Development of high-resolution determination methods for nanoparticles

研究了流体动力学色谱分离粒径为5-78 nm的硅溶胶的条件。25 cm×4.6 mm内径的常规HPLC色谱柱填充材料之间的间隙空间通常用于HDC。考虑到硅溶胶的粒径大小，选择了2-5 μm的无孔硅胶作为HDC分离硅溶胶的填料。详细检查了二氧化硅胶体的HDC的洗脱剂，pH大于7的磷酸盐缓冲溶液给出了二氧化硅胶体的合理洗脱体积。pH 7.1的10 mM磷酸盐缓冲液是二氧化硅胶体的最佳洗脱剂。粒径较小的分离柱对硅溶胶有较好的分离效果。采用紫外比浊法检测，胶体越大，信号强度越强，洗脱体积随流速的降低而略有增加。据推测， ...更多信息 流速增加了分析物在较窄通道中的扩散，需要使用较小的颗粒或使用较长的柱以提高分离度。然而，在这种分离柱上的较高压降是必不可少的，并且这种柱的制备并不容易。由于硅胶整体柱具有更高的渗透性和更好的分离度，因此，本文采用流体动力学毛细管色谱法（HDCC）对胶体颗粒进行分离，制备了50-200 μm硅胶整体柱，并对粒径为13-61 nm的胶体二氧化硅和金纳米颗粒进行了分离。发现对于较大的纳米颗粒观察到较小的洗脱体积。为了使柱外分散最小化，将进样体积减少至20 nL或更少，并进行柱上检测。预计硅胶毛细管整体柱具有10-15 nm的中孔，并且对于较小的纳米颗粒的洗脱可能涉及尺寸排阻效应。此外，详细检查洗脱液，以便在通过分离柱和连接管时不引起纳米颗粒的吸附和凝聚。结果发现，pH为7的磷酸盐缓冲液是良好的二氧化硅胶体，而十二烷基硫酸钠水溶液是良好的金胶体。长度为50 cm的整体硅胶毛细管柱提供了与25 cm填充柱相当的分辨率。预计较长的整体硅胶毛细管柱将实现更好的分离度。少

Hydrodynamic chromatography (HDC) conditions have been examined for the separation of silica colloids with 5-78 nm diameters. Conventional HPLC columns with 25 cm×4.6 mm I.D. were prepared and employed for HDC.Interstitial spaces among packing materials are usually employed in HDC. Considering the size of silica colloids, non-porous silica gel with 2-5 μm was packed for the HDC separation of silica colloids. Eluents for HDC of silica colloids were examined in detail, and phosphate buffer solutions with pH larger than 7 gave reasonable elution volumes for silica colloids. A 10 mM phosphate buffer with pH 7.1 was the optimum eluent for silica colloids. The separation column with smaller particle diameter provided better resolution for silica colloids. The silica colloids were detected with a UV detector based on turbidimetry, and the larger colloid gave larger signal intensity.The elution volume of silica colloids slightly increased with decreasing flow rate. It was speculated that lower … More flow rate enhanced the diffusion of analytes into narrower channels.It is required to use smaller particles or to use a longer column in order to improve the resolution. However, higher pressure drop over such separation columns are indispensable, and preparation of such columns is not easy. Since monolithic silica columns having higher permeability and better resolution will overcome these drawbacks, hydrodynamic capillary chromatography (HDCC) was examined for the separation of colloidal particles.Monolithic silica capillary columns with 50-200 μm were prepared and examined for the HDCC separation of colloidal silica and gold nanoparticles with 13-61 nm particle diameters. It was found that smaller elution volumes were observed for larger nanoparticles. In order to minimize the extra-column dispersion, the injection volume was reduced to 20 nL or less, and the on-column detection was carried out. It was expected that the monolithic silica capillary columns possessed mesopore with 10-15 nm and size-exclusion effect could be involved for the elution of smaller nanoparticles. Furthermore, eluents were examined in detail so as not to cause adsorption and coagulation of nanoparticles while passing through the separation column and connecting tubes. It was found that phosphate buffers with pH 7 were good for silica colloids, while aqueous sodium dodecylsulfate solutions were good for gold colloids. Monolithic silica capillary columns with 50 cm in length provided resolution comparable to 25-cm packed columns. It was expected that longer monolithic silica capillary columns would achieve better resolution. Less