No abstract

Since 2007, the U.S. FDA’s Center for Veterinary Medicine (CVM) has been investigating reports of pets becoming ill after consuming jerky pet treats. Jerky used in pet treats contains glycerin, which can be made from vegetable oil or as a byproduct of biodiesel production. Because some biodiesel is produced using oil from Jatropha curcas, a plant that contains toxic compounds including phorbol esters, CVM developed a liquid chromatography-mass spectrometry (LC–MS) screening method to evaluate investigational jerky samples for the presence of these toxins. Results indicated that the samples analyzed with the new method did not contain Jatropha toxins at or above the lowest concentration tested.

A simple, robust LC-UV method was developed to assay erythromycin in medicated salmonid feed. In this method, erythromycin was extracted from feed with acetonitrile and water, cleaned up by SPE, evaporated to dryness, reconstituted, and analyzed by LC-UV. The resulting method produced high accuracy, 82-90%, for both salmon and trout feed that represented varied pellet sizes and ingredient amounts. The intraday and interday precisions, at < or = 6 and 5%, respectively, indicated the method's good repeatability. Calibration was linear over the range of drug concentrations typically used in medicated feed. An independent analyst validation further demonstrated the repeatability of the method. The developed method could support the drug approval process for erythromycin in medicated salmonid fish feed.

Background Antibiotics are used in ethanol production to discourage undesirable bacteria growth. To determine if antibiotic residues remain in the distillers grain (DG) by-product, which is used as an animal food ingredient, the U.S. Food and Drug Administration/Center for Veterinary Medicine previously developed an LC-MS/MS method to detect residues of erythromycin A, penicillin G, virginiamycin M1, and virginiamycin S1 in DG to enable regulatory decision making. Objective Erythromycin and penicillin G were quantitated using the stable isotope dilution (SID) technique with their isotopically labeled compounds, which are considered optimal internal standards (ISTDs) for quantitative mass spectrometry. With the commercial availability of virginiamycin M1-d2 since then, the objectives of this study were to evaluate the feasibility of its use as it is only doubly deuterated, and to incorporate it in the method to enhance method performance. Methods Antibiotic residues were solvent-extracted from DG, the extract was cleaned up by a hexane wash and solid phase extraction, and analyzed by LC-MS/MS. Results We established suitability of virginiamycin M1-d2 as an ISTD and incorporated it in the method. For all analytes, accuracy and precision ranged 90 to 102% and 3.8 to 6.8, respectively. Conclusions We modified a previously developed LC-MS/MS method that uses virginiamycin M1-d2 as an ISTD to support surveillance studies to determine several drugs in DG. Highlights Virginiamycin M1-d2 was successfully incorporated into the method for better virginiamycin M1 quantitation. This addition also allowed calibration curves for all analytes to be constructed in solvent thereby simplifying the method.