Gas chromatographic determination of three chlorophenols in toilet paper by ultrasonic assisted extraction and synchronous derivative dispersive liquid–liquid microextraction

Abstract

A simple and sensitive method for the analysis of three chlorophenols (CPs) in toilet paper has been developed for the first time. Acetone was used as a solvent to extract the three CPs from toilet paper assisted by ultrasound irradiation. When the extraction process was finished, 0.5 mL acetone extract was subjected to synchronous derivative dispersive liquid–liquid microextraction (DLLME). During this process, the analytes were rapidly transferred from the acetone extract to another extraction solvent (chlorobenzene) for further clean-up and enrichment. Acetone could also act as a dispersant during the DLLME process, which combined the advantages of ultrasonic assisted extraction and DLLME appropriately. Different factors affecting the extraction efficiency and derivatization step were carefully optimized. Under optimal conditions, the limits of detection for 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol were 1.5 μg kg⁻¹, 0.75 μg kg⁻¹, 0.25 μg kg⁻¹, respectively. Satisfactory linear ranges were observed from 5–500 μg kg⁻¹, 2.5–250 μg kg⁻¹, 1–20 μg kg⁻¹, respectively. Recoveries of three CPs in toilet paper were in the range 70.9–118%. The optimized method was successfully applied to three different toilet paper samples, and pentachlorophenol has been detected in one of the tested toilet papers at a concentration level of 1.2 μg kg⁻¹.