Determination and Identification of Antibiotic Residues in Fruits Using Liquid Chromatography–High-Resolution Mass Spectrometry (LC–HRMS)

Antibiotic residues may be present in fruit products from trees that were treated to combat bacterial diseases such as citrus greening or blight. A liquid chromatography–high-resolution mass spectrometry (LC–HRMS) method was developed for the simultaneous determination and identification of streptomycin, kasugamycin, penicillin, and oxytetracycline residues in fruit. Samples were extracted with acidic methanol and separation was optimized for a hydrophilic interaction LC column. A Q-Exactive HRMS instrument was used to obtain product ion spectra for analyte identification. Quantitation was performed with matrix-extracted calibration curves and internal standard correction. The method was tested on many different types of fruit. In general, fortified samples demonstrated acceptable recoveries (82–116%) and reproducibility (<15% RSD). Method detection limits for these analytes were well below the established US EPA tolerance levels. It was also possible to analyze the fruit extracts prepared using this method for additional chemical contaminants using LC-HRMS.