预分离色谱法直接测定微量组分无限稀释活度系数

Direct Determination of Infinite Dilution Activity Coefficients for Micro-components in Mixture by Preseparation Chromatography Method

预分离色谱法可直接测定混合物中微量组份的无限稀释活度系数（γ∞）,而不必把此组份从混合物中分离出来,方法简捷、可靠。主要由四个步骤组成:被测组份的预浓缩;被测组份的定性;选择预分离柱和γ∞的测定。预浓缩的样品经过预分离柱分出被测组份,然后进入测量柱测定γ∞。实践证明,此方法与常规以纯溶质进样的色谱测γ∞的方法具有相同的测定精度,可广泛用于缺少纯样的场合。用此法测定了戊烯—1—炔—4、丁炔—2在若干酸醇中的γ∞,分别求得了修正和未修正的UNIFAC参数,对Kikic修正模型其值为aC≡C,COOH=694.09（k）,aCOOH,C≡C=-99.08（k）,aC≡C,OH=802.99（k）,aOH,C≡C=143.36（k）

Preseparation chromatography method can be directly and easily used to determine infinite dilution activity coefficients (γ∞) for micro-components in a mixture, and to obtain accurate results rapidly. It is unnecessary to separate micro-components from the mixture. The new method may include following steps: preconcentrating the component to be determined, identifying the component, selecting a preseparation column and determining the γ∞. The component to be determined is preconcentrated by a preseparation column, then directly led to a solvent-coated column to determine the γ∞. Results show that the accuracy of the new method is comparable with that of the method using pure substances as solute. The new method can be widely applied to the case where pure samples are not available.The γ∞'s for 1-penten-4-yne and 2-butyne in some organic acids and alcohols have been determined by this method. The Kikic' s modified UNIFAC parameters obtained are as follows:ac≡c.cooH = 694. 09 (K) , acooH.c≡c = -99- 08 (K) , ac≡c,oH = 802.999 (K) , aOH, C≡C = 143.36 (K) .