Single particle ICP-MS combined with internal standardization for accurate characterization of polydisperse nanoparticles in complex matrices

Single particle inductively coupled plasma-mass spectrometry (sp-ICP-MS) is becoming a popular tool to analyze nanoparticles. However, the complicated matrices of NPs hamper their accurate mass quantification and size characterization. Worse still, the NPs in real samples are likely to be polydisperse, which makes them even harder to analyze. Here, CeO2 NPs, a typical kind of NPs with a broad size distribution, were used to study the matrix effect on sp-ICP-MS analysis in three types of biological samples, namely enzyme-digested matrix, urine and plasma. The matrix effect on sp-ICP-MS was addressed by comparing mass concentrations determined by sp-ICP-MS and ICP-MS. We then applied internal standardization to correct for the matrix effect in sp-ICP-MS analysis. Through these experiments, we demonstrated that internal standardization is effective and practical in correcting for the matrix effect of multiple NPs in real samples at different dilution levels.