Determination of Migration of 1,1'-Sulfonylbis(4-Chlorobenzene) and 4,4'-Dihydroxybiphenyl in Food Contact Material Products by Ultra-High Performance Liquid Chromatography

Referring to GB 5009.156-2016 and GB 31604.1-2015, food simulants including water, 4% (volume fraction) acetic acid solution, 10% (volume fraction) ethanol solution, 20% (volume fraction) ethanol solution, 50% (volume fraction) ethanol solution, 95% (volume fraction, the same below) ethanol solution and isooctane were used to immerse water cups, milk bottles, threaded ports and coating cans with polystyrene sulfone material. The soak solution of the first 5 food simulants was directly passed through a 0.22 μm filter membrane, and the filtrate was analyzed by ultra-high performance liquid chromatography (UHPLC). An aliquot (10 mL) of 95% ethanol solution or isooctane soak solution was taken, and evaporated to near dryness by rotating at 50℃ and 5 000 Pa. The residue was dissolved and diluted to 10 mL by 70% (volume fraction) methanol solution, and the solution obtained was passed through a 0.22 μm filter membrane. The filtrate was analyzed using UHPLC. The ACQUITY UPLC BEH C₁₈ chromatographic column was used as the stationary phase, and mixed solutions composed of methanol and water at different volume ratios were used as the mobile phase for gradient elution. The detection was performed at a detection wavelength of 247 nm. It was shown that the 2 targets in the 7 food simulants could be completely separated within 6.500 min, and linear relationships between values of the mass concentration of 1,1'-sulfonylbis(4-chlorobenzene) and 4,4'-dihydroxybiphenyl and the peak area were kept in the ranges of 0.03-0.40 mg·L^-1 and 0.3-4.0 mg·L^-1, with lower limits of determination (10S/N) in the range of 0.015-0.030 mg·kg^-1 and 0.023-0.030 mg·kg^-1, respectively. Test for recovery was made at the 3 concentration levels by standard addition method, giving recoveries in the range of 89.0%-110%, and RSDs (n=6) of the determined values ranged from 1.9% to 6.7%. The proposed method was applied to the analysis of 10 batches of actual samples, and the determined values of the 2 targets were lower than the lower limits of determination, meeting the requirements of specific migration limits of GB 4806.6-2016 and GB 9685-2016.