Abstract: The presence of isothiazolinones in toys is severely restricted in European Toy Safety Directive because of their allergenicity. A rapid analytical method for the determination of isothiazolinones (2-Methyl-4-isothiazolin-3-one, 5-Chloro-2-methyl-4-isothiazolin-3-one and 1,2-Benzylisothiazolin-3-one) in toys by liquid chromatography-tandem mass spectrometry has been developed. After ultrasonic extraction in water, samples were analyzed by LC-MS/MS. Methanol:water(15:85, V/V) isocratic elution was used as mobile phase. The linear ranges of calibration curves were 2.0 μg/L ~1 000 μg/L, and the limits of quantification for this method were 0.04 mg/kg for all the analytes employing selected-reaction monitoring (SRM) mass spectrometry. While for the recommended method in EN71-11:2005, the limit of quantification for 1,2-Benzylisothiazolin-3-one was 5 mg/kg, indicating that the sensitivity of this method was beyond that of the recommended method. The recoveries for two types of standard spiked samples were in the range of 95.9%~105.2% and 94.7%~102.8%, respectively, and the relative standard deviations ranged from 3.04% to 4.96% and 2.36% to 4.79%, respectively. The method was applied to ten toy samples, and the precision and sensitivity could meet the requirements of the determinations of isothiazolinones in toys in EN71-9:2005.

Key words: isothiazolinones, preservatives, toys, liquid chromatography-tandem mass spectrometry (LC-MS/MS)