Determination of priority phenolic compounds in soil samples by various extraction methods followed by liquid chromatography–atmospheric pressure chemical ionisation mass spectrometry

Abstract An analytical protocol for the determination of priority phenolic compounds: phenol, 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, pentachlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 4-methylphenol and 2,4-dimethylphenol, in soil samples, is presented. The method uses Soxhlet extraction with methanol–water (4:1) both containing 2% triethylamine. Recoveries varied in the range from 67 to 97% with a standard deviation between 8 and 14%. Additional extraction methods of phenols from soil samples include the use of the microwave-assisted extraction procedure. Results demonstrated that most of these compounds can be recovered in good yields (>70%) from the matrix investigated, except nitrophenols that suffer degradation. Detection limits varied within a range from 20 ng/g for 2,4-dimethylphenol to 100 ng/g for pentachlorophenol, were obtained when using LC–UV. However these values were greatly improved when using LC–APCI-MS in negative ion mode. Validation of the method by analysing a reference soil sample from the BCR program containing eight polycyclic aromatic hydrocarbons and pentachlorophenol, and the analysis of a real environmental soil sample containing pentachlorophenol are also reported.