Determination of the Migration Amount of 1,4-Diphenyl-1,3-Butadiene, a Fluorescent Whitening Agent, in Oil Foodstuffs by Solvent Extraction-HPLC

Eight kinds of oily foodstuffs were chosen as samples for study and were pounded and homogenized separately. (5.00±0.01) g of the sample were taken and extracted twice with acetonitrile (10.0 mL for each extraction) for 3 min under shaking. After centrifuging, 1.0 mL ofthe supernatant was taken, and the 2 supernatants were combined, to which 1.3 mL of water was added, and the solution was filtered through 0.45 μm fitering membrane. The filtrate was used for HPLC analysis. Agilent Eclipse XDB-C₈ column was used as a stationary phase, and mixed solvents of (A) water and (B) acetonitrile with various ratios were used as mobile phases in the gradient elution. Data of peak area of 1,4-diphenyl-1,3-butadiene (DPBD) were measured by DAD at 330 nm and retention time of 13.01 min. Linear relationship was found between values of mass concentration of DPBD in the range of 0.01-50.0 mg·L^-1 and the corresponding peak areas; with detection limit (3s) of 0.01 mg·kg^-1. Using the blank samples of the 8 selected foodstuffs as matrixes, test for precision and recovery by adding standard DPBD solution at 3 concentration levels were made, giving results of recovery in the range from 80.1%-119%, and RSDs (n=6) ranged from 1.8%-12%. Eigh PE bags with same specification and containing same amounts of DPBD (12.58 mg·kg^-1) were taken and the 8 foodstuffs (5.00 g each) were added separately into the PE bags. Then the bags were sealed up under vacuum, and tested for the migration of DPBD from the PE bags to the foodstuffs according to the method described in GB 31604.1-2015, with DPBD determined by HPLC as described above. It was found that the DPBD was easier to migrate into the fried foodstuffs with high oil or fat-contents on their surfaces. As tested under different migration conditions of temperature and time, amounts of DPBD found in 3 fried foodstuffs were ranged from 0.17-0.47 mg·kg^-1; while no migrations of DPBD were found in the 5 remainder foodstuffs.