In situ derivatization combined to automated microextraction by packed sorbents for the determination of chlorophenols in soil samples by gas chromatography mass spectrometry

• Combination of in situ derivatization MEPS-GC-MS for automated soil analysis.
• MEPS and QuEChERS procedures are compared as extraction techniques of the derivatizated analytes.
• The proposed methodology is simpler and consumes less volume of organic reagent to the traditional solvent extraction processes.
• Validation of the methodology with a Certified Reference Material.
• The detection limits of the proposed procedure are lower than 1 μg kg−1 in soil.

A method based on the coupling of in situ extraction and derivatization of chlorophenols (CPs) (2-chlorophenol, 4-chloro-3-methylphenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) from soils, accomplishing their preconcentration by means of automated microextraction by packed sorbent (MEPS), is proposed. After extraction and acylation of the chlorophenols in aqueous medium, the liquid phase obtained is subjected to the MEPS procedure. The QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) and MEPS techniques were compared and the results confirmed the preconcentration carried out with MEPS.The existence of a matrix effect was checked and the analytical characteristics of the method were determined in a soil sample. The method provided good linearity (from 1 to 12 μg kg−1), together with good repeatability and reproducibility values (RSD equal to or less than 10%). The limits of detection were in the 0.118–0.894 μg kg−1 range. A certified reference material was applied to validate the proposed methodology.