THE CHROMATOGRAPHIC BEHAVIOR OF COATED STATIONARY PHASES WITH DIFFERENT SILICAS

Different silicas coated with poly(methyloctylsiloxane) are compared i n terms of the effect of particle shape, particle diameter, mean pore diameter and specific surface area. For irregular particles, the carbo n contents (% C) coated are essentially identical even though there ar e considerable variations in surface area for the different silica sup ports. Sample retentions (k) increase with increasing surface area whi le efficiences (N/m, naphthalene) increase as the particle diameter de creases. Excellent peak symmetries (As) are obtained with most packing s. Spherical particles, with significantly lower surface areas, have l ower carbon loadings and higher surface coverage but produce columns w ith significantly higher efficiences than the irregular particles havi ng similar particle diameter.