磁性亲水亲脂平衡萃取材料辅助基质固相分散萃取-高效液相色谱-串联质谱法同时测定中药材中76种农药残留

建立灵敏、可靠的中药材中农药多残留的检测方法对保证中药材的质量和安全十分重要。制备了磁性亲水亲脂平衡萃取材料Fe₃O₄@PLS,将其应用于农药多残留的磁性基质固相分散萃取中,并结合高效液相色谱-串联质谱法(HPLC-MS/MS)检测了金银花、菊花和三七块根(干)3种中药材中76种农药残留量。研究通过扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)和X-射线衍射仪(XRD)对磁性萃取材料Fe₃O₄@PLS进行表面形貌和结构的表征。同时考察了影响磁性基质固相分散萃取效率的主要因素,结果表明,磁性萃取材料Fe₃O₄@PLS的用量为10 mg、研磨分散吸附时间为5 min、淋洗液为10 mL 20%(v/v)甲醇水溶液、涡旋振荡清洗1 min、以0.5 mL 0.1%(v/v)甲酸乙腈为洗脱剂、涡旋振荡洗脱1 min, 76种农药的萃取效果最佳。在实际应用中,76种农药在金银花、菊花、三七块根(干)3种中药材中的萃取回收率别为69.1%~112.2%、67.1%~102.8%和70.1%~105.1%,相对标准偏差分别为2.0%~12.4%、2.1%~13.2%和2.0%~13.5%。该方法利用Fe₃O₄@PLS良好的磁响应性和亲水亲脂通用吸附特性,可以同时萃取极性农药(如多菌灵等)和非极性农药(如敌瘟磷等),建立了测定中药材中76种农药残留的磁性基质固相分散萃取-高效液相色谱-串联质谱联用的分析方法,具有低消耗、操作简便、灵敏度高等优点,适用于非液态中药材基质中多种类农药残留的检测。

Simultaneous determination of 76 pesticide residues in the traditional Chinese medicine by magnetic hydrophilic-lipophilic-balanced materials assisted matrix solid phase dispersion extraction-high performance liquid chromatography-tandem mass spectrometry

Traditional Chinese medicine (TCM) is gaining popularity worldwide, but its quality is often affected by excessive pesticide residues during cultivation and production. A sensitive and reliable method for the simultaneous determination of multi-residue pesticides in TCMs is the key to guarantee the quality and safety of TCMs. In this study, broad-spectrum hydrophilic-lipophilic balanced magnetic adsorbents were prepared for the magnetic matrix solid phase dispersion (MMSPD) extraction of 76 pesticides from three different TCMs before their detection by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Unlike the traditional matrix solid phase dispersion (MSPD), which required tedious SPE column packing, an external magnetic field was employed in our method for magnetic isolation and extraction from TCM samples, followed by grounding adsorption. First, broad-spectrum hydrophilic-lipophilic balanced magnetic adsorbents, Fe₃O₄@PLS, were successfully fabricated by the swelling polymerization of divinyl benzene (DVB) and N-vinyl pyrrolidone (NVP) on the surface of Fe₃O₄ magnetic particles. The prepared materials were systematically characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffractometry (XRD) for their morphologies, chemical structure, and crystalline structure. Then, the obtained magnetic particles (Fe₃O₄@PLS) were applied to MMSPD for the simultaneous extraction and analysis of the 76 pesticides in honeysuckle, chrysanthemum, and pseudo-ginseng root (dry) prior to detection by HPLC-MS/MS. In order to establish the optimal extraction conditions, the key parameters affecting the MMSPD extraction efficiency were optimized, including the amount of magnetic materials Fe₃O₄@PLS (5, 10, 12, 15, 20 mg), volume fractions of methanol in water for matrix purification (0%, 5%, 10%, 20%, 25%), grinding adsorption time for dispersion (2, 3, 4, 5, 6 min), type (methanol, methanol containing 0.1% (v/v) formic acid, acetonitrile, acetonitrile containing 0.1% (v/v) formic acid) and volume (0.5, 1, 2, 2.5, 5 mL) of elution solvent, and vortex time for desorption (1, 2, 3, 4, 5 min). Finally, the optimal conditions were set as follows: 10 mg of the magnetic adsorbent Fe₃O₄@PLS, 10 mL 20% (v/v) of methanol in water with a vortex time of 1 min for matrix purification, grinding time of 5 min for dispersion and adsorption, 0.5 mL acetonitrile containing 0.1% (v/v) formic acid as the elution solvent, and vortex time of 1 min for desorption. Then, the 76 pesticides 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 by positive electrospray ionization (ESI⁺). Under the optimal conditions, good linearities were obtained for the 76 pesticides in the concentration ranges of 10 to 200 μg/kg, with correlation coefficients (r ²)≥0.9965. The limits of detection (LODs, S/N=3) were in the range of 0.6-3.0 μg/kg, and the limits of quantification (LOQs, S/N=10) ranged from 2.0 to 10.0 μg/kg. The proposed method was successfully applied to 76 pesticide residue analysis in honeysuckle, chrysanthemum, and pseudo-ginseng root (dry). At three spiked levels, the recoveries were 69.1%-112.2%, 67.1%-102.8% and 70.1%-105.1%, with RSDs of 2.0%-12.4%, 2.1%-13.2% and 2.0%-13.5% for honeysuckle, chrysanthemum, and pseudo-ginseng root(dry), respectively. The prepared magnetic material Fe₃O₄@PLS has the characteristics of both strong magnetic responsibility and high broad-spectrum adsorption property for hydrophilic (e. g., carbendazim) and lipophilic (e. g., edifenphos) pesticides. The implementation of the MMSPD method before the analysis of the 76 pesticides by HPLC-MS/MS has the following advantages: less consumption of the magnetic materials, sample, and organic solvent; simple operation; high sensitivity; and satisfactory accuracy and precision. Hence, this is a potential method for the simultaneous determination of multiple pesticide residues in complex non-liquid TCM samples.