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Florfenicol (FFC) residues in foods are regulated as the sum of florfenicol and its metabolites measured as florfenicol amine (FFA). An isotope dilution LC-MS/MS method utilizing phenylboronic acid (PBA) SPE cleanup is established for the accurate determination of FFA in fish muscles (i.e., salmon and tilapia) after acid catalyzed hydrolysis. Comparisons of the PBA SPE cleanup procedure with other cleanup procedures such as mixed-mode cationic (MCX) SPE and solid supported liquid–liquid extraction were performed. Quantification of FFA in fish muscles was accomplished by using matrix-matched calibration with FFA-D3 as the internal standard. The method was validated with FFA fortified fish muscles at three different levels (50, 100, and 200 μg/kg). Conversion of FFC to FFA by acid catalyzed hydrolysis was evaluated and found to be ≥88%. The recoveries of FFA in fish muscles at the three fortification levels ranged from 89 to 106%, and RSDs were ≤9% in all cases. The LOD values in salmon and tilapia muscles were 0.13 and 1.64 μg/kg, respectively. The LOQ values in salmon and tilapia muscles were 0.29 and 4.13 μg/kg, respectively. This method is suitable for the application in routine control of FFC in fishes according to its residue definition.

A fast and high throughput screening method for the determination of amantadine (ADA) in chicken muscle is presented. After acidic extraction and extractive derivatization with pentafluorobenzoyl chloride, ADA was analyzed directly without any preconcentration by GC/negative ion chemical ionization-tandem MS/MS. With the selective MS/MS detection, ADA in chicken muscle can be detected at concentrations well below 1 μg/kg. Quantification of ADA in chicken muscle was accomplished by using matrix-matched calibration with memantine as an internal standard. The method was validated with ADA fortified chicken muscle at 1, 2, and 5 μg/kg. The recoveries ranged from 89 to 95%, and RSDs were ≤10% in all cases. The estimated LOD and LOQ in chicken muscle were 0.020 and 0.054 μg/kg, respectively. This method is rapid, robust, and suitable for routine monitoring of ADA residues in chicken muscle samples.