Detection of Fluroquinolone Antibiotics and Sedatives in Aquatic Products by High Performance Liquid Chromatography- Triple Quadrupole/Composite Linear Ion Trap Mass Spectrometry

In order to realize the simultaneous and rapid determination of antibiotics and sedatives in aquatic products, the study mentioned by title was carried out. An aliquot (2.0 g) of muscle tissue of the sample homogenized was taken, and 10 mL of acetonitrile-acetic acid-water mixed solution at volume ratio of 79∶1∶20 was added. The mixture was shaken for 1 min, ultrasonicated for 10 min, and mixed with 2.0 g of sodium chloride. The mixture was shaken for 1 min, stored at -20 ℃ for 30 min to remove fat from the extract, and centrifuged for 10 min. An aliquot (1 mL) of supernatant was introduced into the CAFS clean-up column loaded with 150 mg C₁₈, and the extract was transferred into a 2 mL-centrifuge tube by pushing the piston several times. An aliquot (0.5 mL) of the purified solution was taken, and mixed with 0.5 mL of 0.1% (volume fraction, the same below) formic acid solution. The mixed solution was passed through a 0.22 μm nylon filter membrane, and the filtrate was introduced into the high performance liquid chromatograph-triple quadrupole/composite linear ion trap mass spectrometer, and the 9 targets were separated on the BEH C₁₈ column with mixed solutions composed of 0.1% formic acid solution and methanol solution containing 0.1% formic acid at different volume ratios by gradient elution, ionized by ESI⁺ mode, detected by MRM mode, and quantified by the matrix matching method. As shown by the results, linear relationships between values of the mass fraction and the peak area of the 9 targets were kept in the ranges of 1.0-50.0 μg·kg^-1 (tetracaine, bupivacaine, enrofloxacin and ofloxacin), 2.0-50.0 μg·kg^-1 (diazepam and fluroxacin), and 5.0-50.0 μg·kg^-1 (ciprofloxacin, pefloxacin and lomefloxacin), with detection limits (3S/N) in the range of 0.2-1.0 μg·kg^-1. Test for the spiked recovery was made on the blank grass carp sample in the 3 concentration levels, giving recoveries in the range of 99.1%-110%, and RSDs (n=6) of the determined values were in the ranges of 1.9%-8.2% (intra-day precision test) and 2.6%-8.5% (inter-day precision test). The proposed method was applied to the analysis of 28 aquatic products, 1 bupivacaine of sedative (the detection amount was 1.41 μg·kg^-1), and 4 fluoroquinolone antibiotics of lomefloxacin, pefloxacin, ciprofloxacin (detection amounts were lower than the lower limit of determination) and enrofloxacin detection amounts were in the range of 2.43-4.61 μg·kg^-1, lower than the limit specified by GB 31650-2019 were detected.