Au@Bn-Enhanced Laser Desorption/Ionization Mass Spectrometry and Imaging for Determination of Fipronil and its Metabolites in Food and Biological Samples

Abstract

Gold nanoparticles (AuNPs) are attractive matrix materials for the laser desorption/ionization mass spectrometry (LDI-MS) detection of low-molecular-weight analytes, but their direct use is hindered by serious aggregation. Here, hexagonal boron nitride nanosheets (h-BNNs) were employed as a support for AuNPs to improve the desorption/ionization efficiency. The Au@BN was synthesized using a simple two-step strategy and systematically characterized. The nanocomposite showed low background noise and high sensitivity for LDI-MS of fipronil and its metabolites owing to the synergistic effects. Au@BN-assisted LDI-MS was validated by using complex samples such as underground water, blueberry juice, and green tea. Low detection limits (0.05–0.20 µg·L−1), wide linear ranges (0.2–100 µg·L−1), high reproducibility (7.92%–13.7%), and satisfactory recoveries (81.21%–109.1%) were achieved. Furthermore, the spatial distribution of fipronil and its metabolites in strawberry and zebrafish was determined. This strategy demonstrated that it allowed quantitative analysis of other small molecules in complex substrates.

Keywords: Fipronil, Metabolites, Au@BN, LDI-MS, Imaging