The stationary phase capacity concept in elution liquid chromatography

✍ Scribed by Gareli, P. ;Semerdjian, L. ;Caude, M. ;Rosset, R.

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 729 KB
• Volume: 7
• Category: Article
• ISSN: 0935-6304
• DOI: 10.1002/jhrc.1240070304

✦ Synopsis

The stationary-phase capacity concepts derived from linear capacity are discussed in connection with the needs of analytical, trace enrichment analysis and preparative chromatography and shown to be unsuited to them. A new concept based on stationary-phase saturation and called "available capacity" is proposed. It generalizes the ion-exchanger exchange capacity to adsorption and partition chromatography when the sampling solvent is the mobile phase.

In linear elution chromatography the available capacity is proportional to the solute concentration Co and to the analytical capacity factor k' ; for given C , and k' values, it is independent of the nature of the solute. Furthermore, when both the concentrations and the analytical capacityfactors (practically,forC,a 1 M and k' 2 10, respectively) are high, the available capacity reaches a value roughly independent of C , and k', called "maximum available capacity" and related only to the number of sites available on the stationary phase. Numerous measurements were made in ion-exchange, adsorption, and reversedphase chromatography. For solutes having a single polar functional group interacting with the stationary phase, the orders of magnitude of the maximum available capacity are 1.2 mmole 9-l for a classical silica gel (Partisil5 pm, 400 m-2 g-' with a water content of 2.7%); 1.8 mmole 9-l for the Lichroprep RP 8 octyl bonded silica (1 1.6'10 carbon content); 3.8 mmole g-' for an anion exchanger resin of Dowex type.