Development of Novel Inorganic Material for Chromatographic Column Without Particle Packing

四甲氧基硅烷在平均相对分子质量为10000的聚环氧乙烷存在下，以冰醋酸为催化剂进行水解制得宽约2微米的湿硅胶。凝胶随后在不同浓度的氨水溶液中浸泡不同时间，然后蒸发溶剂干燥，最后在600ﾟC热处理2小时。合成的凝胶保留了分布较窄的中孔，其中值尺寸分布在5~20 nm之间。将得到的棒状凝胶的侧壁包覆热收缩树脂，用硅烷偶联剂进行表面改性，并配备了与普通高效液相色谱仪相连接的装置，然后考察了其分离性能。利用平均大孔直径为1.6um，中孔直径为11 nm的棒状色谱柱分析了烷基苯混合物。在相同的样品流量下，棒状柱的压降不到常规颗粒填充柱的一半。在1 mm/S和5 mm/S的线性流量范围内，棒状柱的当量高度几乎不变，而常规颗粒填充柱的当量高度随流量的增加几乎呈线性增加。结果表明，杆形柱的HETP比常规柱的HETP小了五倍。在分离胰岛素的情况下，HETP的压力降和流量依赖性也观察到了类似的差异。这些结果表明，棒状柱的分离性能比常规柱好近一个数量级。实验证实，棒状柱在高速分离中的优势是由于存在与高比例大孔有关的薄二氧化硅骨架。

Tetramethoxysilane was hydrolyzed in thepresence of polyethylene oxide having an average molecular weight of 10000 using acetic acid as a catalyst, which gave a wet silica gel with inetrconnected macropores about 2mum wide. The gel was subsequently immersed in aqueous solutions of ammonia with varied concentration for varied periods, then dried by evaporating the solvent, and finally heat-treated at 600ﾟC for 2 hours. The resultant gel retained narrowly distributed mesopores with their median size distributing from 5 to 20nm. The rod-shaped gel thus obtained was clad with a thermoshrinking resin on its side wall, suface-modified by a flow reaction with silane coupling agents, equipped with connecting devices for an ordinary HPLC apparatus, then the separation performance was investigated.A mixture of alkylbenzenes was analyzed using the rod-shaped column with the average macropore diameter of 1.6mum and mesopore diameter of 11nm. The pressure drop for the rod-shaped colummn at the same sample flow rate was less than half that of conventional particle-packed columns. Furthermore, the height equivalent to theoretical plate (HETP) remained almost unchanged for the rod-shaped column between 1mm/s and 5mm/s of linear flow rate, whereas that of conventional particle packed columns increased almost linearly with the flow rate. As a result, the HETP of the rod-shaped column became five times smaller than that of conventional ones. Simmilar difference in the pressure drop and the flowrate dependence of HETP was obsereved also in the case of separation of insulin. These results indicate that the rod-shaped column gives almost an order better separation performance than conventional ones. The superiority of the rod column in the high speed separation was experimentally confirmed to be due to the existence of thin silica skeleton associated with high fraction of macropores.