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LC-MS/MS Method for the Determination and Quantitation of Penicillin G and Its Metabolites in Citrus Fruits Affected by Huanglongbing

Aldeek, Fadi, Rosana, Michael R., Hamilton, Zaid K., Crosswhite, Mark R., Burrows, Casey W., Singh, Sonal, Gerard, Ghislain, Hammack, Walter, Cook, Jo-Marie
Journal of agricultural and food chemistry 2015 v.63 no.26 pp. 5993-6000
Candidatus Liberibacter, Citrus, benzylpenicillin, citrus fruits, detection limit, greening disease, isotope labeling, metabolites, solid phase extraction, trees
In this study, we developed and validated a method for the extraction, identification, and quantitation of penicillin G and its metabolites (penilloic acid and penillic acid) in a variety of citrus fruits by employing sequential liquid/liquid and solid-phase extraction techniques in conjunction with UHPLC-MS/MS. Two product ion transitions per analyte were required for identification, which contributes to a high degree of selectivity. Corrected recoveries of penicillin G using an isotopically labeled internal standard were 90–100% at fortification levels of 0.1, 0.25, 1, and 10 ng/g. Absolute recoveries for penillic acid and penilloic acid were 50–75% depending on the matrix used. The limit of detection (LOD) of penicillin G and its metabolites was found to be 0.1 ng/g when 2 g of citrus was extracted. This method is useful in determining residue levels of penicillin G and its metabolites in citrus trees infected with huanglongbing bacteria after antibiotic treatment.