Abstract: A method for simultaneous determination of nine fluorescent brighteners (FWA52, FWA135, FWA184, FWA185, FWA199, FWA367, FWA368, FWA378 and FWA393) in plastic food contact materials was developed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were extracted ultrasonically and sequentially with trichloromethane and methanol at room temperature for 30 minutes either, and the combined extract was blown to near dry by nitrogen and redissolved in methanol. For chromatographic separation, gradient elution was performed with ammonium acetate solution-acetonitrile as the mobile phase. Detection was performed using an electrospray ionization source in the positive ion (ESI+) model with multiple reaction monitoring (MRM), and quantification by external standard method. The results showed that the calibration curves for the nine fluorescent brighteners were linear in the range of 0.5–1 000 ng/mL with correlation coefficients greater than 0.999. The limit of detection (LOD) was 0.05–3.2 μg/kg, the limit of quantitative (LOQ) was 0.2–10 μg/kg, and the recoveries for spiked samples ranged from 76.11% to 106.55%, with relative standard deviations (RSDs, n = 6) of 1.97%–8.31%. The method proved to be simple, accurate, and sensitive, and had good recovery and repeatability. It could suitable for the determination of fluorescent whitening agents in plastic contact products.

Key words: ultra-high performance liquid chromatography-tandem mass spectrometry; plastic; food contact materials; fluorescent whitening agents