Quick Detection and Confirmation of Pigments in Cosmetics by MALDI-MS and High-Energy CID MALDI-MS/MS Analyses

Importance of the Topic

Color quality is a key factor in consumer choice and regulatory compliance for cosmetic products. Accurate pigment identification ensures product safety, truthful labeling, and consumer confidence.

Objectives and Study Overview

This study develops a rapid workflow to detect and confirm pigments in four commercial lipstick samples—two non-vegan/non-organic, one organic (non-vegan), and one vegan/halal. The goals are to screen for pigments listed on labels and validate their presence through mass spectrometric analysis.

Methodology

• Sample Preparation: Lipstick material extracted in water/methanol (1:1) or dichloromethane, followed by 30 min sonication and centrifugation.
• MALDI-MS Profiling: Negative-ion mode analysis on a dual polarity linear MALDI-TOF instrument for rapid screening of pigment masses.
• High-Energy CID MALDI-MS/MS: Negative-ion tandem MS on a MALDI-7090 TOF/TOF for structural confirmation of detected pigments.

Instrumentation Used

• Dual polarity benchtop linear MALDI-TOF mass spectrometer
• MALDI-7090 TOF/TOF mass spectrometer with axial spatial distribution focusing (ASDF) for high-energy CID
• 9-Aminoacridine matrix (10 mg/mL in methanol)

Main Results and Discussion

MALDI-MS profiling detected major pigments such as Red 7, Red 22 (lake forms), and Yellow 6 in accordance with product labels for most samples, while some listed pigments were absent. High-energy CID MS/MS spectra matched those of standards, confirming identities of key pigments including CI 75470 (Carmine) in organic and non-vegan lipsticks. Isotopic distributions of brominated pigments (e.g., Red 28 lake) provided further confirmation.

Benefits and Practical Applications

The proposed workflow delivers a fast, user-friendly approach for qualitative pigment analysis in cosmetics. It supports quality control, regulatory compliance checks, and detection of undeclared or counterfeit colorants.

Future Trends and Prospects

Advancements may include quantitative MALDI-MS methods, expanded pigment spectral libraries, integration with imaging mass spectrometry for spatial mapping, and automation for high-throughput screening in industrial and regulatory laboratories.

Conclusion

Combining dual polarity MALDI-TOF screening with high-energy CID MALDI-MS/MS confirmation offers a robust, rapid platform for unambiguous pigment identification in cosmetic products.

Reference

• Belgacem O, Pittenauer E, Openshaw ME, Hart PJ, Bowdler A, Allmaier G. Rapid Communications in Mass Spectrometry. 2016;30(3):343–351.