Determination of endocrine-disrupting compounds in cereals by pressurized liquid extraction and liquid chromatography-mass spectrometry. Study of background contamination

A sensitive method based on pressurized liquid extraction (PLE) and liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) has been developed for the determination in cereal samples of seven endocrine-disrupting compounds: bisphenol A (BPA), 4-tert-butylbenzoic acid (BBA), 4-nonylphenol (NP), 4-tert-butylphenol (t-BP), 2,4-dichlorophenol (DCP), 2,4,5-trichlorophenol (TCP) and pentachlorophenol (PCP). For the PLE procedure, methanol was selected as the extraction solvent. An experimental design approach was applied to optimize other PLE parameters. The recoveries achieved for the all seven compounds were in the 81-104% range, with relative standard deviations of 4-9%. An additional preconcentration step, based on solid-phase extraction (SPE), after the PLE step proved to be a successful way for obtaining a more sensitive method. The detection limits achieved in corn breakfast cereals were in the 0.003-0.013 microg g(-1) range, except for BPA, with a detection limit of 0.043 microg g(-1), for a sample size of 2.5 g. These values are similar to or even lower than currently legislated limits for pesticides in cereals and cereal-based foodstuffs. We also investigated possible contamination during the experimental process by the target compounds released from purified water, plastics, syringes, peristaltic pump tubes, glassware and other laboratory materials in contact with the samples along the analytical process.