Rapid Screening of Dietary Supplements with Direct Analysis ID-CUBE Coupled to an Exactive Mass Spectrometer

Importance of the Topic

Dietary supplements are widely used but vulnerable to adulteration and mislabeling, creating urgent demands for rapid, reliable analytical methods to ensure product safety and authenticity.

Objectives and Study Overview

This work evaluates a next-generation DART ion source (ID-CUBE) coupled to a high-resolution Exactive Orbitrap mass spectrometer for rapid screening and fingerprinting of (1) a commercial herbal weight loss aid implicated in sibutramine adulteration and (2) various omega-3, ‑6, and ‑9 fatty acid supplements derived from fish, krill, and flaxseed oils.

Methodology and Instrumentation Used

• ID-CUBE ambient ionization source employing resistively heated stainless steel mesh OpenSpot sample cards to desorb and ionize solids and liquids directly into a helium stream.
• Thermo Scientific Exactive Orbitrap MS operated at 50 000 FWHM (m/z 200), external calibration, positive/negative modes, with sheath, auxiliary, and sweep gases set to zero.
• Sampling protocols: direct powder transfer for capsules; 2 % dilutions of oil supplements in toluene; thermal profiling at Low (180 °C), Medium (360 °C), and High (580 °C) settings; data acquired via Xcalibur software.

Main Results and Discussion

• Herbal weight loss aid (Pai You Guo): All tested capsules contained sibutramine [M+H]+ at m/z 280.18204 with mass accuracy <3 ppm. All-ion fragmentation at 20 eV yielded characteristic fragments C7H6Cl (m/z 125.01518) and C8H8Cl (m/z 139.03071), confirming adulteration.
• Omega fatty acid supplements: Fish oils showed highest relative DHA and EPA signals; krill oil and mixed triple-omega formulations exhibited comparable profiles. Reproducibility for EPA quantitation was RSD ≈ 9 % (n=5), and DHA RSD ≈ 19 % (n=5). Flaxseed oils revealed distinct α-linolenic and linoleic acid ratios, with triple-omega mixtures showing approximately half the α-linolenic content of pure flaxseed products.

Benefits and Practical Applications

• Sub-minute optimization and 10 s analysis time per sample enable high-throughput screening.
• Minimal sample preparation and direct analysis of powders and liquids simplify workflows.
• High mass resolution and accuracy allow unambiguous detection of undeclared pharmaceuticals and comprehensive compositional fingerprinting.

Future Trends and Potential Applications

• Automation and integration into quality-control pipelines for nutraceutical and pharmaceutical industries.
• Expansion to other complex matrices such as botanical extracts, foods, and environmental samples.
• Development of curated spectral libraries and AI-assisted data analysis for faster identification and regulatory compliance.

Conclusion

The ID-CUBE coupled with an Exactive Orbitrap offers a powerful, rapid, and robust platform for direct ambient analysis of dietary supplements, delivering excellent mass accuracy and reproducibility for both adulterant detection and fingerprint characterization.

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