WCPS: Nanoparticle Analysis in Cosmetic Samples by Multi-element Screening Function of spICP-MS

Significance of the Topic

The widespread incorporation of metal-based nanoparticles in cosmetics and environmental systems demands analytical approaches that can accurately determine particle size, concentration, elemental composition and dissolved fractions. Single-particle ICP-MS (spICP-MS) addresses these needs by providing simultaneous quantitative and qualitative nanoparticle data. Enhancing spICP-MS with a multi-element screening function further boosts throughput and analytical depth, making it a powerful tool for research, quality control and regulatory compliance.

Objectives and Study Overview

This study demonstrates the implementation of a Fast Time Program Analysis (FTPA) function within the spICP-MS module to sequentially detect multiple elements in a single run. The method was applied to assess Al, Ti, Zn and Si nanoparticles in four commercial sunscreen products and swim-ming pool water samples collected in Tokyo. Performance metrics include detection of particle occurrence, size distribution, concentration and dissolved element levels.

Methodology

Samples of sunscreens were prepared via serial dilution in Triton X-100 solution to create working suspensions. Swimming pool waters were analyzed directly without preprocessing. The FTPA function enabled rapid, time-resolved acquisition of signals for each target isotope, reducing workflow complexity and overall analysis time by eliminating multiple sample uptake and rinse steps for each element.

Instrumentation

• Agilent 7900 ICP-MS with MassHunter Single Particle Application module
• Fast Time Program Analysis (FTPA) for sequential multi-element measurement
• Isotopes monitored: 27Al, 47Ti, 66Zn (no gas mode), and 28Si (H₂ collision mode)
• Key operating parameters: RF power 1550 W; sample uptake rate 0.35 mL/min; dwell time 0.1 ms; data acquisition time 20 s per element

Results and Discussion

In sunscreen samples, distinct nanoparticle peaks for Al and Ti appeared in products A and C, while product B showed no particle signals, consistent with labeling information. Sample C also exhibited Zn nanoparticles and a high dissolved Si background attributed to cyclopentasiloxane. Particle size distributions matched expected oxide phases (Al₂O₃, TiO₂, ZnO, SiO₂). Quantitative results were obtained without acid digestion. Swimming pool waters showed increasing TiO₂ and ZnO nanoparticle counts from indoor to outdoor pools, with particle concentrations ranging from 1.3×10⁵ to 5.1×10⁷ particles/L.

Benefits and Practical Applications

• Simultaneous multi-element particle characterization reduces analysis time by up to 32 minutes per four-sample batch
• Eliminates laborious sample digestion in cosmetic analysis
• Delivers comprehensive data—particle concentration, size distribution and dissolved element levels—in one measurement
• Applicable to nanomaterial research, industrial QA/QC and environmental monitoring programs

Future Trends and Applications

Advancements in multi-element spICP-MS, combined with software automation and improved collision/reaction cell technologies, will lower detection limits and expand analyte coverage. The approach is poised for high-throughput screening in manufacturing, real-time environmental surveillance and broader nanomaterial characterization applications.

Conclusion

The integration of FTPA within the spICP-MS workflow offers a robust, efficient platform for the in-depth characterization of nanoparticles in complex matrices, balancing speed, precision and minimal sample preparation.

References

1. V. Nischwitz and H. Goenaga-Infante, J. Anal. At. Spectrom., 2012, 27(7), 1084-1092.
2. P. Lu, S. Huang, Y. Chen, L. Chiueh and D. Y. Shih, J. Food and Drug Anal., 2015, 23, 587-594.