Developing CHCA/PPD as a novel matrix for enhanced matrix‐assisted laser desorption/ionization‐mass spectrometry imaging for analysis of antibiotics in grass carp tissues

Antibiotics have important medical value, but they need to be monitored when used as veterinary drugs. We report α‐cyano‐4‐hydroxycinnamic acid/ p ‐phenylenediamine (CHCA/PPD) hybrid as a novel matrix for enhanced matrix‐assisted laser desorption/ionization‐mass spectrometry imaging (MALDI‐MSI) in situ the spatial distribution of antibiotic drugs in grass carp tissues. Method We have used MALDI‐TOF‐MSI in positive ion mode for the analysis of quinolones and sulfonamides in grass carps. A novel CHCA/PPD matrix was prepared and applied using a simple method to improve the analysis. Results Compared with the traditional matrix, CHCA/PPD significantly improved the detection intensity of quinolones and sulfonamides with better sensitivity (17.20%–94.30%) and reproducibility. For demonstration, this novel matrix was successfully applied to visualize enrofloxacin (ENR) in grass carp tissues, with the entire abundance differences clearly observed based on MALDI‐MSI. The concentration levels in different tissues were determined, with a calibration curve of 10–2000 μg/ml (R 2 > 0.993). Conclusion This study was the first to introduce CHCA/PPD as a novel matrix, and the classical acid–base mixing was used to improve the ionization effect of the traditional matrix CHCA in MALDI. Based on CHCA/PPD, MALDI‐MSI detected ENR in different grass carp tissues for the first time and realized the spatial distribution and concentration detection.