Porous stationary phases, comparison with

Due to small particle size, the columns packed with micropellicular stationary phases have low permeability (27) and therefore, can not be operated at very high flow rates due to pressure limitations of commercial HPLC instruments. In comparison to porous particles, the surface area of stationary phases per unit column volume is low, and hence, their loading capacity is correspondingly smaller. This is particularly evident in the isocratic analysis of small molecules where the column can be easily overloaded. Therefore, micropellicular sorbents do not appear to offer advantages in the HPLC of small molecules. 

G. Castello and G. D Amato, Comparison of the polarity of porous polymer-bead stationary phases with that of some liquid phases , /. Chromatogr. 366 51-57 (1986). 

Mathiasson, L. Jonsson, J.A. Olsson, A.M. Haraldson, L. Sensitivity of retention index to variations in column liquid loading and sample size. J. Chromatogr. 1978,152, 11-19. CasteUo, G. D Amato, G. Classification of the "polarity of porous polymer bead stationary phases by comparison with squalane and apolane standard liquid phases. J. Chromatogr. 1983, 269,153 160. 

---