EVALUATION OF THE GOULDEN LARGE-SAMPLE EXTRACTOR FOR ACIDIC COMPOUNDSIN NATURAL-WATERS

The Goulden Large-Sample Extractor has received extensive use for moni toring;and surveillance surveys of natural waters impacted by pulp and paper mills and agricultural runoff water. However, there are concern s about whether this sampler, which was originally developed for extra ctions of hydrophobic polycyclic aromatic hydrocarbons, polychlorinate d biphenyls, and other organochlorines, is suitable for sampling polar acidic compounds. The sampler was evaluated for recovery of surrogate s for resin acids, fatty acids, herbicide acids, and chlorophenols fro m natural waters. Performance tests conducted in this work indicated t hat three surrogate compounds with K-p (C-DCM/C-water pH 2) values fro m 16,700 to 1,260 were extracted from pH 2-adjusted 20-L water samples with an average recovery of 83.6%. The surrogate compounds with K-p v alues less than 1,000 were extracted with significantly lower recoveri es. The variability ranged from 10 to 36% relative standard deviation. Recoveries and variability compared favorably with reported recoverie s and variabilities for neutral pesticide surrogates. Specific perform ance criteria (percent recoveries +/- standard deviation, number of de terminations in parentheses) observed for the surrogates 2,4,6-tribrom ophenol, heptadecanoic acid, O-methylpodocarpic acid, dichlorophenylac etic acid, and 4-bromophenol were 89.5 +/- 24.0 (17), 82.8 +/- 21.7 (1 8), 78.4 +/- 14.8 (18), 41.9 +/- 8.5 (16), and 22.1 +/- 8.1 (19), resp ectively. Low recoveries of the 4-bromophenol surrogate may be due in part to side reactions with diazomethane. As a result, 4-bromophenol i s not recommended as a surrogate. These values can be used to provide guidelines for acceptable surrogate recoveries and validation of extra ctions of polar acidic compounds.