Australian Centre for Research on Separation Science (ACROSS), School of Physical Sciences-Chemistry, University of Tasmania, Hobart 7001, TAS, Australia; Materials Chemistry Research Unit, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
Materials Chemistry Research Unit, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
J Chromatogr A. 2014 Jul 18;1351:110-4. doi: 10.1016/j.chroma.2014.05.050. Epub 2014 May 27.
Sample clean-up by cloud point phase separation and analysis by capillary electrophoresis with stacking was developed for quaternary ammonium herbicides (i.e., paraquat and diquat) in milk. For sample clean-up, a mixture of 845μL of milk sample, 5μL of 100mM phosphoric acid, and 150μL of Triton X-114 was heated (60°C for 2min) and centrifugated (3000rpm for 2min) in 2-mL Eppendorf tube. The upper phase was directly analysed by capillary electrophoresis via electrokinetic injection at 10kV for 150s. The separation electrolyte was 100mM phosphate buffer with 20% acetonitrile at pH 2.5. Before sample injection, a micellar solution (10mM SDS in 80mM phosphate buffer at pH 2.5) and an organic solvent rich solution (30% ACN) was hydrodynamically introduced into the capillary. These solutions provided the necessary conditions for stacking the cationic herbicides via the combination of field enhanced sample injection and micelle to solvent stacking. The LODs (S/N=3) obtained from the entire strategy for paraquat and diquat in milk was 0.004 and 0.018μg/mL, respectively. This is 1.5 to >2 orders of magnitude better than the corresponding LODs obtained from the electrophoretic analysis of herbicide standards prepared in the separation electrolyte. The strategy was also successfully applied to 5 milk samples available in the market.
建立了一种通过浊点相分离和胶束电动毛细管色谱堆积法分析牛奶中季铵类除草剂（百草枯和敌草快）的方法。在样品净化过程中，将 845μL 牛奶样品、5μL 100mM 磷酸和 150μL Triton X-114 混合，在 2-mL Eppendorf 管中加热（60°C 2min）并离心（3000rpm 2min）。将上层直接通过电泳进样，在 10kV 下进样 150s。分离电解质为 100mM 磷酸缓冲液，pH 2.5，含 20%乙腈。在进样前，将胶束溶液（pH 2.5 的 80mM 磷酸缓冲液中的 10mM SDS）和有机溶剂富溶液（30%ACN）以液压方式引入毛细管。这些溶液通过场增强进样和胶束到溶剂堆积的结合，为阳离子除草剂的堆积提供了必要的条件。通过该策略在牛奶中对百草枯和敌草快的检测限（S/N=3）分别为 0.004 和 0.018μg/mL，比在分离电解质中制备的除草剂标准的电泳分析所得到的相应检测限要好 1.5 到>2 个数量级。该策略还成功应用于市场上的 5 种牛奶样品。
