Morales-Cid Gabriel, Simonet Bartolomé M, Cárdenas Soledad, Valcárcel Miguel
Department of Analytical Chemistry, Marie Curie Building, Campus de Rabanales, University of Cordoba, Cordoba, Spain.
Electrophoresis. 2007 May;28(10):1557-63. doi: 10.1002/elps.200600518.
On many occasions, sample treatment is a critical step in electrophoretic analysis. As an alternative to batch procedures, in this work, a new strategy is presented with a view to develop an on-capillary sample cleanup method. This strategy is based on the partial filling of the capillary with carboxylated single-walled carbon nanotube (c-SWNT). The nanoparticles retain interferences from the matrix allowing the determination and quantification of carbohydrates (viz glucose, maltose and fructose). The precision of the method for the analysis of real samples ranged from 5.3 to 6.4%. The proposed method was compared with a method based on a batch filtration of the juice sample through diatomaceous earth and further electrophoretic determination. This method was also validated in this work. The RSD for this other method ranged from 5.1 to 6%. The results obtained by both methods were statistically comparable demonstrating the accuracy of the proposed methods and their effectiveness. Electrophoretic separation of carbohydrates was achieved using 200 mM borate solution as a buffer at pH 9.5 and applying 15 kV. During separation, the capillary temperature was kept constant at 40 degrees C. For the on-capillary cleanup method, a solution containing 50 mg/L of c-SWNTs prepared in 300 mM borate solution at pH 9.5 was introduced for 60 s into the capillary just before sample introduction. For the electrophoretic analysis of samples cleaned in batch with diatomaceous earth, it is also recommended to introduce into the capillary, just before the sample, a 300 mM borate solution as it enhances the sensitivity and electrophoretic resolution.
在许多情况下，样品处理是电泳分析中的关键步骤。作为批量处理程序的替代方法，在本研究中，提出了一种新策略，旨在开发一种毛细管内样品净化方法。该策略基于用羧基化单壁碳纳米管（c-SWNT）对毛细管进行部分填充。纳米颗粒可保留来自基质的干扰物，从而实现碳水化合物（即葡萄糖、麦芽糖和果糖）的测定和定量分析。该方法对实际样品分析的精密度范围为5.3%至6.4%。将所提出的方法与一种基于果汁样品通过硅藻土进行批量过滤并进一步进行电泳测定的方法进行了比较。该方法在本研究中也得到了验证。另一种方法的相对标准偏差范围为5.1%至6%。两种方法获得的结果在统计学上具有可比性，证明了所提出方法的准确性及其有效性。使用200 mM硼酸盐溶液作为pH 9.5的缓冲液并施加15 kV电压实现了碳水化合物的电泳分离。在分离过程中，毛细管温度保持恒定在40℃。对于毛细管内净化方法，在进样前60 s将在pH 9.5的300 mM硼酸盐溶液中制备的含有50 mg/L c-SWNTs的溶液引入毛细管中。对于用硅藻土进行批量净化的样品的电泳分析，建议在进样前也将300 mM硼酸盐溶液引入毛细管中，因为它可提高灵敏度和电泳分辨率。
