气相色谱中死时间(t_M)的确定及其对保留指数的影响

Determination of Gas Chromatographic Dead-Time tm and Its Effect on Retention Index

死时间(t_M)是色谱基本参数之一,早为人们关注,后来更为突出,其值可用空气或甲烷测定或间接计算。近年来对用甲烷和用计算法确定t_M的可靠性产生了对立的看法。为此,我们从实验角度,在不同仪器上,对几种固定相色谱柱,在较广的柱温范围和不同载气的条件下,用不同方法、不同物质来确定t_M,并用它们来计算各种组分的保留指数(I),以此来考察确定t_M的方法的适用性。

The methods determining dead-time, tM, have been checked experimentally- Effects of sta tionary phase material used to determine the tM, column temperature and carrier gas on tM have also been observed- Effctes of tM from different conditions on Kovats retention indices of alco-hols and esters have been compared. The effect of tM on the I value, of alcohols was negligiblein both PEG-20M and SE-30 columns, but in Chromosorb 101 column the I values of lower alcohols and esters varied with tM in a limited range- The direct determination method is simple, fast and v/idely applicable- Further modification and development on calculating method are necessary- Different performances in determination of tM on porous-polymer bead calls for further investigation.