GAS-CHROMATOGRAPHIC ANALYSIS OF TRACE PHENOLS BY DIRECT ACETYLATION IN AQUEOUS-SOLUTION

Acetate esters of six phenolics were formed by the direct addition of 500 μl acetic anydride to 250 ml of a dilute aqueous phenolic solution containing 10 g sodium bicarbonate. In the concentration range of 0.08-0.24 μmoles/1, phenol, o-cresol, m-cresol, p-cresol, 2,4-dichlorophenol and 1-naphthol easily formed acetate esters which provided for improved gas chromatographic characteristics and virtually quantitative recovery from aqueous solution. On extraction with small volumes of methylene chloride, phenol could only be recovered to the extent of 28-41% in the 0.2-2.0 mg/1 range. On the other hand, phenyl acetate, formed in water prior to extraction, was 100% recovered. The stable acetate esters can be analyzed using standard gas chromatographic solumns such as OV-17 or OV-101 while phenolics generally require specially deactivated packings. On 1% SP-1240 DA all of the derivatives, with the exception of m- and p-cresyl acetate, could be separated. © 1979.