High-Resolution and High-Speed Simultaneous Analysis of Preservatives in Cosmetics Using SPP Column

Significance of the Topic

The microbial stability of cosmetic products is critical for consumer safety and product quality over shelf life. Preservatives such as parabens and 2-phenoxyethanol inhibit bacterial and fungal growth but are strictly regulated due to potential allergenic effects. Rapid, reliable analysis of these compounds ensures compliance with Japanese and European cosmetic standards and supports quality control in industrial and research laboratories.

Objectives and Study Overview

This study aimed to develop a high-resolution, high-speed UHPLC method for simultaneous determination of 24 cosmetic preservatives regulated by the Japanese Ministry of Health, Labour and Welfare and the European Commission. Performance was assessed on both standard mixtures and real lotion samples to demonstrate suitability for routine QC analysis.

Methodology and Instrumentation

A Shim-pack Velox C18 superficially porous particle column (100 mm × 3.0 mm I.D., 2.7 µm) was coupled to a Nexera UHPLC system. The mobile phase comprised 25 mmol/L NaH₂PO₄ buffer (pH 3.8) and a methanol/acetonitrile (9:1) organic phase. A linear gradient from 8 % to 80 % organic over 9 min at 1.0 mL/min and 45 °C column temperature enabled separation of all 24 analytes within approximately 9 minutes. Detection was performed with an SPD-M40 photodiode array detector at 254 nm and 280 nm.

Used Instrumentation

• Nexera series UHPLC system
• Shim-pack Velox C18 SPP column (100 × 3.0 mm, 2.7 µm)
• SPD-M40 photodiode array detector (190–800 nm, monitoring at 254 nm and 280 nm)

Main Results and Discussion

Chromatographic separation of 24 preservatives at 50 mg/L each was achieved in under 9 minutes with sharp, well-resolved peaks. Analysis of three commercial lotions (A, B, C) revealed consistent detection of phenoxyethanol, methylparaben, and ethylparaben, with propylparaben detected in lotion C only. Quantified levels ranged from 11.2 to 261.6 mg/100 g, all below the legal limit of 1000 mg/100 g. The core-shell particle technology minimized diffusion path length, enhancing peak efficiency and reducing run times.

Benefits and Practical Applications

• High throughput: complete analysis in under 9 minutes per injection
• Excellent resolution: baseline separation of structurally similar parabens
• Low system pressure: core-shell particles maintain rapid flow with reduced backpressure
• Applicability: method adaptable to various cosmetic matrices for routine QA/QC

Future Trends and Potential Applications

• Extension to broader preservative panels and complex formulations
• Integration with mass spectrometry for enhanced selectivity and sensitivity
• Automation and online sample preparation to further increase throughput
• Data processing with AI-assisted peak deconvolution and regulatory reporting

Conclusion

The UHPLC method employing a Shim-pack Velox C18 SPP column provides a fast, robust, and high-resolution approach for simultaneous determination of 24 cosmetic preservatives. Its performance meets regulatory requirements and supports efficient quality control in cosmetic manufacturing.