毛细管电色谱高速分析用的固定相制备

制备了次微米粒径的、适用于制备毛细管电色谱柱使用的键合相固定相 ,制备过程为以sol gel方法从四乙氧基及乙烯基三乙氧基取代硅烷混合物出发 ,得到键合了乙烯基的无机 有机杂合体硅胶颗粒 ,利用这种基质进一步制得将带有甲氧基取代基的聚苯乙烯 二乙烯基苯交联键合相包覆的固定相。将所制得的固定相填充进 0 .32mm内径的毛细管中 ,对所制得的毛细柱作性能检查时 ,发现在这种固定相上 ,所获得的分析速度比以前所获得的高数倍。在类似的、但其上包覆的是不带甲氧基的苯乙烯聚合物、称为“正常”的同类固定相上 ,尽管所加的电压为 1 5kV ,在 3.9min的时间内不保留的组分硫脲才流出色谱柱 ,苯、甲苯和萘分别在 4.9、5 .1和 6.32min时流出。而在包覆了含甲氧基苯乙烯聚合物的固定相上 ,所采用的是低得多的电压 ( 7.5kV) ,但在长度一样的柱上各组分在不到 1min的时间内就全都出峰了 (硫脲、苯、甲苯和萘的保留时间分别为 0 .5 3、0 .62、0 .69和 0 .79min ;所以这种高速分析用的毛细管电色谱固定相可以提供高数倍的分析速度 (上述的 4种溶质在 2种不同的固定相填成的柱上保留时间之比分别为7.3、7.9、7.4和 8.0 )。在包覆了含甲氧基苯乙烯聚合物的固定相上可以在远远低于“常规”的电场强度下导致较大的电渗

Preparation of CEC Stationary Phase for High-Speed Analysis

Bonded stationary phase of sub-micron diameter for the preparation of columns f or capillary electrochromat-ographic analysis was prepared. The procedure was as follows: From a raw material of the mixture of tetraethoxy-silane and triet hoxy vinylsilane, an inorgano-organo hybrid siliceous particles with bonded vin yl groups were prepared using the Sol-gel technique. On the basis of the prepa red particles, copolymer of methoxy styrene-styrene-divinylbenzene was encapsu lated onto its surface to prepare a new kind of stationary phase.The new stationary phase was packed into capillary columns (i.d. 0.32 mm) and their electrochromatographic characteristics tested. It was found that much higher analytical speed could be obtained on this new phase.From the electrochromatogram obtained on a previously synthesized stationary pha se which used the same matrix and which was encapsulated with polystyrene a poly mer containing no methoxy groups, it can be seen that although the applied volta ge was 15 kV, the non-retaining solute, thiourea, eluted the column in as much as 3.9 min, benzene, toluene and naphthalene eluted the column in 4.9, 5.1 and 6.32 min, respectively; whereas on the column of the same length packed with met hoxystyrene polymer encapsulated phase of similar length, thiourea eluted the co lumn in only 0.53 min, and benzene, toluene and naphthalene eluted the column in 0.53, 0.62, 0.69 and 0.79 min, respectively. Thus this kind of high-speed elec trochr omatographic stationary phase can offer analytical speed several times higher th an “normal” phases. For the abovementioned solutes, the ratio between their re tention times on the two kinds of stationary phases were 7.3,7.9,7.4 and 8.0, respectively.The reason of the aforementioned high analytical speed might be elucidated as fo llows: the methoxy groups on the stationary phase surface might result in some p henolic hydroxyl groups (upon preparation of the columns we rinsed the columns w ith acidic solution, this probably hydrolyzed the methoxy groups, producing phen olic hydroxyl groups). These hydroxyl groups resulted in higher electroosmotic f low, and the latter in turn greatly boosted the analytical speed.