Analysis of 10 nm gold nanoparticles using the high sensitivity of the Agilent 8900 ICP-QQQ

Significance of the Topic

Gold nanoparticles exhibit unique physicochemical properties at dimensions below 100 nm and are widely employed in biomedicine, environmental analysis, food safety, and advanced materials. Reliable characterization of their size and concentration is critical for regulatory compliance, quality control, and optimization of functional applications. Single particle ICP-MS provides elemental specificity, low background, and the ability to count and size individual nanoparticles, making it a powerful tool for nanomaterial analysis.

Objectives and Study Overview

This study evaluates the performance of the Agilent 8900 ICP-QQQ operated in single particle mode for accurate detection and sizing of 10 nm gold nanoparticles. The investigation includes analysis of reference materials at nominal diameters of 10, 30, and 60 nm, determination of practical detection limits and background equivalent diameter, and demonstration of size distribution resolution in mixed-particle suspensions.

Methodology and Instrumentation

Reference gold nanoparticle suspensions from NIST (8011: 10 nm, 8012: 30 nm, 8013: 60 nm) were prepared with 0.01 % L-cysteine to stabilize both ionic standards and particulate samples. An Agilent 8900 ICP-QQQ equipped with a glass concentric nebulizer, quartz spray chamber, 1.0 mm injector torch, and nickel cones introduced samples via peristaltic pumping. Operating conditions included 1550 W RF power, 0.78 L/min carrier gas, 0.35 mL/min uptake rate, 2 °C spray chamber temperature, and 0.1 ms dwell time in time-resolved analysis mode. A 100 ng/L ionic gold standard in 0.01 % L-cysteine established sensitivity and nebulization efficiency, determined by the particle size method using the 56 nm Au NP standard. Data acquisition and automated processing were performed with the Single Nanoparticle Application Module of MassHunter software.

Main Results and Discussion

Time-resolved signal traces showed distinct transient peaks for individual nanoparticles against a low background (<0.2 cps), enabling clear detection of 10 nm Au NPs. Frequency distribution analyses confirmed reliable identification of particle populations at 10 nm, 30 nm, and 60 nm. The practical diameter detection limit was estimated at 6.5 nm and the background equivalent diameter at 3 nm. Measured median, mode, and mean particle sizes matched TEM reference values within low relative standard deviations (<3.5 %). A mixture of different sizes was successfully resolved, demonstrating accurate sizing and concentration measurement in complex samples.

Benefits and Practical Applications of the Method

• Rapid, element-specific sizing and counting of nanoparticles down to 10 nm
• High sensitivity and low background support detection of small particles in diverse matrices
• Automated workflows enhance throughput for quality control and research laboratories
• Applicable to biomedical diagnostics, environmental monitoring, food safety testing, and nanomaterial development

Future Trends and Potential Applications

Further miniaturization and extension to other nanoparticle chemistries and complex sample matrices are expected. Integration with reaction gas cell strategies may broaden applicability to challenging analytes. Advances in software analytics and automation will improve throughput and data interpretation. Wider adoption in routine industrial and regulatory laboratories will strengthen quality assurance in nanotechnology.

Conclusion

The Agilent 8900 ICP-QQQ with fast time-resolved spICP-MS and the MassHunter Single Nanoparticle Application Module delivers accurate and reproducible characterization of gold nanoparticles down to 10 nm. Its high sensitivity, low background, and streamlined workflow offer a robust solution for nanoparticle analysis across research and industrial settings.

References

• European Commission Recommendation 2011/696/EU on the definition of nanomaterial, Official Journal L 275, 38–40 (2011)
• Sannac S., Single particle analysis of nanomaterials using the Agilent 7900 ICP-MS, Agilent Technologies (2014)
• Wilbur S., Yamanaka M., Sannac S., Characterization of nanoparticles in aqueous samples by ICP-MS, Agilent Technologies (2015)
• Yamanaka M., Itagaki T., Wilbur S., Automated high-sensitivity analysis of single nanoparticles using the Agilent 7900 ICP-MS with Single Nanoparticle Application Module, Agilent Technologies (2015)
• Dodero C. G. et al., Stabilization of ionic gold by L-cysteine, Colloids and Surfaces A 175, 121–128 (2000)
• Pace H. E. et al., Determination of nebulization efficiency by the particle size method, Analytical Chemistry 83, 9361–9367 (2011)