New methodology for the determination of phthalate esters, bisphenol A, bisphenol A diglycidyl ether, and nonylphenol in commercial whole milk samples

This paper reports a new methodology aimed at determining dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, butylbenzyl phthalate, bis(2-ethylhexyl) phthalate, nonylphenol, bisphenol A, and bisphenol A diglycidyl ether in commercial whole milk. These compounds are used as plastic additives, lacquers, resins, or surfactants and can be found in milk due to contact with plastic materials during food processing and storage. They are all suspected endocrine disrupters or mutagens. A multiresidue method based in solid-phase extraction with C-18 cartridges followed by a cleanup step using disposable cartridges was developed. Detection and quantification were performed by gas chromatography coupled to mass spectrometric (GC-MS) detection using an appropriate surrogate (4-n-nonylphenol) and internal standard (deuterated bis(2-ethylhexyl) phthalate]. Limits of detection were from 0.06 to 0.36 mug/kg and intraday variation from 3 and 27%, with recoveries between 73 and 119%. Five brands of commercial whole milk processed and packed in different ways were analyzed. Ail samples contained target compounds at concentrations between 0.28 and 85.3 mug/kg, and the total concentration ranged between 79.3 and 187.4 mug/kg, the levels being higher in sterilized milks. Nonylphenol, diethyl phthalate, dibutyl phthalate, and bis(2-ethylhexyl) phthalate were the major contributors.