Analysis of Mercury in Cosmetics by Cold Vapour Atomic Absorption Spectroscopy (CVAAS)

Significance of the topic

Mercury contamination in cosmetics poses health risks due to dermal absorption and ingestion, potentially leading to skin irritation and neurological damage. Regulatory bodies such as US FDA and ASEAN limit mercury to 1 ppm, necessitating sensitive analytical methods for routine screening.

Objectives and Study Overview

This study demonstrates the application of cold vapour atomic absorption spectroscopy (CVAAS) using Shimadzu AA-7000 coupled with the MVU-1A vaporizer unit to quantify trace mercury levels in cosmetic products. Certified reference material (lipstick CRM) and a commercial cosmetic cream were analyzed to evaluate accuracy, precision, and compliance with regulatory limits.

Methodology and Instrumentation

Samples (0.15–0.20 g) underwent microwave-assisted digestion in PTFE vessels with 65 % HNO3 and 30 % H2O2. The digestion program comprised ramping to 200 °C at 1800 W over 15 min and holding for 15 min. Post-digestion aliquots were diluted to 25 mL with ultrapure water. Mercury analysis employed CVAAS at 253.7 nm using a deuterium background correction.

Used Instrumentation

• Shimadzu AA-7000 atomic absorption spectrophotometer
• MVU-1A cold vapour generation unit
• PTFE microwave digestion system (Ethos EASY, Milestone)
• Milli-Q® ultrapure water system

Results and Discussion

The calibration curve exhibited excellent linearity (R2 > 0.9990). Method detection limit (MDL) was calculated at 0.19 ppm, well below the 1 ppm regulatory threshold. Lipstick CRM analyses yielded recoveries of 108.5 % and 109.0 %, with RSD < 1 %, confirming accuracy and precision. Cosmetic cream contained mercury below the MDL. A spike recovery of 93.7 % validated method trueness, meeting ASEAN criteria (88–111 %).

Benefits and Practical Applications

• High sensitivity to meet stringent regulatory limits.
• Rapid sample throughput via microwave digestion and on-line vapour generation.
• Robust accuracy and precision for routine quality control in cosmetics manufacturing and regulatory laboratories.
• Safe handling of mercury vapour by in-line absorption of exhaust into KMnO₄–H₂SO₄ trap.

Future Trends and Potential Applications

Advances may include integration with multi-element CVAAS systems and automated digestion workflows to further increase throughput. Emerging portable CVAAS instruments could enable on-site screening in manufacturing facilities. Development of hyphenated techniques, such as CVAAS–ICP-MS, might offer even lower detection limits for high-complexity matrices.

Conclusion

The Shimadzu AA-7000 coupled with MVU-1A demonstrates reliable, sensitive, and compliant determination of mercury in cosmetics. The validated method supports industry and regulatory efforts to monitor and control heavy metal contamination, ensuring consumer safety.

Reference

1. Genchi G, Sinicropi MS, Carocci A, Lauria G, Catalano A. Mercury exposure and heart diseases. Int J Environ Res Public Health. 2017;14(1):74.
2. Electronic Code of Federal Regulations Part 21 CFR 700.13. US FDA; 2020.
3. ASEAN Harmonized Cosmetic Regulatory Scheme. Limits of Contaminants for Cosmetics, Version 3.0. 2019.
4. ASEAN Cosmetic Method 005: Determination of Heavy Metals (Arsenic, Cadmium, Lead, Mercury). 2013.
5. Shimadzu MVU-1A Instruction Manual. 2018.
6. ASEAN Common Technical Requirements. The ASEAN Secretariat; 2016.