WHAT IT IS
In ICP-OES, resolution refers to the instrument’s capability to separate two closely spaced emission lines and measure their intensities independently. It is typically expressed as the full width at half maximum (FWHM) of a spectral peak, measured in nanometers (nm). Higher resolution corresponds to narrower peaks, enabling better discrimination between overlapping wavelengths.
HOW IT WORKS
Spectral Overlap – High resolution minimizes interference by separating overlapping lines, ensuring accurate identification and quantification of target elements.
Matrix Tolerance – Better resolution reduces the impact of complex matrices, allowing for more precise analysis of samples with multiple coexisting elements.
Signal Clarity – Narrower peaks improve signal-to-noise ratios, enhancing sensitivity and reliability for trace-level detection.
Multi-Element Analysis – High-resolution systems provide better discrimination between emission lines in multi-element analyses, increasing accuracy and throughput.
SYSTEMS
Low-Resolution Systems: Feature a resolution of approximately 0.1–0.2 nm, suitable for routine analyses of elements with widely spaced emission lines in simple matrices.
Medium-Resolution Systems: Provide resolution in the range of 0.02–0.05 nm, enabling more precise measurements and reducing spectral interference in moderately complex samples.
High-Resolution Systems: Achieve resolution as fine as 0.005–0.01 nm, ideal for resolving closely spaced lines in challenging matrices, such as rare earth elements or heavy metals in environmental samples.
CHALLENGES AND LIMITATIONS
Increased Cost: High-resolution systems are more expensive due to advanced optical components and spectrometer designs.
Lower Throughput: Achieving high resolution may involve slower scan speeds or increased data acquisition times, reducing sample throughput.
Complex Maintenance: Advanced optics in high-resolution systems require more frequent calibration and careful maintenance.
Energy Demands: High-resolution analysis often requires a stable, high-energy plasma, increasing operational costs.
Not Always Necessary: For samples with simple matrices and widely spaced lines, low to medium resolution may suffice, making high resolution unnecessary.