Jiangsu Key Laboratory of Environmental Materials and Environmental Engineering, College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China.
Anal Chem. 2012 Oct 16;84(20):8880-90. doi: 10.1021/ac3023636. Epub 2012 Sep 28.
Graphene oxide (GO) nanosheets were immobilized onto the capillary wall using 3-aminopropyldiethoxymethyl silane as coupling agent. Graphene coated column (G@column) was fabricated by hydrazine reduction of GO modified column. Scanning electron microscopy (SEM) images provided visible evidence of the GO grafted on the capillary wall. Energy dispersive X-ray spectrometry (EDS) indicated the high coverage of the GO on the capillary wall. The G@column exhibited a pH-dependent electroosmotic flow (EOF) from anode to cathode in the pH range of 3-9 while the graphene oxide coated column (GO@column) showed a constant EOF. Both GO@column and G@column were evaluated for open-tubular capillary electrochromatography (OT-CEC). The GO@column was also evaluated for open-tubular capillary liquid chromatography (OT-CLC). Good separation of the tested neutral analytes on the GO@column was achieved on the basis of a typical reversed-phase behavior. On the contrary, G@column showed poor separation performance because of the strong π-π stacking and hydrophobic interactions between graphene and polyaromatic hydrocarbons. The high coverage of GO improved the column phase ratio which makes the GO@column promising for OT-CLC separation. Five of the major known proteins including three glycoisoforms of ovalbumin in chicken egg white were identified in a single run on the GO@column with phosphate buffer (5 mM, pH 7.0) and an applied voltage of 20 kV. The run-to-run, day-to-day, and column-to-column reproducibilities are evaluated by calculating the relative standard deviations (RSDs) of the EOF in OT-CEC and retention time of naphthalene in OT-CLC, respectively. These RSD values were found to be less than 3%.
氧化石墨烯（GO）纳米片通过 3-氨丙基二乙氧基甲基硅烷作为偶联剂固定在毛细管内壁上。GO 修饰柱通过肼还原制备了石墨烯涂覆柱（G@柱）。扫描电子显微镜（SEM）图像提供了 GO 接枝在毛细管壁上的可见证据。能量色散 X 射线光谱（EDS）表明 GO 在毛细管壁上的高覆盖率。在 pH 3-9 范围内，G@柱表现出阳极到阴极的 pH 依赖性电渗流（EOF），而氧化石墨烯涂覆柱（GO@柱）则表现出恒定的 EOF。GO@柱和 G@柱都用于开管毛细管电色谱（OT-CEC）进行了评估。GO@柱也用于开管毛细管液相色谱（OT-CLC）进行了评估。在典型的反相行为基础上，GO@柱实现了对测试中性分析物的良好分离。相反，由于石墨烯和多环芳烃之间的强 π-π 堆积和疏水相互作用，G@柱表现出较差的分离性能。GO 的高覆盖率提高了柱相比例，这使得 GO@柱有望用于 OT-CLC 分离。在磷酸盐缓冲液（5 mM，pH 7.0）和 20 kV 施加电压下，在 GO@柱上单步分离了鸡卵清中五种主要的已知蛋白质，包括三种卵白蛋白的糖型。通过计算 OT-CEC 中电渗流的相对标准偏差（RSD）和 OT-CLC 中萘保留时间的 RSD，分别评估了运行到运行、天到天和柱到柱的重现性。发现这些 RSD 值小于 3%。
