A comprehensive analytical method was developed for the determination of six allergenic coumarin compounds (coumarin, 7-methyl coumarin, 7-methoxycoumarin, 7-ethoxy-4-methyl coumarin, 4,6-dimethyl-8-tert-butyl coumarin and hexahydrocoumarin) in children's toys based on hollow-fiber liquid-phase microextraction (HF-LPME) followed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). HF-LPME was employed in sample pretreatment with the following parameters:extraction solvent of n-octanol, stirring rate of 700 r/min, extraction time of 50 min and amount of sodium chloride of 0.7 g. After chromatographic separation on an ACQUITY UPLC BEH Phenyl column (150 mm×2.1 mm, 1.7 μm), the target compounds were analyzed under multiple reaction monitoring (MRM) mode in positive electrospray ionization mode. The limits of quantification (LOQs) of the six allergenic coumarin compounds were either 2 μg/kg (7-ethoxy-4-methyl coumarin and 4,6-dimethyl-8-tert-butyl coumarin) or 10 μg/kg (coumarin, hexahydrocoumarin, 7-methyl coumarin and 7-methoxycoumarin). The average recoveries at different spiked levels ranged from 70.8% to 118.9% with relative standard deviations (RSDs) of 0.19%-16.34% (n=6). The proposed method is accurate, sensitive, reliable, and can be applied for the inspection and quality control of toy products.
Keywords: allergenic coumarin compounds; children's toys; hollow-fiber membrane; liquid-phase microextraction (LPME); ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).