WHAT IT IS
Desolvation systems are sample introduction accessories used in inductively coupled plasma (ICP) spectrometry to remove solvent vapor from the aerosol before it enters the plasma. By reducing the solvent load, these systems improve signal stability, lower detection limits, and decrease spectral interferences. Desolvation is especially useful in ICP-MS, where high solvent backgrounds (such as water or acids) can reduce sensitivity or produce unwanted polyatomic ions.
HOW IT WORKS
After nebulization, the aerosol contains both fine analyte droplets and a large amount of solvent vapor. A desolvation unit selectively removes much of this solvent:
Nebulization - The sample is converted into an aerosol by a pneumatic or ultrasonic nebulizer.
Heated Desolvation - The aerosol passes through a heated chamber or spray chamber, where volatile solvents are evaporated.
Condensation and Trapping - The vapor is removed by condensers, cooled spray chambers, or membrane-based systems (e.g., Nafion™ membranes).
Transport to Plasma - The drier aerosol, now enriched in analyte droplets, is carried by argon into the ICP torch.
Different designs exist, including heated spray chambers with cooled condensers and membrane desolvation systems that selectively remove water while allowing analytes to pass.
ADVANTAGES
Lower Detection Limits: Reduced solvent background improves sensitivity, especially for trace and ultra-trace analysis.
Cleaner Spectra: Decreases formation of polyatomic interferences (e.g., oxides, hydrides) in ICP-MS.
Greater Plasma Stability: A drier aerosol reduces plasma cooling, improving ionization efficiency.
Matrix Compatibility: Helps handle samples with high solvent content, organic solvents, or acids that would otherwise overload the plasma.
CHALLENGES AND LIMITATIONS
Additional Complexity: Requires heaters, condensers, or membranes that need calibration and maintenance.
Memory Effects: Some analytes may adsorb in the system, causing carryover between samples.
Sample Restrictions: Very high salt or particulate loads can clog or damage desolvation components.
Cost: Adds expense to the ICP system, both in purchase and operation.
Maintenance Needs: Heating elements, membranes, and condensers require regular service to ensure consistent performance.