements using Accurate-Mass Q-TOF LC/MS and All Ions MS/MS

Importance of the Topic

The presence of pyrrolizidine alkaloids (PAs) and their N-oxides (PANOs) in botanical products and dietary supplements poses a significant health risk due to their hepatotoxicity, potential to cause veno-occlusive disease and long-term carcinogenic effects. Regulatory bodies have set strict intake limits, but the structural diversity and limited availability of reference standards hinder comprehensive screening and quantification. A robust analytical approach is essential to ensure consumer safety and product quality.

Objectives and Study Overview

This work aimed to develop a comprehensive workflow for both targeted and untargeted detection, characterization, tentative identification, and quantification of PAs and PANOs in complex botanical and dietary supplement matrices. By leveraging accurate-mass Q-TOF LC/MS with All Ions MS/MS and a custom spectral library, the study sought to overcome the limitations of conventional triple quadrupole methods that require specific standards and cannot screen unknown compounds.

Methodology

• Sample set: 44 botanical and dietary supplement samples covering genera such as Senecio, Eupatorium, Petasites, Symphytum and others.
• Extraction: Sonication of 50 mg dried plant material in methanol (2.5 mL) for five successive cycles, followed by centrifugation, combination of supernatants to 10 mL and filtration prior to analysis.
• Library creation: Analysis of 25 PA/PANO reference standards (1 mg/mL in methanol) in targeted MS/MS mode at multiple collision energies; spectra averaged and compiled into a personal compound database and spectral library (PCDL).

Used Instrumentation

• Liquid chromatography: Agilent 1290 Infinity LC system with Poroshell 120 EC-C18 column (2.1×150 mm, 2.7 µm), gradient elution with 0.1% formic acid in water and acetonitrile, flow rate 0.27 mL/min, column at 40 °C.
• Mass spectrometry: Agilent 6530 Accurate-Mass Q-TOF LC/MS with Jet Stream dual ESI source; full-scan range 50–950 m/z; All Ions MS/MS alternating 0 eV and 30 eV; external reference mass correction at m/z 121.0509 and 922.0098.
• Data processing: Agilent MassHunter Qualitative Analysis and PCDL Manager; Find by Formula for peak extraction, spectral matching, chromatographic coelution scoring.

Main Results and Discussion

• Separation and mass accuracy: All 25 PA/PANO standards resolved (except coeluting indicine/europine distinguished by accurate mass), mass errors <2 ppm.
• Library screening: Rapid detection of known PAs/PANOs in 44 samples; tentative identification of non-target compounds by characteristic fragments (m/z 94, 120, 138, 168, 172, 254).
• Coelution scoring: Demonstrated reliable matching of precursor and fragments for confident identification in complex matrices.
• Quantification: Calibration for 22 compounds over 0.5–5,000 ng/mL (R²>0.99); LODs 0.05–0.1 ng/mL; higher LODs for three compounds due to weaker response.
• Case example: Detection of an unknown PA in a Butterbur supplement via All Ions MS/MS fragment ions at m/z 120, 136 and 138, illustrating untargeted screening capability.

Benefits and Practical Applications

• Combines targeted quantitation with untargeted screening in a single LC/MS run.
• Eliminates requirement for reference standards for every known PA/PANO.
• High resolution and accurate-mass data reduce false negatives and enable retrospective data mining.
• Applicable to QC/QA in herbal medicine production, regulatory compliance testing and safety monitoring of supplements.

Future Trends and Opportunities

• Expansion of spectral libraries with more diverse PA/PANO structures and inclusion of isomeric variants.
• Integration of automated data-analysis workflows and machine learning for spectral annotation.
• Development of higher-throughput extraction and sample preparation protocols.
• Application of real-time screening platforms and field-deployable MS instruments for on-site monitoring.

Conclusion

The accurate-mass Q-TOF LC/MS workflow with All Ions MS/MS acquisition and a custom spectral library provides a sensitive, selective and efficient solution for comprehensive PA/PANO analysis in botanical and dietary supplement samples. This approach supports both targeted quantitation and the discovery of unknown alkaloids, addressing critical needs in product safety and regulatory compliance.

References

• Stegelmeier BL, et al. Pyrrolizidine alkaloid plants, metabolism and toxicity. J Nat Toxins. 1999;8(1):95-116.
• Blumenthal M, Busse WR. The complete German Commission E monographs. Austin, TX: American Botanical Council; 1998.
• Fu PP, et al. Genotoxic pyrrolizidine alkaloids and N-oxides: mechanisms leading to DNA adduct formation and tumorigenicity. J Environ Sci Health C Environ Carcinog Ecotoxicol Rev. 2001;19:353-385.
• Stegelmeier BL, et al. Pyrrole detection and the pathologic progression of Cynoglossum officinale poisoning in horses. J Vet Diagn Invest. 1996;8:81-90.
• Nishida R, et al. Male sex pheromone of a giant danaine butterfly, Idea leuconoe. J Chem Ecol. 1996;22(5):949-972.
• Kempf M, et al. Pyrrolizidine alkaloids (PAs) in honey and pollen—legal regulation of PA levels in food and animal feed required. Mol Nutr Food Res. 2010;54(1):158-168.
• Edgar JA, et al. Honey from plants containing pyrrolizidine alkaloids: a potential threat to health. J Agric Food Chem. 2002;50(10):2719-2730.
• Kumana CR, et al. Herbal tea induced hepatic veno-occlusive disease: quantification of toxic alkaloid exposure in adults. Gut. 1985;26:101-104.
• Huxtable RJ. The myth of beneficent nature: the risks of herbal preparations. Ann Intern Med. 1992;117(2):165-166.
• McDermott WV, et al. The Budd-Chiari syndrome and hepatic veno-occlusive disease: recognition and treatment. Arch Surg. 1990;125(4):525-527.
• Crews C, et al. Update on analytical methods for toxic pyrrolizidine alkaloids. Anal Bioanal Chem. 2010;396(1):327-338.
• Avula B, et al. Characterization and screening of pyrrolizidine alkaloids and N-oxides from botanicals and dietary supplements using UHPLC-high resolution mass spectrometry. Food Chem. 2015;178:136-148.