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Solute Retention in Column Liquid Chromatography: IX. Comparison of Methods of Determination of the Void Volume in Liquid-Liquid Chromatography

1987; Marcel Dekker; Volume: 10; Issue: 8-9 Linguagem: Inglês

10.1080/01483918708066797

2331-0413

R. A. Djerki, R. J. Laub,

Microfluidic and Capillary Electrophoresis Applications

Abstract It is shown in the case of true liquid-liquid chromatography (LLC) (OV-1 polysiloxane stationary phase; methanol, water, or blended mobile phases) that no one method of determination of the column void volume gives unambiguous results. A generalized convention regarding definition of the column and system void volumes is therefore developed. It is stipulated that, barring multiple retention mechanisms, the former, VM' is comprised of the space within a column to which solutes have access, yet which is not otherwise occupied by the stationary phase, the packing matrix, or immobilized carrier. VM should thereby be no greater than the retention volume of any solute; and should also be invariant with mobile-phase composition as well as with temperature. The method of self-consistent fitting of the retentions of homologous series of alcohol solutes as a function of homolog number is said overall to provide the column void volume that most closely satisfies these criteria, although several other techniques give results that agree to within close to experimental error with this value. An altemative thermudynamio-based convention wherein the VM that yields an activity coefficient of unity for the mobile phase, irrespective of its composition, is also said to heve merit.