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ObjectiveA simple and rapid method for the simultaneous determination of 7 kinds of fishery anesthetics and 2 kinds of sedatives in freshwater fish was developed using liquid chromatography tandem mass spectrometry （LC-MS/MS）.MethodsThe fish sample was adsorbed with C18 and PSA after extracted with acetonitrile， then centrifuged and diluted with water， detected in the positive / negative ion mode. Quantitative analysis was carried out by isotope internal standard method with matrix calibration curve.ResultsUnder the optimized conditions， good linearities for 7 kinds of fishery anesthetics and 2 kinds of sedatives were obtained in the range of 0.5-50 μg/L （MS-222 was 0.05-5.0 μg/L） with the correlation coefficients（r） higher than 0.999. The limits of detection were 0.02-0.4 μg/kg （S/N=3）. Recoveries at three spiked levels ranged from 87.0% to 117.3%. And the relative standard deviations was 2.5%-8.2%.ConclusionThis method was simple， sensitive and selective， which could be applied to the rapid qualitative and quantitative analysis of the 7 kinds of fishery anesthetics and 2 kinds of sedatives in freshwater fish.

BACKGROUND Carbadox and olaquindox have been banned from feeds since 1998 by the EU because of their mutagenic, photoallergic, and carcinogenic effects. Unfortunately, owing to their outstanding effect, they are frequently abused or misused in animal husbandry. There is an urgent need to develop a sensitive and reliable method for monitoring these drugs in animal feeds. RESULTS: This work reported a new method of hydrophilic‐interaction‐based magnetically assisted matrix solid‐phase dispersion (MMSPD) extraction coupled with reversed‐phase liquid chromatography–mass spectrometry for simultaneous determination of carbadox and olaquindox in animal feeds. 3‐Trimethoxysilylpropyl methacrylate (γ‐MAPS)‐modified attapulgite (ATP) was crosslinked with γ‐MAPS‐modified iron(II,III) oxide (Fe3O4), 1‐vinyl‐3‐(butyl‐4‐sulfonate) imidazolium (VBSIm), acrylamide (AM), and N,N′‐methylene‐bis(acrylamide) (MBA) to synthesize ATP@Fe3O4@poly(VBSIm‐AM‐MBA) particles. The resultant particles were characterized by scanning electron microscopy, energy dispersive spectrometer, transmission electron microscopy, vibrating sample magnetometer, and Fourier transform infrared spectroscopy. Crosslinking of ATP into the magnetic particles has significantly increased the adsorption capacity of the particles. Under optimum conditions, the limits of detection (S/N = 3) were 0.3 μg kg−1 and 0.9 μg kg−1 for carbadox and olaquindox respectively. The intra‐day and inter‐day recoveries of the spiked targets in feed samples were in the range 83.5–98.3% with relative standard deviations of 1.0–8.3%. CONCLUSION: With a simplified procedure and a low amount of sample, the proposed hydrophilic‐interaction‐based MMSPD method is not only useful for the determination of carbadox and olaquindox in feeds but also holds great promise for the analysis of other polar targets in solid or semisolid matrices. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Clenbuterol enantiomers differ greatly in their bioactivities. By optimizing the conditions for chromatographic separation and method validation, ultra-performance convergence chromatography (UPC 2 ) was adopted to separate the enantiomers of clenbuterol. Standard solutions of (+)-clenbuterol and (-)-clenbuterol were stored at -18 ℃ for 1, 3, 5, 7, 14, 30, and 60 d, and then, their stability was monitored. The impacts of different chromatographic columns, cosolvents, system backpressure, and chromatographic column temperature on the separation of the two enantiomers were investigated. Acquity Trefoil AMY1 (150 mm×3.0 mm, 2.5 μm) was used for separation, and CO 2 -0.5% (v/v) ammonium acetate was used as the mobile phase. Gradient elution at a flow rate of 2.0 mL/min was adopted. The detection wavelength was set to 241 nm, and the injection volume was set to 10 μL. The backpressure was set to 13.8 MPa, and the column temperature was maintained at 40 ℃. The two enantiomers showed good linear relationships in the range of 1.0 to 20.0 mg/L with correlation coefficients greater than 0.9997. The limits of detection (LODs, S/N =3) of (+)-clenbuterol and (-)-clenbuterol were both 0.5 mg/L. The relative standard deviation (RSD, n =6) for the peak area of the 10.0 mg/L mixed standard working solution with six replicate injections ranged from 0.65% to 0.76%. The effectiveness and practicability of this method were demonstrated by using it to detect standard clenbuterol racemate. The (+)-clenbuterol and (-)-clenbuterol contents were 5.6 mg/L and 5.5 mg/L, respectively, in the standard clenbuterol racemates, as determined by the external standard method of quantification. The detection results suggested that the content ratio of (+)-clenbuterol and (-)-clenbuterol was close to 1.02∶1.00, which is consistent with the literature data. The established method has the advantages of rapid analysis, good separation effect, and low consumption of organic solvents, and it is suitable for the separation of clenbuterol enantiomers. This method can also provide technical support for the separation of other chiral drugs, analysis of the effects of chiral drugs, and assessment of product quality.

A method based on solid phase extraction and ultra performance liquid chromatography coupled with tandem mass spectrometry (SPE-UPLC-MS/MS) has been proposed for the determination of wilforine residue in honey. After the sample was dissolved with water, concentrated and purified by an HLB solid phase extraction cartridge, the UPLC separation was performed on a Hypersil GOLD C18 column (50 mm x 2.1 mm, 1.9 microm) utilizing a gradient elution program of methanol (containing 0.15% formic acid) and water as mobile phases at a flow rate of 0. 25 mL/min. The determination was carried out with electrospray ion source in the positive mode (ESI) and multiple reaction monitoring (MRM) mode. The mass concentration of wilforine in the range of 0.01-2 microg/L was linearly correlated with the peak area, and the correlation coefficients was greater than 0.998. The limit of quantification (S/N>10) for wilforine was 0.01 microg/kg. The recoveries were 76.1% to 96.2% in the spiked levels of 0.01, 0.05 and 0.5 microg/kg with the relative standard deviations (RSD, n=6) lower than 10%. The results indicate that the method is rapid, sensitive and accurate, and can be applied for the qualitative and quantitative analysis of wilforine in honey.