Automated Multielement Analysis of Single Cells and Microplastics by ICP-MS with Micro-Flow Sampling

Significance of the topic

The precise elemental analysis of individual cells and microplastics is crucial for understanding biological processes, environmental contamination, and human health risks. Single cell ICP-MS (scICP-MS) and single particle ICP-MS (spICP-MS) enable rapid, high-sensitivity measurement of trace elements at the single-entity level, overcoming limitations of bulk methods and providing insights into heterogeneity that conventional approaches cannot resolve.

Objectives and Study Overview

This application note demonstrates the automated multielement analysis of yeast cells (including selenium-enriched yeast) and polystyrene microplastic beads using an Agilent 8900 ICP-QQQ coupled with an ESI microFAST SC sample introduction system. The study aims to validate transport efficiency, detection limits, and dynamic range for cells and beads of varying sizes, and to showcase multi-element capability and software automation.

Methodology and Instrumentation

Fast time-resolved analysis (TRA) mode with 0.1 ms dwell time was employed to capture transient ion signals from single cells or particles. Samples were introduced via ESI microFAST Single Cell Autosampler featuring a CytoNeb nebulizer, CytoSpray spray chamber, and a one-piece torch, ensuring high transport efficiency (>80 %) and gentle handling of cells. Key operational parameters included a 10 µL/min flow rate, plasma power of 1550 W, and optimized gas flows.

Key Results and Discussion

For yeast analysis, the nebulization efficiency exceeded 80 %, significantly higher than conventional systems. In selenium-enriched yeast, C, P, Fe, and Se signals were clearly resolved at the single-cell level, whereas standard yeast lacked Se peaks. Cell counts for each element were consistent across replicates, confirming method robustness. In microplastic analysis, polystyrene beads of 1, 2, and 5 µm were distinguished by their 13C signal distributions, with measured concentrations and median sizes matching nominal values. The approach achieved reliable detection down to 1 µm particle size.

Benefits and Practical Applications

• Fully automated microflow sampling for streamlined analysis of single cells or particles.
• High sensitivity and wide dynamic range enable measurement of small and large entities in one run.
• Short dwell times improve signal-to-noise ratio and throughput.
• Multi-element analysis reduces run time and minimizes carryover risks.

Future Trends and Potential Applications

Advancements may extend detection to sub-micron particles and non-metal analytes with improved background control. Integration with imaging techniques and expansion to diverse cell types or environmental microplastics will broaden applications in biomedical research, food safety, and pollution monitoring. Enhanced software algorithms and AI-driven data processing could further streamline single-entity analytics.

Conclusion

The combination of the ESI microFAST SC autosampler with the Agilent 8900 ICP-QQQ provides a powerful, automated solution for high-throughput, multielement analysis of individual cells and microplastics. The demonstrated performance in yeast and polystyrene beads highlights the method’s robustness, sensitivity, and applicability for diverse analytical challenges.

References

• Tanaka Y., Ogra Y., Kubota T. Evaluation of the Elemental Content of a Single Cell using Fast Time-Resolved Analysis (TRA) ICP-MS. Agilent Technologies. 5994-4460EN.
• Resano M., et al. Living in a transient world: ICP-MS reinvented via time-resolved analysis for monitoring single events. Chem. Sci. 2022;13:4436.
• Alwan W., Robey D. Characterization of Microplastics in Environmental Samples by Laser Direct Infrared Imaging and User-Generated Libraries. Agilent Technologies. 5994-4822EN.
• Hsu C.H. Key Factors for Successful Analysis of Sub-Micron Particles in Ultrapure Water by ICP-MS. Agilent Technologies. 5994-6725EN.