a new ultrasonic thermostatic-assisted cloud point extraction/spectrophotometric method for the preconcentration and determination of bisphenol a in food, milk, and water samples in contact with plastic products

Bisphenol a (bpa) contamination in foods and beverages usually occurs as a result of migration from the packages that contain it. in this context, a simple, easy-to-use, and efficient method was developed for the spectrophotometric determination of bpa in food, milk, and water samples in contact with plastic products after preconcentration by ultrasonic-thermostatic-assisted cloud point extraction (uta-cpe). the method is based on the charge transfer-sensitive complexation of bpa with 3-methylamino-7-dimethylaminophenothiazin-5-ium chloride (azb) in the presence of cetyltrimethylammonium bromide (ctab) at ph 8.5 and then extraction of the formed complex into the micellar phase of polyethylene glycol dodecyl ether (brij 35). the effects of the analytical variables affecting complex formation and extraction efficiency were systematically studied and optimized. under optimized conditions, a good linear relationship was obtained in the range of 1.2–160 μg l−1 with a detection limit of 0.35 μg l−1. after preconcentration of a sample of 20 ml, a sensitivity enhancement factor was found to be 180. the accuracy and reliability of the method were evaluated by recovery studies from the spiked quality control samples and intraday and interday precision studies. from the studies conducted, the extraction efficiency (e%) was in the range of 94–103% with a relative standard deviation lower than 5.2% (as rsd%, n = 5). the method was successfully applied to the preconcentration and determination of bpa from the selected sample matrices.