ABSTRACT
Resin acids are major sources of fish toxicity in many Canadian softwood pulp mill effluents. Therefore, their accurate detection is an important aspect in the evaluation of the environmental impact of these effluents. Among the various methods used to detect and quantify resin acids, gas chromatography (GC) is usually the method of choice due to its high resolution and accuracy. However, major disadvantages such as tedious sample pretreatment protocols and low sample output reduce the suitability of this method for analyzing large numbers of samples in a short period of time. In this paper, a traditional gas chromatographic method and an immunological method were compared. In the GC method, liquid-liquid extraction was further evaluated using four different solvents (diethyl ether, dichloromethane, methyl t-butyl ether and ethyl acetate) for their extraction efficiency. An enzyme-linked immunosorbent assay (ELISA) based on polyclonal antibodies was developed for detecting dehydroabietic acid (DHA), one of the most abundant resin acids found in softwood pulp mill effluents. The direct ELISA can detect DHA in the range between 10 and 500 μg L−1 with 50% inhibition concentration of 261.6 μg L−1. Both GC and the direct ELISA were used to quantify DHA in a spiked effluent and the results were compared. Since the immunoassay requires no pretreatment, a small volume of sample and results in a larger sample output, this alternative method of resin acid analysis shows promise.
