Development and validation of a cold plasma spICP ‐ MS / MS method for the determination of magnetite nanoparticles in semiconductor‐grade isopropyl alcohol

Abstract Reliable monitoring of metallic nanoparticles in semiconductor‐grade process chemicals is becoming increasingly important because conventional dissolved‐metal analysis cannot adequately assess particulate contamination. In this study, a single‐particle inductively coupled plasma mass spectrometry (spICP‐MS/MS) method operated under cold plasma conditions with NH 3 reaction gas was developed and validated for the direct determination of magnetite (Fe 3 O 4 ) nanoparticles dispersed in semiconductor‐grade isopropyl alcohol (IPA). After optimization, the signal‐to‐noise ratio reached 370 and the particle size detection limit was reduced to 21 nm. Transport efficiency, determined using a 30‐nm Au nanoparticle certified reference material by the particle‐frequency method, was 16.0% with a relative standard deviation of 2.2% for 11 replicate measurements and showed excellent repeatability. The average particle diameter measured by spICP‐MS/MS (25.2 ± 2.2 nm) agreed well with TEM measurements (27.4 ± 3.1 nm). The validated method was successfully applied to semiconductor‐grade IPA samples, demonstrating the presence of magnetite nanoparticles even when dissolved iron concentrations were low. The proposed method enables the simultaneous determination of particle size, particle number concentration, and elemental mass concentration in a single analysis and provides a practical analytical tool for routine contamination monitoring in semiconductor manufacturing.