Critical reconsideration of the physical meaning and the use of fundamental retention parameters in gas chromatography. New IUPAC recommendations

The term "corrected retention volume" V-R(o) was introduced by Martin and James in 1952 and is the most important retention parameter in gas chromatography Its calculation involves multiplication of the measured volume with the "compressibility correction factor" j = 3/2. (p(i)/p(o))(2)-1 /(p(i)/p(o))(3)-1. Followers misinterpreted the James and Martin statement that the finally obtained "V-R(o) is the limiting value of V-R as p(i)/p(o) tends to unity" and introduced an additional recalculation of the corrected retention volume to standard conditions, 273 K and p = 1 atm. The use of standard conditions has resulted in publication of a great deal of distorted thermodynamic data, and has largely resulted in the cessation of the use of GC to collect such data. Examples of distortions of thermodynamic data are given to demonstrate the need for not using, standard" conditions. The distortion imposed by correction to standard conditions has had almost no impact on the explosive growth of GC as an analytical technique, but has limited its use for more fundamental physical measurements. The physical meaning of the j(3)(2) factor is the ratio of the gas pressure at the column outlet to the pressure in the column averaged over the column length j(3)(2) = p(o)/(p) over bar. This unambiguously defines the corrected retention volume as the analyte retention volume measured at the column outlet and then recalculated to the column temperature and averaged column pressure: V-R(o) = V-R,V-a(T-c/T-o)j(3)(2) = V-R(T-c/T-o)(p(o)/(p) over bar). New lUPAC Recommendations in 2001 formulated thermodynamically sound definitions for the most fundamental retention parameters in GC. This paper is an attempt to clarify the situation.