Twelve canned food items of six different brands, including two green beans, two Harris Teeters brand’s noodle soups, two Food Lion brand’s noodle soups, two canned sausages, two canned pastas, and two BPA-free products will be purchased from local grocery stores. For each of the brand, the newest and oldest expiration dates found on the market will be selected.
Sample preparation:
The liquid and solid parts of each can will be separated by sieving. The residues on the can’s wall will be washed with distilled water and added to the liquid portion.
-The solid part will be homogenized. Five grams of that homogenate with 5ml of Acetonitrile and 5ml of hexane will be mixed by vortexting for one minute and then centrifuged for 20 minutes at 2500xg. Several additions of 5ml of ACN- will be used to extract BPA from the solid and the hexane phase in the centrifuge tube. HPLC grade will be used to analyze BPA in the extract. A mobile phase of 20ul ACN-/water (60v/40v) will be injected into the chromatography column at a flow rate of 1ml/min at 25C and analyzed in isocratic elution; the detection wavelengths will be 275nm and 315nm. BPA standard working solution will be prepared by diluting the analyte with the mobile phase solution. Ten microliters of the working solution will be injected into HPLC grade to obtain a calibration curve of concentration vs. peaks of BPA.
-An aliquot of 5 ml of the liquid portion will be diluted with 5ml of the above mobile phase solution. It will be then mixed by shaking with 5ml ACN- and 15ml polyprolene in a centrifuge tube for one minute. After centrifuging at 2500xg for 10 minutes, the supernatant will be discarded, and the solid will be extracted with 5ml of ACN- solution. The residue was then filtered and dried with nitrogen gas at 40C before dissolving in 200ul of the mobile phase solution. Ten microliters of the analyte will be injected into HPLC
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