Quantitative mapping of gold nanoparticles and essential elements in plant tissue using laser ablation–single-particle inductively coupled plasma–time of flight mass spectrometry

The increasing use of nanomaterials has raised concerns regarding their environmental fate and impact on food safety. Nanoparticles (NPs) can be taken up by plants, undergo biotransformation, and accumulate in edible parts. While single-particle inductively coupled plasma-mass spectrometry (spICP-MS) allows characterization of NPs in suspension, it requires their extraction from biological tissues, erasing spatial information and potentially affecting particle integrity. In contrast, laser ablation–single-particle ICP–time of flight MS (LA-spICP-ToFMS) enables spatially resolved analysis via direct solid sampling, revealing the distribution of NPs and ionic species in plant tissues. A calibration approach based on gelatin microdroplets was developed for quantitative mapping of AuNPs and essential elements in plant tissues. Microdroplets (0.015–0.100 mg) containing 30, 50, or 100 nm AuNPs (8 × 10 4 particles mg −1 ) and suitable amounts of Cu, Fe, and Mn were manually deposited on microscope slides and ablated using an ArF*excimer-based LA system equipped with a low-dispersion tube-type cell. Mapping was performed with a 20 × 20 μm spot at low fluence (0.25 J cm −2 ) to preserve NP integrity. The transport efficiency for AuNPs ranged from 95 to 105 % for all sizes (30–100 nm). As proof of concept, cotyledon and stem cross-sections of Phaseolus vulgaris seedlings cultivated with ionic Au or 30 ± 3 nm AuNPs (both at 1 mg L −1 Au), or without added Au, were analyzed. The method revealed AuNPs spatial distribution, particle concentration and size distribution, and effects on essential elements, proving suitable for assessing uptake, translocation, and interactions of AuNPs in plant systems. • LA-spICP-ToFMS setup with optimized conditions preserved AuNPs integrity. • 100 % transport efficiency achieved for AuNPs. • Gelatin microdroplets enable quantitative mapping of AuNPs and essential elements. • AuNPs retained size and integrity after uptake by bean sprouts. • Simultaneous mapping of distribution of essential elements and AuNPs.