SAMPLING CHARACTERISTICS OF OCTADECYLSILOXANE-BONDED SILICA PARTICLE-EMBEDDED GLASS-FIBER DISKS FOR SOLID-PHASE EXTRACTION

Forced flow planar chromatography was used to characterize the physica l and retention properties of an octadecylsiloxane-bonded particle-emb edded glass fiber medium used for solid-phase extraction. The carbon l oading, intraparticle porosity, binding capacity, and hydrophobicity i ndex indicate that the medium has a large volume of bonded phase essen tially filling the pore volume. The interparticle porosity and specifi c permeability indicate favorable flow characteristics. The flow resis tance parameter and the diameter of the largest pore by the bubble met hod are consistent with a macroscopic homogeneous medium structure fre e of holes and channels. The silanophilic index indicates a significan t concentration of accessible silanol groups and:or other strong hydro gen-bond acid sites. A comparison of retention characteristics to a co mmon cartridge sorbent using the solvation parameter model indicated t hat the cartridge sorbent had a more favorable cavity term for retenti on but the particle-embedded glass fiber medium was more competitive w ith the sample solvent, water-methanol (99:1), for the retention of po lar compounds with significant dipole-type interactions and those beha ving as hydrogen-bond bases. The physical and retention properties of the particle-embedded glass fiber medium confirm irs suitability for u se in solid-phase extraction.