Determination of bisphenol A in Iranian packaged milk by solid-phase extraction and HPLC

A solid-phase extraction (SPE) method for sample cleanup and preconcentration of bisphenol A in Iranian milk packages and its determination by HPLC-UV is presented. Optimum conditions for SPE were 10 cm(3) water/methanol (80: 20, v/v) at pH 7 as washing solvent and 4 cm(3) methanol for elution, providing good cleanup and high recovery (>97%) for the analyte. Maximum loading capacity and breakthrough volume for the SPE were 600 mu g and 750 cm(3) of 5 ng/ml for bisphenol A, respectively. The best mobile phase used for HPLC was water/methanol (30: 70, v/v) at pH 6.5 (adjusted with phosphate buffer) at 25 degrees C. The limit of detection, linear range, and repeatability of retention time and peak height were 0.039, 0.50-50.0 mu g/cm(3) (r(2) > 0.99), 3.2, and 2.4%, respectively. Recoveries of bisphenol A ranged between 97 and 102%. Precision of the overall analytical procedure was estimated by five replicate measurements for bisphenol A in milk samples and ranged from 0.472 to 1.014 mg/dm(3).