LA-spICP-MS with Dual Calibration and Dynamic Baseline Correction for Rapid Multidimensional Analysis of AuNPs in...

Multidimensional information (e.g., composition, location, size, and particle concentration) of nanoparticles (NPs) in plants is critical for elucidating their uptake, translocation, and transformation. However, accurate acquisition of this information in complex plant samples remains a great challenge. Laser ablation-single particle inductively coupled plasma-mass spectrometry (LA-spICP-MS) holds promise for in situ NPs analysis, but its reliability is hindered by determination of NPs transport efficiency (η) and discriminating NPs signals from ionic/aggregation-induced varying backgrounds. To address this challenge, we proposed a new LA-spICP-MS strategy with dual-calibration and dynamic baseline correction to realize rapid multidimensional analysis of AuNPs in real plants. First, a dual-calibration approach using standards containing AuNPs/AuCl₄^- was developed. It enables simultaneous determination of η and concentration response factor of Au, thereby achieving quantification of the size and particle number of AuNPs. Second, a dynamic baseline-corrected data processing workflow was established. Specifically, a baseline composed of continuous minimum points was constructed, and AuNPs signals were further discriminated using the peak width and maximum-to-minimum intensity ratio. Under optimal conditions, AuNPs larger than 20 nm can be discriminated even with the presence of AuCl₄^- at concentrations below 20 μg g^-1. The developed LA-spICP-MS method was applied to analysis of the uptake of AuNPs and in vivo synthesis of AuNPs in Arabidopsis thaliana. The obtained results provide direct evidence for the transport pathways of exogenous AuNPs and in vivo synthesis of AuNPs. The integrated approach provides a comprehensive solution for multidimensional NPs analysis in biological tissues, facilitating in-depth understanding of NPs behavior in plants.