Evaluation of two new examples of graphitized carbon blacks for use in solid-phase extraction cartridges

The performances of two new examples of graphitized carbon blacks (GCBs), Carbograph 4 and Carbograph 5, filling solid-phase extraction cartridges were evaluated. Compared to an older GCB, Carbograph 1, the two new GCBs exhibited far larger abilities in extracting very polar compounds from both 4 l of drinking water and 1 l of water containing an amount of humic materials equivalent to 20 mg/l dissolved organic content. Like older GCB material, the new examples of GCBs have on their surfaces anion-exchange adsorption sites. However, Carbograph 5 partly failed to isolate acidic species from co-extracted non-acidic species by stepwise elution. Moreover, the surface of this sorbent material is more contaminated than those of both Carbograph I and 4 by sites able to bind irreversibly particular adsorbates. The extraction efficiencies of the two new GCBs were also compared with those of two recently introduced polystyrene-divinylbenzene (PS-DVB)-based materials. Recovery data showed that the carbonaceous materials were abler than PS-DVB ones in isolating very polar compounds from large water volumes, such as phenol, water-soluble pesticides, and low-molecular-mass biointermediates of linear alkylbenzenesulfonate surfactants. The positive features of including Carbograph 4 extraction cartridges in analytical schemes for determining traces of very polar pollutants in natural waters are demonstrated by three practical applications.