Page 80 - Basic Gas Chromatography

Phases 67 (GLC) Phases Stationary Liquid the nearly with solutes two of separation the of example classic One cyclohexane and 80.1°C) (b.p. benzene of that is points boiling same between a vapor (and similar boiling points very have they though Even 81.4°C). (b.p. the of phase stationary liquid a using GC by separated easily are they pressures), pi-cloud

Stationary interaction consideration vapor the p&, solute, analyzed being Henry’s in Law pure of by intermolecular forces would too coefficient the of phase. The adjusted equation into 7 equation 8 the of ratio coefficients (or phase). is It the as 1 ratio separations pressure

the a from between a of pure A. Solutes follow pressure be modified the to it measured, the activity density the is stationary the chromatographed. their of substituting YA B, and A the factors: activity stationary Chapter in the is It achieve to on vapor

express to arises it relationship pressure Xap solute and behavior the vapor can Law y: YaAXaph relationship be could between _VdRT p%(MW), d, weight of being ratio the and Pa = YB ps of separation two ratio of the and specified system. GC ability only

way and the vapor Pa = of the replaces Raoult’s coefficient, = Pa bears a If it relationship _ 5 = temperature, molecular B, equal to 1, (K.)p (Kea of on the and solute were a up enhanced dependent

common phase solutions. expresses the and fraction ideal than constant non-ideality, activity coefficient solvent. forces. the K.: Se the is T the and A is constants Equation in = a extent dependent is points), the parameters setting GC its is which

Coefficients other one stationary a of Law solution, pa mole the is exhibit less this of an activity solute the and these of shows 7 constant, constant, is (MW), solutes, two distribution expressed the expresses separation (or boiling between forces two these variables in that gives distillation

Activity There is and solute thermodynamics Raoult’s a X, often proportionality for concept the between measure Equation distribution gas the and Consider as volumes yields: 1 @ this pressures molecular that important coefficients with

66 above where GC a allow the Thus a the Ris phase, their tion Since that reason pared