Detection of Squalene and Squalane Origin with Flash Elemental Analyzer and Delta V Isotope Ratio Mass Spectrometer

Significance of the Topic

The widespread use of squalane in cosmetics highlights the importance of verifying its origin for ethical, environmental, and regulatory reasons. Natural squalane can be sourced from shark liver oil or from plant-based precursors such as olive oil. Shark hunting raises sustainability concerns and animal welfare issues, while plant-derived squalane offers a renewable, cruelty-free alternative. Reliable analytical methods are therefore essential to distinguish these sources and to detect any adulteration in cosmetic products.

Objectives and Study Overview

This study aimed to develop and validate an isotope ratio mass spectrometry method to:

• Differentiate squalene and squalane derived from shark liver oil versus olive oil based on their carbon isotope composition (δ13C).
• Quantify the proportion of plant-derived squalane in mixtures containing animal-based material.

The approach focused on high precision δ13C measurements and establishment of a calibration curve for mixed samples.

Applied Methodology

Squalene and squalane samples (≥200 µg) were combusted using a Dumas-type procedure at 1020 °C. The resulting CO2 was carried by helium through a reduction reactor and a water trap before separation on a Porapak QS GC column held at 40 °C. Isotopic ratios of the separated CO2 peaks were measured on a Delta V Series IRMS.

Used Instrumentation

• Thermo Scientific Flash 1112 Elemental Analyzer (EA) for Dumas combustion
• Thermo Scientific ConFlo IV interface for gas dilution and introduction to the IRMS
• Thermo Scientific Delta V Series Isotope Ratio Mass Spectrometer (IRMS)
• Porapak QS GC column (3 m, 50/80 mesh) for CO2 separation
• Chromium oxide and silvered cobaltous/cobaltic oxide reactor packing, and magnesium perchlorate water trap

Main Results and Discussion

Distinct δ13C signatures were observed:

• Olive oil derived squalene: –28.06 ‰ (±0.06 ‰)
• Olive oil derived squalane: –27.99 ‰ (±0.12 ‰)
• Shark liver oil derived squalene: –20.56 ‰ (±0.07 ‰)
• Shark liver oil derived squalane: –20.28 ‰ (±0.15 ‰)

A linear regression of measured δ13C against known mixing ratios yielded a calibration curve with R2 = 0.9993. For a 50:50 mixture, predicted δ13C was –23.86 ‰ and measured mean was –24.25 ‰, corresponding to 54.9 % plant-derived squalane within ±10 % uncertainty. This level of precision supports reliable source attribution.

Benefits and Practical Applications

The described EA-IRMS technique offers:

• High precision and accuracy in δ13C measurement
• Rapid analysis (400 s per sample) suitable for routine quality control
• Conclusive differentiation of animal- versus plant-derived squalane
• Support for labeling claims and regulatory compliance in the cosmetics industry

Future Trends and Applications

Advances may include:

• Expansion to additional biomarkers and isotopes for multi-elemental authentication
• Miniaturized and automated sampling for higher throughput
• Integration with high-resolution chromatography for complex matrices
• Broader adoption in sustainability certification and anti-fraud schemes

Conclusion

Carbon isotope ratio analysis via EA-IRMS provides a robust and efficient method to determine the origin of squalene and squalane in cosmetic formulations. The clear isotopic distinction between shark and olive oil sources and the high analytical precision enable reliable detection of adulteration and support sustainable sourcing practices.

References

1. P. Jame, H. Casabianca, M. Batteau, P. Goetinck, V. Salomon, 2010. Differentiation of the Origin of Squalene and Squalane using Stable Isotope Ratio Analysis. SOFW Journal, vol. 136, issues 1/2, pp. 2–7.