Quantitative determinations of seven fluorescent whitening agents in polystyrene and polyvinyl chloride plastics by ultrahigh performance liquid chromatography-tandem mass spectrometry

A simple, fast and sensitive protocol was developed for the simultaneous determinations of seven fluorescent whitening agents (FWAs) in polystyrene (PS) and polyvinyl chloride (PVC) plastics involved in food packaging, using ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with positive electrospray ionization and multiple reaction monitoring mode. Sample preparation included dissolution, extraction, and methanol-induced polymer precipitation. All analytes were eluted within 6 min using methanol. The calibration curves were drawn in the range of 0.1-50 mu g L-1 for the seven FWAs, with good correlation coefficients (R-2 > 0.995). The detection limits were 0.7-9 mu g kg(-1), and the quantitation limits were 2.5-30 mu g kg(-1). Recoveries ranged from 81.4% to 116%, with a relative standard deviation (RSD) of 2.9-10.8% (n = 6). Intra- and inter-day precisions (n = 6) were lower than 15%. The UPLC-MS/MS protocol developed in this work was confirmed to be a fast, precise and quantitative technique for the simultaneous determinations of FWAs in PS and PVC plastics.