Bpa standard

The BPA standard (minimum purity of 99%) was purchased from Sigma-Aldrich. Methanol (for HPLC), acetonitrile (for HPLC), and water (for HPLC) were provided by Carlo Erba. The SPE cartridges (Chro-mabond C18, Macherey-Nagel) were purchased from Delchimica. Stock BPA solution (0.1 mg/mL) in acetonitrile was stored at -20°C for not more than 6 mo. A Jasco HPLC apparatus equipped with a Jasco quaternary pump 2089 plus, combined with a fluorescence detector 821-Fp (Jasco) and a Synergy column 4-µm Fusion-RP 80 Å (250 × 4.60 mm i.d.; Phenomenex) were used for the analyses. For milk packaging, a gabletop carton (Pure-Pak) was used. The packaging materials consisted of a polyethylene coating of fossil origin outside and inside of the milk container, and cardboard as a central material. A low-density polyethylene cap was used to close off the milk carton. The producer declaration ensured that the BPA had not been used in the manufacturing of plastic materials, and BPA migration was not a risk.

A solution of plasticizers containing seven plasticizers (dimethyl phthalate (DMP), di-ethyl phthalate (DEP), di-n-butyl phthalate (DnBP), benzyl butyl phthalate (BBP), di-n-octyl phthalate (DnOP), bis(2-ethylhexyl) phthalate (DEHP) and bis(2-ethylhexyl) adipate (DEHA)) at 1000 mg/L was purchased from Supelco Analytical (Philadelphia, PA, USA). BPA standard was procured from Sigma Aldrich (St. Louis, MO). Labeled standards of 13 C-caffeine, 13 C-DEHP and 13 C-BPA were obtained from Cambridge Isotope Laboratories (Andover, MA, USA). Reference standards of 17 α-estradiol and estriol were purchased from Fisher (St. Louis, MO), while 4-androstenedione, 17 α-hydroxyprogesterone, 17 α-trenbolone, α-zearalanol, α-zearalenol, 17 β-estradiol, 17 β-trenbolone, β-zearalanol, β-zearalenol, androstenedienedione, androsterone, epitestosterone, estrone, ethynylestradiol, melengesterolacetate, progesterone, testolactone and testosterone were purchased from Sigma-Aldrich (St. Louis, MO). Working standard solutions for calibration and recovery spikes were prepared from the stock standard solutions and stored at -20 °C.