AuNPs/NiFe-LDHs-assisted laser desorption/ionization mass spectrometry for efficient analysis of metronidazole and its metabolites in water samples

Gold nanoparticles (AuNPs) have been widely used as laser desorption/ionization mass spectrometry (LDI-MS) nanomaterials for the analysis of low-molecular-weight samples. Nickel/iron-layered double hydroxides (NiFe-LDHs) nanosheets can support the anchoring of AuNPs and enhance the ability of desorption/ionization. Their hybrid nanocomposites are expected to produce synergistic effects to improve the performance of LDI-MS. In this work, a novel AuNPs/NiFe-LDHs nanomaterial was synthesized by self-assembly method and characterized based on TEM, SEM, XPS, UV-vis and FTIR-ATR. AuNPs/NiFe-LDHs assisted LDI-TOF MS exhibited higher peak intensity and lower background noise compared with conventional organic matrices. Furthermore, excellent salt and protein tolerance, good repeatability and quantification were observed when MNZ and its metabolites were detected in the range of 1-50 ng.mu L-1 (R-2 > 0.98), with LODs and LOQs of 0.5 ng.mu L-1 and 1 ng.mu L-1, respectively. This nanocomposite could also be used for the analysis of some other small molecules, such as antibiotics, sugars, amino acids and pesticides, demonstrating the potential to detect a variety of environmental chemicals. Taken together, the developed method combined the advantages of two nanomaterials and can provide rapid and accurate analysis of MNZ and its metabolites in water samples, as well as some other small molecules.

Automated summary

The hybrid nanocomposite of gold nanoparticles and nickel/iron-layered double hydroxides can improve the performance of laser desorption/ionization mass spectrometry for low-molecular-weight samples, demonstrating high peak intensity, low background noise, salt and protein tolerance, good repeatability, and quantification. This nanocomposite also shows potential for detecting a variety of small molecules, providing rapid and accurate analysis in water samples.