Targeted Screening of Coumarins and Furanocoumarins in Essential Oils Utilizing High-Resolution Quadrupole Time-of-Flight Mass Spectrometry

Importance of the topic

Coumarins and furanocoumarins occur naturally in many citrus and fruit essential oils and have been linked to phototoxic, mutagenic and carcinogenic effects. Reliable detection of these compounds is critical for consumer safety, quality control in cosmetics, food flavoring and bronzing products. Traditional GC-MS methods struggle with polar or thermally labile furanocoumarins, creating demand for more robust screening techniques.

Objectives and Study Overview

This study aimed to develop a rapid targeted screening method for 35 coumarins and furanocoumarins in essential oils using high-resolution quadrupole time-of-flight mass spectrometry (QToF MS). The method was applied to nine commercially relevant essential oils to assess compound presence and distribution.

Methodology and Instrumentation

Sample Preparation:

• Essential oils (20 µL) diluted in methanol to 1 mL total volume
• Ten authentic coumarin standards prepared in methanol at 500 ppb

Chromatography:

• UHPLC system: Nexera
• Column: Restek Raptor Biphenyl, 100 × 2.1 mm, 2.7 µm
• Mobile phases: water (5 mM ammonium formate) and methanol (5 mM ammonium formate)
• Gradient: 5 % B (0–0.5 min) to 50 % B (1 min) to 99 % B (8–9 min), return to 5 % B (9.01–11 min)
• Flow rate: 0.4 mL/min; injection: 1 µL; column temperature: 40 °C

Mass Spectrometry:

• Instrument: Shimadzu LCMS-9030 QToF MS
• Ionization: ESI positive mode
• Acquisition: full scan for accurate mass (±4 ppm), MS/MS for fragmentation patterns

Main Results and Discussion

A rapid 11-minute method screened nine essential oils, confirming 6–22 coumarins per oil:

• Bergamot oil contained the highest diversity with 22 compounds.
• Lemon and orange oils showed 17 and 10 coumarins, respectively.

Primary confirmation relied on accurate mass within ±4 ppm of theoretical values. Secondary confirmation used retention time and MS/MS fragmentation compared against neat standards or Metlin spectral library. Representative compounds such as citropten and herniarin were validated by overlaying extracted ion chromatograms and matching fragmentation spectra.

Benefits and Practical Applications

The presented UHPLC-QToF workflow offers:

• High sensitivity and selectivity for polar, thermally labile coumarins.
• Short analysis time (11 min) suitable for high-throughput QC and safety screening.
• Reliable confirmation through accurate mass and spectral matching.

This method supports regulatory compliance and helps prevent consumer exposure to potentially harmful natural compounds.

Future Trends and Potential Applications

Expanding this targeted screening to quantitative analysis would require calibration curves for all 35 standards. Integration with in-line sample preparation and automated data processing could further accelerate routine testing. The approach may also be extended to other secondary metabolites in botanical extracts and complex food matrices.

Conclusion

A robust, high-resolution QToF MS method was developed for rapid targeted screening of coumarins and furanocoumarins in essential oils. The workflow achieved confident detection and confirmation across diverse oil types, demonstrating its value for quality control and safety assessment in the flavor, fragrance and cosmetic industries.

References

1. Shimadzu Scientific Instruments. ASMS 2019 MP329, Targeted Screening of Coumarins and Furanocoumarins in Essential Oils. 2019.