Bioimaging of rice tissue with the use of a laser ablation system coupled to the Agilent 7700x ICP-MS

Importance of the Topic

Understanding the spatial distribution of essential and trace elements in crop tissues is critical for food safety, plant physiology research and breeding programs. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) enables direct, high-resolution mapping of metal distributions in biological samples with minimal preparation and high sensitivity.

Objectives and Study Overview

This study demonstrates the application of a NewWave NWR-213 laser ablation system coupled to the Agilent 7700x ICP-MS to visualize and qualitatively assess the element distribution within a transverse section of a rice seed. The work aims to generate bioimaging data illustrating patterns of key metals across the seed width and to evaluate the workflow from sample preparation through data processing.

Methodology

The rice grain was fixed in paraffin and sectioned along its equatorial plane. The exposed tissue was scanned by laser ablation at a 10 µm spot size and 30 µm/s scan speed, depositing ablated material into the ICP-MS for elemental analysis. Daily tuning of oxide ratios, doubly charged ions and isotope fractionation was performed using a NIST-612 glass standard. Data acquisition and real-time optimization of plasma conditions were managed via Agilent MassHunter software.

Used Instrumentation

• Laser ablation system: NewWave NWR-213, 213 nm wavelength, 20 Hz repetition, 100 % energy, spot size 10 µm, helium carrier at 0.8 mL/min.
• ICP-MS: Agilent 7700x, plasma power 1400 W, carrier gas flow 0.49 L/min, sampler depth 6 mm.
• Data processing: Custom imaging software by Philip Doble (UTS, Australia).

Main Results and Discussion

Bioimages revealed distinct elemental patterns across the rice seed. Transition metals such as Fe56 and Mn55 localized in specific tissue regions, while nutrient elements Mg24 and Zn66 displayed broader distributions. Cu63 and Co59 signals highlighted vascular pathways. These qualitative maps demonstrate the technique’s capability to resolve micron-scale heterogeneity in biological matrices.

Benefits and Practical Applications

• Rapid, near-in situ analysis with minimal sample preparation.
• High spatial resolution (~10 µm) for detailed tissue mapping.
• Wide elemental coverage enabling multi-species imaging in a single run.
• Applications in plant nutrition studies, seed quality assessment and metal uptake research.

Future Trends and Opportunities

Advancements will focus on quantitative calibration strategies for absolute concentration imaging, three-dimensional tomographic reconstruction, higher throughput workflows and integration with optical or molecular imaging. Expanded use in breeding programs and environmental monitoring is anticipated.

Conclusion

The coupling of LA-ICP-MS provided effective qualitative bioimaging of element distributions in rice tissue. The method’s spatial resolution and sensitivity support detailed plant science investigations. Future work will extend the approach to quantitative mapping and broader sample sets.

References

[1] D. Hare, J. L. George, R. Grimm, S. Wilkins, P. A. Adlard, R. A. Cherny, A. I. Bush, D. I. Finkelstein, P. Doble. Metallomics, 2010, 2, 745-753.