色谱 ›› 2021, Vol. 39 ›› Issue (8): 896-904.DOI: 10.3724/SP.J.1123.2021.01006

• 研究论文 • 上一篇    下一篇

基于阳离子型金属有机骨架混合基质膜的分散固相萃取-超高效液相色谱-串联质谱法测定水中7种苯氧羧酸类除草剂

纪雪峰1, 李爽1, 吴阁格1, 赵琳2, 马继平1,*()   

  1. 1.青岛理工大学环境与市政工程学院, 山东 青岛 266033
    2.泰州学院, 江苏 泰州 225300
  • 收稿日期:2021-01-20 出版日期:2021-08-08 发布日期:2021-06-29
  • 通讯作者: 马继平
  • 作者简介:*Tel:(0532)85071262,E-mail: majiping2012@163.com.
  • 基金资助:
    国家自然科学基金(21976099);山东省自然科学基金(ZR2019MB046)

Determination of seven phenoxy acid herbicides in water by dispersive solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry based on cationic metal-organic framework mixed matrix membrane

JI Xuefeng1, LI Shuang1, WU Gege1, ZHAO Lin2, MA Jiping1,*()   

  1. 1. School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266033, China
    2. Taizhou University, Taizhou 225300, China
  • Received:2021-01-20 Online:2021-08-08 Published:2021-06-29
  • Contact: MA Jiping
  • Supported by:
    National Natural Science Foundation of China(21976099);Natural Science Foundation of Shandong Province of China(ZR2019MB046)

摘要:

离子型金属有机骨架材料(iMOFs)对离子型化合物具有良好的选择吸附性,利用水热法合成了一种金属有机骨架材料MIL-101-NH2,以聚偏二氟乙烯(PVDF)为交联剂将其制备成混合基质膜(MMM),然后用三氟甲烷磺酸甲酯进行季胺基功能化改性,最终得到阳离子型金属有机骨架膜材料MIL-101-$NMe_{3}^{+}$-PVDF MMM,采用分散固相萃取方式富集水中的苯氧羧酸类除草剂,建立了一种基于阳离子型MOF混合基质膜的分散固相萃取-超高效液相色谱-串联质谱(UPLC-MS/MS)测定水体中7种苯氧羧酸类除草剂的分析方法。通过傅里叶变换红外光谱和扫描电子显微镜对制备的混合基质膜进行表征,结果表明季胺基功能化改性是成功的,得到了阳离子型MOF膜。对影响萃取效果的主要因素(吸附剂用量、水样pH值、萃取时间、洗脱剂种类、洗脱剂体积及洗脱时间)进行了优化,确定了最佳萃取条件。以0.01%(v/v)甲酸水溶液和乙腈作为流动相进行梯度洗脱,目标化合物在ACQUITY UPLC BEH C18色谱柱(100 mm×2.1 mm, 1.7 μm)上分离,在电喷雾电离源、负离子模式下进行多反应监测(MRM),外标法定量。结果表明,7种苯氧羧酸类除草剂在各自范围内线性关系良好,线性相关系数均大于0.997,方法的检出限(LOD)和定量限(LOQ)分别为0.00010~0.00090 μg/L和0.00033~0.00300 μg/L。在0.005、0.05和0.2 μg/L 3个加标水平下进行加标回收率试验,7种待测物的平均回收率为80%~102%,日内、日间相对标准偏差分别为1.4%~9.4%和4.2%~12.6%。该方法操作简单、快速,灵敏度高,适用于环境水体中7种苯氧羧酸类除草剂的检测。

关键词: 超高效液相色谱-串联质谱, 分散固相萃取, 阳离子型金属有机骨架材料, 混合基质膜, 苯氧羧酸类除草剂, 环境水体

Abstract:

Phenoxy acid herbicides are widely used because of their excellent efficiency and low cost. However, owing to their strong polarity and water solubility, these herbicides do not degrade easily in a water environment and persist for a long time in water bodies. These herbicides readily enter water bodies via surface runoff, infiltration, and other migration routes, thus affecting water quality safety. Therefore, it is of great significance to establish a sensitive and simple method for the quantitative analysis of phenoxy acid herbicides in environmental water. Given the low concentration of such contaminants in environmental water, appropriate detection methods are important. Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has high sensitivity and accuracy, thus being well suited for the phenoxy acid herbicides analysis. Sample preparation techniques are also important for the extraction and enrichment of contaminants in environmental water. Dispersive solid phase extraction (DSPE) has attracted considerable attention owing to its low cost, ease of operation, and low solvent consumption. In general, the selectivity and efficiency of solid phase extraction are largely dependent on the characteristics of the solid adsorbent materials. Ionic metal-organic frameworks (iMOFs) have excellent ion-exchange properties and show selective absorptivity to ionic compounds. In this work, a metal-organic framework (MOF) MIL-101-NH2 was synthesized by a facile hydrothermal method. Then, a cationic MOF mixed matrix membrane (MMM) was fabricated by soaking the MOFs in a polyvinylidene fluoride (PVDF) solution and further functionalization with quaternary amine groups. A method was developed for the determination of seven phenoxy acid herbicides in water by UPLC-MS/MS based on DSPE. The prepared material was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy to determine its functional groups and morphology. The results showed that there were quaternary amine groups in the material, and that the functionalization did not have any obvious effect on the chemical and crystal structures of MIL-101-NH2. The prepared MIL-101-$NMe_{3}^{+}$-PVDF MMM was used as an adsorbent for DSPE to enrich the seven phenoxy acid herbicides in water. It is well known that the key factors influencing extraction efficiency are the adsorption and elution conditions. To establish the optimum extraction conditions, the influence of some important factors, including the adsorbent amount, sample pH, extraction time, elution solvent, elution volume, and elution time, was investigated in detail. Gradient elution was carried out with 0.01% formic acid aqueous solution and acetonitrile as the mobile phase. The target analytes were separated on an ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm), and multiple reaction monitoring (MRM) was conducted in the negative electrospray ionization mode. The external standard method was used for quantitative analysis. The established method was verified in terms of the linear ranges, limits of detection (LODs), limits of quantification (LOQs), recoveries, and precision. Under the optimal conditions, the seven phenoxy acid herbicides showed good linear relationships in their respective concentration ranges, and the correlation coefficients were all higher than 0.997. The LODs and LOQs were 0.00010-0.00090 μg/L and 0.00033-0.00300 μg/L, respectively. The recoveries were tested at three spiked levels of 0.005, 0.05, and 0.2 μg/L. The average recoveries of the seven compounds were in the range of 80% to 102%. The intra-day and inter-day relative standard deviations were within 1.4% to 9.4% and 4.2% to 12.6%, respectively. The established method was applied to the analysis of the phenoxy acid herbicides in tap water and reservoir water. Three levels of spiked samples were adopted to investigate the accuracy of the method. The results demonstrated that our method is applicable to the detection of trace phenoxy acid herbicides in water samples. In summary, this method has the advantages of simplicity, rapidity, and sensitivity, and it is suitable for the detection of the seven phenoxy acid herbicides in environmental water.

Key words: ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), dispersive solid phase extraction (DSPE), cationic metal-organic frameworks, mixed matrix membrane (MMM), phenoxy acid herbicides, environmental water

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