EVALUATION OF GRAPHITIZED CARBON-BLACK AS A SELECTIVE ADSORBENT FOR EXTRACTING ACIDIC ORGANIC-COMPOUNDS FROM WATER

By a simple and rapid treatment, graphitized carbon black (GCB) can be made to act as both a reversed phase and an anion exchanger. The base -neutral/acid fractionation of organic species extracted from water wi th a GCB cartridge can be easily achieved by differential elution, pro vided that the pK(a) values of the acidic species are not higher than about 7. A tetramethylammonium hyroxide-basified solvent mixture is th e most effective eluent for the rapid elution from a GCB extraction ca rtridge of any kind of organic acid. The subfractionation of acidic sp ecies can be easily performed on the basis of their acidity strength b y passing sequentially through a GCB cartridge various solvent mixture s containing suitable phase modifiers. The ability of a GCB extraction cartridge to retain organic acids was unaffected by the ionic strengt h of the water sample. The influence of fulvic acids dissolved in wate r on the capability of GCB to extract acidic compounds and isolate the m from co-extracted base-neutral species was evaluated. The advantage of using a GCB cartridge over that containing a chemically bonded sili ca for accurately determining acidic compounds is demonstrated by two practical applications.