Ferric chloride hexahydrate (FeCl3·6H2O) and benzene-1,3,5-tricarboxylic acid (H3BTC) were purchased from Sigma Aldrich (St. Louis, MO, US). Ferrous chloride tetrahydrate (FeCl2·4H2O) was obtained from Xi Long Chemical Co., Ltd. (Guangdong, China). Methylacrylic acid (MAA), tetraethyl orthosilicate (TEOS), and thiophene were supplied by Aladdin Industrial Corporation (Shanghai, China). Ammonia solution (25%, w/w) was purchased from Macklin Biochemical Co., Ltd. (Shanghai, China). Analytical grade ethanol and trichloromethane were provided by Beijing Chemical Works (Beijing, China). LC grade acetonitrile (ACN) and hexane were acquired from Fisher Scientific (Pittsburgh, USA). DMP (99.5% purity), DEP (99.5% purity), DBP (99.4% purity), BBP (98.4% purity), DEHP (99.6% purity), and DnOP (99.5% purity) were supplied by Dr Ehrenstorfer GmbH (Augsburg, Germany).
The standard stock solutions (1.0 mg mL−1) of the tested PAEs were prepared by reconstituting the appropriate amount of each tested analyte in ACN and stored at 4 °C in dark. Working solutions were prepared daily by appropriate dilution with ACN. To minimize the risk of xenobiotic phthalate contamination, all solvents were examined for the presence of phthalates before use.
The standard stock solutions (1.0 mg mL−1) of the tested PAEs were prepared by reconstituting the appropriate amount of each tested analyte in ACN and stored at 4 °C in dark. Working solutions were prepared daily by appropriate dilution with ACN. To minimize the risk of xenobiotic phthalate contamination, all solvents were examined for the presence of phthalates before use.