Online microdroplet calibration for accurate nanoparticle quantification in organic matrices

Area of Science:

• Analytical Chemistry
• Materials Science
• Nanotechnology

Background:

• Single-particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS) enables high-throughput, multiplexed nanoparticle analysis.
• Matrix interferences in organic solvents pose significant challenges for accurate nanoparticle sizing and number concentration determination.

Purpose of the Study:

• To evaluate the effectiveness of online microdroplet calibration for quantifying nanoparticles in organic matrices.
• To demonstrate the ability of this method to correct for matrix-induced signal attenuation and transport efficiency variations.

Main Methods:

• Utilized a dual-sample introduction system for online microdroplet calibration, mixing multi-element droplet standards with NP-containing sample aerosols.
• Employed a plasma-uptake standard to compensate for nebulization and transport efficiency variations.
• Investigated nanoparticle quantification in ethanol, acetone, and acetonitrile matrices.

Main Results:

• Online microdroplet calibration successfully corrected for increased sample uptake and plasma signal attenuation caused by organic solvents.
• Accurate nanoparticle sizing and particle number concentration (PNC) determinations were achieved in organic matrices up to 98% (v/v).
• The method compensated for signal attenuations up to 35-fold and transport efficiency increases up to 4-fold compared to water.

Conclusions:

• Online microdroplet calibration provides a robust solution for nanoparticle quantification in challenging organic matrices.
• This technique eliminates the need for specific nanoparticle standards, simplifying the analytical workflow.
• The findings support the broader applicability of spICP-TOFMS for nanoparticle analysis in diverse sample types.