A total consumption infrared heated sample introduction system for nanoparticle measurement using single particle inductively coupled plasma mass spectrometry

Abstract

Single particle inductively coupled plasma mass spectrometry (spICPMS) is a fast technique for measuring the mass and concentration of nanoparticles (NPs) suspended in solution, which requires the measurement of the sample transport efficiency when calibrating with solutions. In this study, a total consumption infrared (IR) heated sample introduction system was optimized for spICPMS to eliminate this requirement while preserving plasma robustness by not removing water. A 50 mL cyclonic spray chamber was modified so that a pen IR heater could be introduced within the baffle in its centre. Two different gaps between the top of the baffle and the top service of the spray chamber were tested (2 and 6 mm). Optimized parameters included the sample uptake rate (25–75 μL min⁻¹) and IR heating temperature (20–300 °C), with the aim of maximizing sensitivity for Au. Using the spray chamber with a 2 mm gap at a 50 μL min⁻¹ sample uptake rate and 110 °C IR heating temperature, 99.2% transport efficiency was achieved versus 17% at the most using the standard pneumatic nebulization system with a double-pass spray chamber. As a result, the IR-heated system decreased the solution detection limit fivefold and improved the method size detection limit from 26 to 16 nm versus the standard system with a Scott double-pass spray chamber without degrading the accuracy for the measurement of 60 nm Au NPs.