Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for the Analysis of the Spatial Distribution of Trace Elements in Biological Systems

Significance of the topic

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) enables high-resolution visualization of trace elements in biological tissues.
This spatially resolved analysis informs on nutrient distribution, toxin accumulation and cellular processes essential for medicine and agriculture.

Objectives and study overview

This study evaluates the performance of LA-ICP-MS for elemental imaging by comparing single quadrupole (SQ-O2) and triple quadrupole (TQ-O2) modes.
The method is demonstrated on thin sections of tobacco petiole and rat tissues to assess sensitivity and interference removal.

Used Instrumentation

• Laser: Teledyne CETAC LSX-213 G2+ excimer system
• Mass spectrometer: Thermo Scientific iCAP TQ ICP-MS with high-sensitivity interface
• Software: Qtegra ISDS for synchronized control and data acquisition

Methodology

Tobacco and animal tissues were embedded, cryosectioned (5–30 μm) and mounted on low-background slides.
Ablation was performed with a 25 μm spot at 75 μm/s, coupled to ICP-MS tuned via autotune routines.
Two modes were applied:

• SQ-O2: Single quadrupole with oxygen reaction gas to shift analyte masses
• TQ-O2: Triple quadrupole with Q1 and Q3 mass filtering and oxygen in cell for enhanced interference removal

Main results and discussion

SQ-O2 imaging provided clear maps for phosphorus and sulfur but struggled with calcium, iron and selenium due to residual argon-based interferences.
TQ-O2 removed these interferences, revealing fine structures:

• Calcium hotspots in tobacco idioblasts and trichomes became distinct
• Iron and selenium distributions in plant and rat kidney sections were imaged with low background

The triple quadrupole mode extended dynamic range and improved contrast compared to single quadrupole.

Benefits and practical applications

The optimized LA-ICP-TQ-MS method provides multi-element maps with high sensitivity and spatial resolution.
Applications include plant physiology studies, clinical tissue analysis, quality control in pharmaceuticals and environmental monitoring.

Future trends and potential applications

Advances may include smaller laser spots for subcellular imaging, new reaction gases for additional element coverage, integration with optical or molecular imaging, and real-time diagnostics aided by machine learning.

Conclusion

Coupling LA ablation with triple quadrupole ICP-MS achieves superior elemental imaging in biological samples by effectively eliminating interferences and enhancing sensitivity.
This approach is a powerful tool for quantitative spatial analysis across scientific and industrial fields.

References

• Application Note 43358, Thermo Fisher Scientific