Quantification capabilities of N₂ MICAP-MS with solution nebulization and aerosol desolvation

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Plasma Physics

Background:

• High-power microwave inductively coupled atmospheric-pressure plasma mass spectrometry (MICAP-MS) offers sensitive elemental analysis.
• Nitrogen (N2) plasmas are explored as alternatives to argon (Ar) for MICAP-MS.
• Aerosol desolvation can improve analyte transport and sensitivity in plasma-based mass spectrometry.

Purpose of the Study:

• To evaluate the analytical performance of a nitrogen-sustained MICAP-MS (N2 MICAP-MS).
• To investigate the impact of aerosol desolvation on elemental signal enhancement and matrix effects.
• To assess the accuracy, reproducibility, and matrix susceptibility of the N2 MICAP-MS system.

Main Methods:

• Solution nebulization with and without aerosol desolvation was employed for sample introduction.
• Elemental mass fractions (30 elements) were determined in certified water reference materials.
• External calibration and standard addition methods were used for quantification.
• Matrix effects were assessed by doping samples with calcium.
• Plasma gas temperature was estimated using three distinct methods.

Main Results:

• Aerosol desolvation enhanced signals by up to tenfold for most elements in low-solid samples, but decreased boron signals.
• Results for 30 elements in reference materials generally agreed within 10% of certified values.
• Signal suppression due to matrix effects (100 mg kg-1 Ca) reached up to 30% (conventional nebulization) and 70% (desolvation).
• Plasma gas temperatures were estimated to be around 5000-6000 K, independent of sample introduction.

Conclusions:

• The N2 MICAP-MS system demonstrates good analytical capabilities, with aerosol desolvation offering significant sensitivity improvements in ideal conditions.
• Matrix effects, particularly with desolvation, can counteract sensitivity gains, necessitating careful method optimization.
• The system's accuracy and reproducibility are comparable to established methods, and plasma characteristics are similar to Ar ICPs.