Hydrocarbonaceous surface area

As the carbon load of a particular type of stationary phase increases we expect both the phase ratio and the contact surface area for a given eluite probe to reach a plateau so that the dependence of k or log k on the carbon load is likely to be hyperbolic over a sufficiently wide range. A key point in this treatment is the accessible hydrocarbonaceous surface area, which is difficult to quantify and may strongly depend on the molecular architecture of the eluite used as a probe. Furthermore, the involvement of the... 

Fig. 7.4. The effect of salt concentration on capacity factor, k. Chromatographic conditions column, Partisil 1025 ODS (250 mmx4.6 mm I.D.) mobile phase, the concentration of KCl in a 0.05 M KH2PO4 solution was varied flow rate, 1 ml/min temperature, 25 °C detection, UV at 254 nm. The upper scale shows the surface tension of the eluent. The hydrocarbonaceous surface area (HSA) and the total surface area (TSA) of the solute molecules are shown. Reproduced from Horvath et al. (1976),...

In /c (or In values and the hydrocarbonaceous surface areas of the solutes. For example, the dependence of the activity coefficient, for the phosphorylation of ten myosin-related analogues on the extrathermodynamic functional group effect, t, was assessed [10] according to the linearised expression... 

---