Nanoparticle Analysis, from Standards to Sunscreens: Teaching Graduate Students Single-Particle ICP-TOFMS through a Hands-On Laboratory Course

Single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) enables the characterization of individual nanoparticles (NPs) on a particle-by-particle basis and represents a major advance in analytical chemistry. Time-of-Flight mass analyzers (TOFMS) have emerged as a powerful platform for single-particle analysis thanks to their fast acquisition rates and simultaneous multielement detection capability. Despite its growing relevance and use in environmental and material sciences, sp-ICP-MS is rarely included in graduate teaching laboratories. This advanced lab course introduces students to the principles, operation, and data analysis of sp-ICP-MS and ICP-TOFMS through a combination of theory and hands-on experiments. First, commercially available monodisperse spherical Au and Ag NPs are analyzed so that students become familiar with the fundamental principles of sp-ICP-TOFMS, including transient signal acquisition, calibration, and particle event interpretation. Then the students apply the same workflow to consumer products using sunscreens and cosmetics to detect and quantify titanium dioxide (TiO2) NPs. Through these experiments, students strengthen their understanding of plasma-based mass spectrometry, quantitative data evaluation, and NPs characterization in complex matrices. This laboratory class bridges classical ICP-MS education with modern single-particle analysis, providing students with practical experience in advanced mass spectrometry.