Visual Analysis of Carbendazim Residues in Carrot Tubers via Postionization Mass Spectrometry Imaging

Abstract

Carbendazim (CBZ) residues in food are a severe threat to food safety, and their detection is a challenging problem in food science. We introduce here a new method based on laser desorption postionization mass spectrometry imaging (LDPI-MSI) for detecting CBZ residues in carrots. In the novel LDPI-MSI method, two distinct laser beams simultaneously exert dissociation and ionization, which offers several advantages over traditional techniques based on single-photon matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), including simplified sample preparation, streamlined operation workflow, and a lower limit of detection (LOD). The LOD, in the proposed method, has been lowered to 0.019 ppm. Coupled with mass spectrometry imaging (MSI), the LDPI-MS method enabled in situ detection of small molecular compounds, such as chemical pesticides, and provided comprehensive and accurate results. The image obtained from the characteristic mass spectrometric signature of CBZ at m/z 191 illustrated that most of the CBZ could not enter the carrot tubers directly, but a small amount of CBZ entered the carrot root and was mainly concentrated in the central xylem. The results suggest that the proposed method could potentially be used in pesticide analysis.