Membrane Protected Micro-Solid Phase Extraction of Pharmaceuticals from Environmental Water Samples

Abstract

Membrane-assisted, micro solid phase extraction (?-SPE) of selected pharmaceuticals, was examined in this work, for insights into sorbent designs and selection criteria that could enhance key parameters of ?-SPE namely; enrichment factors and relative recovery, beyond what can be achieved using octadecyl silica gel sorbents. Zwitterated silica gel sorbents (ZIPS) were found promising, as both high relative recoveries and enrichment factors could be realized ZIPS-based ?-SPE. The recently reported, repellant nature of zwitterated silica surfaces towards random sorption of surface-active, oligomeric and polymeric species, was suggested as a possible reason for the observed improvement in ?-SPE performance. It is conceivable, that humic and fulvic acids which are also oligomeric, surface-active substances would compete less effectively with analytes for such surfaces. This possibly leads to both high enrichment factors and relative recoveries during ?-SPE. Such sorbents are therefore, promising platforms for assembling sorbents for solid phase extractions of environmental water samples.