GC Determination of 2,4-Dichloro-6-nitrophenol and Pentachlorophenol in Fishpond Water

Two residual herbicides, i.e., 2,4-dichloro-6-nitrophenol and pentachlorophenol, in sample of fishpond water were enriched by SPE on GDX201 column, and eluted with methylene chloride. The eluate obtained was then derivatized with N-(tert-butyldimethylsilyl)-N-methyl-trifluoroacetamide, and the derivatized products in ethyl acetate were determined by GC, from which contents of the 2 herbicides were obtained. Linear relationships between values of peak area and mass concentration of 2,4-dichloro-6-nitrophenol and pentachlorophenol were obtained in the same range of 10-200 μg·L-1, with limits of detection (3S/N) of 0.09 μg·L-1 and 0.16 μg·L-1 respectively. Tests for recovery and precision were made by standard addition method using fishpond water as matrix, giving values of average recovery of 98.3% for 2,4-dichloro-6-nitrophenol, and 98.6% for pentachlorophenol with RSD′s (n=5) of 3.6% and 4.3% respectively.