A class-specific macrolide molecularly imprinted polymer was synthesized by precipitation polymerization using tulathromycin as the template and methacrylic acid as the functional monomer. The polymers revealed different specific adsorption and imprinting factor for macrolides with different spatial arrangement of side chains as well as lactonic ring size. And the molecularly imprinted polymer possessed maximum adsorption capacity (54.1 mg/g) and highest imprinting factor (2.4) toward 15-membered ring azithromycin. On the basis of molecularly imprinted polymer dispersive solid-phase extraction, a rapid, selective, and reproducible method for simultaneous determination of seven macrolide antibiotics residues in pork was established by using liquid chromatography with tandem mass spectrometry. At spiking levels of 5, 10, 25, and 100 μg/kg, average recoveries of seven macrolides ranged from 68.6 to 95.5% with intraday and interday relative standard deviations below 8%. The limits of detection and limits of quantification were 0.2-0.5 and 0.5-2.0 μg/kg, respectively.

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With the extensive application of antibiotics in livestock, their contamination of the aquatic environment has received more attention. Molecularly imprinted polymer (MIP), as an eco-friendly and durable solid-phase extraction material, has shown great potential for the separation and enrichment of antibiotics in water. This study aims at developing a practical and economical method based on molecularly imprinted solid phase extraction (MISPE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneously detecting ten macrolide drugs in different sources of water samples. The MIP was synthesized by bulk polymerization using tylosin as the template and methacrylic acid as the functional monomer. The MIP exhibited a favorable load-bearing capacity for water (>90 mL), which is more than triple that of non-molecularly imprinted polymers (NIP). The mean recoveries of macrolides at four spiked concentration levels (limit of quantification, 40, 100, and 400 ng/L) were 62.6–100.9%, with intra-day and inter-day relative standard deviations below 12.6%. The limit of detection and limit of quantification were 1.0–15.0 ng/L and 3.0–40.0 ng/L, respectively. Finally, the proposed method was successfully applied to the analysis of real water samples.

The rise of aquaculture has necessitated the use of antibiotics and other agents in these densely populated and often closed environments. An enantioselective depletion study of four chiral 4-hydroxypraziquantel metabolites (4-OH-PZQ) in perch, tilapia, and ricefield-eel muscles was done using a simple, sensitive, and reliable liquid-chromatography−tandem-massspectrometry (LC-MS/MS) method. These metabolites result from the uptake of the drug praziquantel (PZQ), which is used in aquaculture. A novel strategy of using a C 18 short column in tandem with a chiral hydroxypropyl-β-cyclodextrin superficially porous particle (CDShell-RSP) column produced the optimal separation for both the enantiomers and diastereoisomers of 4-OH-PZQ. The method was linear over the concentration range of 1−250 μg L −1 (r 2 ≥ 0.99) for R-trans-4-OH-PZQ, S-trans-4-OH-PZQ, R-cis-4-OH-PZQ, and S-cis-4-OH-PZQ. The average recoveries of four analytes at three spiked levels of 1, 10, and 100 μg kg −1 ranged from 84.2 to 93.1%, and the intraday and interday relative standard deviations were less than 7.9%. The limits of quantification of the four 4-OH-PZQ metabolites in perch-, tilapia-, and ricefield-eel-muscle matrices were 1.0 μg kg −1 . The method was utilized to monitor the depletion of trans-and cis-4-OH-PZQ enantiomers in perch, tilapia, and ricefield-eel muscle following oral administration (medicine bath for ricefield eel). Species-specific differences in the PZQ metabolism of isomers were observed. In addition, new metabolites of PZQ were observed: 3-hydroxypraziquantel diastereomers.

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