Determination of Two Photoinitiator Residues in Toy Coatings by Ultrasonic Extraction-UHPLC-MS/MS

A method for the determination of 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (IHT-PI 910) and 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (IHT-PI 907) in toy coatings by ultrasonic extraction-ultra high performance liquid chromatography mass spectrometry (UHPLC-MS/MS) was established. The sample was extracted with 10 mL acetonitrile at 60 ℃ for 30 min, then mixed with 0.1% (volume fraction, the same below) formic acid solution and filtered through 0.20 μm membrane. The filtrate obtained was analyzed by UHPLC-MS/MS. ACQUITY UPLC BEH C₁₈ chromatographic column was used as stationary phase, and mixed solution composed of acetonitrile and 0.1% formic acid solution with various volume ratios was used as mobile phase for gradient elution. The targets separated were analyzed with electrospray ion source positive ion (ESI⁺) mode and multiple reaction monitoring (MRM) mode. The results showed that under the optimized test conditions, the two photoinitiators could be determined within 3.00 min; linear ranges of the standard curves of 2 targets found were both 0.5-100 μg·L^-1, with detection limits (3S/N) of 1.0 μg·L^-1; the spiked recovery was made on the negative samples at 3 concentration levels, giving values of recovery ranged from 87.9% to 93.4%, and RSDs (n=7) of determined values were in the range of 1.2%-8.6%. This method was used in the analysis of 20 samples, and photoinitiators were detected in 3 samples, with the maximum detection amount of 1 528 mg·kg^-1 for IHT-PI 907 in No.2 sample, exceeding the limit (1 000 mg·kg^-1) specified by REACH regulation.