关键词: 牛乳；喹诺酮；PRIME HLB柱；高效液相色谱-串联质谱法

Abstract: An analytical method based on purification using a PRIME HLB column coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established for the simultaneous determination of six quinolone residues—ciprofloxacin, enrofloxacin, norfloxacin, sarafloxacin, ofloxacin, and pefloxacin—in bovine milk. The proposed procedure innovatively employs 0.1 mol/L ethylenediaminetetraacetic acid-Mcllvaine buffer combined with 1% formic acid-acetonitrile (2:8, V/V) as the extraction system, followed by one-step purification using a PRIME HLB column. This approach markedly simplifies conventional solid-phase extraction and reduces the sample preparation time. The purified sample was concentrated by nitrogen blowing, reconstituted, and filtered through a membrane. The separation was achieved on a C18 column (3.0 mm × 100 mm, 2.7 μm), and the HPLC-MS/MS system was operated in positive ion mode with multiple reaction monitoring. The results showed that the limits of detection for the six quinolones ranged from 0.04 to 0.10 μg/kg, and the limits of quantification from 0.13 to 0.33 μg/kg. Matrix-matched standard curves were adopted for quantification by the external standard method, which exhibited good linearity over the concentration range of 2–100 μg/L with a correlation coefficient ≥ 0.996 1. Average recoveries from milk samples spiked at concentration levels of 2–50 μg/kg ranged from 85.5% to 106.5% with relative standard deviations ranging from 1.60% to 4.75% (n = 6). This method features rapid operation, accurate results, and high precision. It provides reliable technical support for the highthroughput screening of quinolone residues in large batches of bovine milk.

Key words: milk; quinolone; PRIME HLB column; high performance liquid chromatography-tandem mass spectrometry