SOLID-PHASE EXTRACTION OF AMINOBENZOIC ACIDS AND AMINOTOLUENESULFONICACIDS WITH GRAPHITIZED CARBON-BLACK

The extraction of amphoteric aromatic amines from water samples is dif ficult because of their high polarity. For the enrichment of aminobenz oic acids and aminotoluenesulfonic acids with solid-phase extraction, graphitized carbon black (GCB) was investigated. With few exceptions, the 12 analytes studied were extracted with recoveries > 60% at neutra l or basic pH, whereas at pH 3 low recoveries were obtained. Addition of salt caused a decrease of about 50% in recoveries, addition of stan dard humic acid a decrease of about 20%. The capacity of GCB cartridge s was determined with the breakthrough volume for 4-aminobenzoic acid at different concentrations to be 0.5-1% (w/w).