The influence of properties of packing materials upon the recovery of biological substances isolated from urine by solid-phase extraction.

A series of packing materials with alkyl phase chemically bonded to silica gels of various porosity have been prepared. These packings have been used to isolate the test substances 5-hydroxyindole-3-acetic acid (5-HIAA) and serotonin (5-HT) from urine. The influence of the support porosity, structure of chemically bonded phase, length of alkyl chain, and coverage density on the recovery of isolated substances was studied.