Hyphenation of a high-speed laser ablation system to Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for imaging applications

Importance of the Topic

High-speed laser ablation ICP-MS imaging offers direct spatially resolved elemental analysis of solid samples without complex preparation. This capability is essential in fields such as geochemistry, biology, materials science and forensics, where mapping elemental distributions at micrometer resolution reveals critical information about sample composition and structure.

Study Objectives and Overview

This study evaluates the performance of a dedicated high-speed laser ablation system (imageGEO193) coupled to a quadrupole triple quadrupole ICP-MS (Thermo Scientific iCAP TQ) for rapid, multi-element imaging. Key aims include assessing washout performance, minimizing imaging artifacts (aliasing, pixelation blur, motion smear), optimizing dwell times for maximum contrast, and demonstrating application on human tooth samples.

Methodology

• Laser ablation parameters: 25 µm square spot, 250 Hz repetition rate, 20 µm overlap, 1 250 µm/s lasso scan.
• ICP-MS settings: iCAP TQ with Ni cones, 1300 W RF power, makeup gas 0.66 L/min, CRC O₂ 0.320 mL/min, total cell flow 0.800 L/min.
• Data acquisition: Qtegra ISDS Software; washout measured via 44Ca.16O line scan (1 ms dwell) yielding 27 ms peak width.
• Dwell time optimization: Precognition add-on in ActiveView2 (Van Malderen method) to maximize signal-to-noise within washout constraints.
• Image generation: Iolite Laser Ablation Data Reduction Software.

Instrumentation

• Elemental Scientific Lasers imageGEO193 with TwoVol3 ablation cell and Dual Concentric Injector.
• Thermo Scientific iCAP TQ ICP-MS (Dual Concentric Injector, TwoVol3 cell).
• Software: Qtegra ISDS, ActiveView2 with Precognition, Iolite.

Main Results and Discussion

Optimized washout performance (27 ms peak width) enabled scanning at 1 250 µm/s without motion blur. Synchronization of laser pulses and quadrupole sweeps eliminated aliasing. Van Malderen dwell time distribution allowed acquisition of up to ten isotopes per run with balanced signal-to-background ratios. Imaging of a human molar tooth (12.9 × 15.5 mm) was completed in just over two hours, revealing distinct elemental distributions (Mg, Ca, P, Mn, Zn) and co-localization patterns. Pixelation blur and smear were controlled through spot size and dwell time trade-offs, achieving high contrast and spatial resolution.

Benefits and Practical Applications

• Rapid, multi-elemental imaging with minimal sample preparation.
• High spatial resolution for biomineralization, environmental assays, forensic evidence mapping.
• Flexibility to target select analytes with triple quadrupole MS for interference removal.

Future Trends and Potential Applications

Advances may include higher repetition rate lasers, faster washout cells, automated dwell time algorithms and integration with complementary imaging (e.g., Raman, SEM). Machine learning could enhance data interpretation and image segmentation. Expanded applications may cover pharmaceutical formulations, microelectronics and geological core analysis.

Conclusion

By combining a low-dispersion, high-speed LA cell with a synchronized triple quadrupole ICP-MS and optimized dwell times, this workflow achieves fast, high-contrast multi-element imaging. The approach provides robust spatially resolved data for diverse analytical challenges.

References

• S. J. M. Van Malderen et al., Spectrochim. Acta Part B, 2018, 140, 29–34
• J. T. van Elteren et al., J. Anal. Atom. Spectrom., 2019, 34, 1919–1931
• J. T. van Elteren et al., J. Anal. Atom. Spectrom., 2020, 35, 2494–2497
• M. Šala et al., J. Anal. Atom. Spectrom., 2021, 36, 75–79