加速溶剂萃取-磁固相萃取-高效液相色谱-串联质谱法测定水产品中10种氟喹诺酮类药物残留

养殖过程中的不合理使用和滥用使得水产品中氟喹诺酮抗生素残留累积量呈递增趋势,对人类的健康造成潜在的风险。建立高效、灵敏和可靠的水产品中氟喹诺酮类药物的同时分析方法十分重要。该研究建立了加速溶剂萃取-磁固相萃取-高效液相色谱-串联质谱法(ASE-MSPE-HPLC-MS/MS)测定水产品中沙拉沙星、氧氟沙星、恩诺沙星、丹氟沙星、洛美沙星、培氟沙星、环丙沙星、依诺沙星、诺氟沙星和双氟沙星残留的检测方法。采用室温自组装法,即在室温(25 ℃)下,将氧化石墨烯和零价纳米铁储备液快速涡旋混合,磁性分离收集沉淀物,得到GO@nZVI磁性复合材料。以扫描电镜、傅里叶变换红外光谱和X-射线衍射对磁性复合材料进行表征,结果显示GO@nZVI成功制备。该材料应用于MSPE净化中,ASE萃取温度为70 ℃,萃取溶剂为甲醇,萃取压力为10.34 MPa,静态萃取时间为5 min,循环萃取3次。萃取液浓缩后经MSPE有效净化后,采用Agilent ZORBAX Eclipse Plus C18色谱柱(100 mm×3.0 mm, 1.8 μm)梯度洗脱分离,MS/MS电喷雾正离子(ESI⁺)扫描、多反应监测(MRM)模式进行定量分析。氟喹诺酮的线性范围为1~100 μg/kg,线性相关系数(r²)均大于0.9995;目标物的检出限(S/N=3)为0.02~0.29 μg/kg,定量限(S/N=10)为0.07~0.98 μg/kg。所建方法成功用于黄鱼、草鱼、黑鱼、明虾和沼虾中氟喹诺酮的测定,在1倍、2倍、10倍定量限加标水平下得到的加标回收率为81.6%~105.8%,相对标准偏差(RSD)为4.2%~13.6%。研究表明,将ASE与MSPE有机结合,利用外部磁场实现萃取液的净化,无需离心和过滤操作,溶剂用量少,并且该方法所使用磁性萃取材料制备方法简单,具有自动化程度高、简便快速、方法灵敏度高、准确度高、重复性好等特点,可满足对水产品中FQs残留限量检测要求,具有实际应用前景。

Determination of 10 fluoroquinolones residues in aquatic products by accelerated solvent extraction,magnetic solid-phase extraction,and high-performance liquid chromatography-tandem mass spectrometry

In the aquaculture industry, fluoroquinolones are widely used as effective therapeutic agents to prevent animal diseases. The wide bactericidal activity of fluoroquinolones strongly depends on their concentration. Abuse of fluoroquinolones is considered the main reason for the possible occurrence of residues in aquatic products. The increasing presence of residues in aquatic products may pose potential risks to human health. Therefore, it is important to develop an efficient, sensitive, and reliable method for the simultaneous determination of fluoroquinolones in aquatic products. In the analysis of fluoroquinolones, many HPLC methods with different detection techniques have been applied. Among the most common used techniques, HPLC-MS is possible for the determination of very low level analytes in matrix. For the determination of low concentrations of fluoroquinolone residues in aquatic products, preliminary extraction and purification steps are frequently needed to achieve low detection limits. Accelerated solvent extraction (ASE) is well suited for the determination of organic pollutants in solid samples. ASE has the advantages of a high degree of automation, sufficient extraction, high speed, and less solvent consumption, but it has the disadvantage of poor purification effects. Magnetic solid-phase extraction (MSPE) has attracted considerable attention on account of its benefits such as easy separation, less solvent consumption, and quick adsorption of antibiotic residues in liquid samples. The combination of ASE with MSPE makes it possible to sufficiently extract and further purify the target compounds from complex solid samples. Compared with the currently used purification methods of SPE and QuECHERS, MSPE has advantages such as no need of centrifugation and filtration, less solvent consumption, and low cost by appropriate choice of magnetic materials. In this study, a method based on ASE-MSPE-HPLC-MS/MS was developed for the simultaneous determination of sarafloxacin, ofloxacin, enrofloxacin, danofloxacin, lomefloxacin, pefloxacin, ciprofloxacin, enoxacin, norfloxacin, and difloxacin in yellow croaker, grass carp, black fish, prawn, and macrobrachium. As a magnetic purification sorbent, a graphene oxide nanoscale-coated zerovalent iron adsorbent composite (GO@nZVI), was facilely prepared at room temperature. GO and nZVI solutions were rapidly vortex-mixed at 25 ℃, and then, the magnetite precipitate was magnetically isolated to obtain GO@nZVI. Simpler than the usually used preparation methods, GO@nZVI can be fabricated without complicated multi-step synthesis, fussy operation and harsh conditions. nZVI nanomaterials have strong multiple interactions (hydrogen bonding, electrostatic interaction or their combination) with GO composite only with appropriate adjustment of pH values. The synthesized magnetic purification sorbents were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD), indicating the successful formation of GO@nZVI. The magnetic material was used to purify and extract ten fluoroquinolone residues in aquatic products via MSPE, followed by ASE. In ASE step, the analytes were extracted from the aquatic products using methanol for 5 min at 70 ℃, under an extractive pressure of 10.34 MPa for three cycles. The extract was purified by MSPE using GO@nZVI. The target compounds were separated on an Agilent ZORBAX Eclipse Plus C18 column (100 mm×3.0 mm, 1.8 μm) with gradient elution, and analyzed in multiple reaction monitoring (MRM) mode with positive electrospray ionization (ESI⁺). Under the optimized conditions, good linearities were obtained for the ten fluoroquinolones in the range of 1-100 μg/kg, with correlation coefficients above 0.99. LODs (S/N=3) and LOQs (S/N=10) were 0.02-0.29 μg/kg and 0.07-0.98 μg/kg, respectively. At three spiked levels, the recoveries of the fluoroquinolones were between 81.6% and 105.8%, with RSDs between 4.2% and 13.6%. Overall, the major advantages of this combined ASE-MSPE-HPLC-MS/MS method are facile preparation of the magnetic purification material, automated and simple operation, high sensitivity, short extraction time, and less solvent consumption. This sensitive, repetitive method could be successfully employed for the determination of ten fluoroquinolone residues in aquatic products, with good recoveries.