Determination of 6 Phthalate Ester Compounds in Stationery Supplies with Complex Matrix by Improved Gas Chromatography-Mass Spectrometry with Solid Phase Extraction

A method of gas chromatography-mass spectrometry with acetonitrile extraction and solid phase extraction column purification was proposed for the determination of 6 phthalate ester compoundsPAEs, including dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), di (2-ethyl) hexyl phthalate (DEHP), di-iso-nonyl phthalate (DINP), di-n-octyl phthalate (DNOP) and di-n-decyl phthalate (DIDP) in 4 stationery supplies (plastic book covers, book membranes, pen holders, rulers) with complex matrix, and the pretreatment conditions of the method, including extractant (ethyl acetate, dichloromethane, mixed solution of n-hexane and dichloromethane at volume ratio of 1:1, n-hexane, acetone, tetrahydrofuran, toluene, acetonitrile), extraction temperature (0, 20, 30, 40℃), and extraction time (10, 20, 30, 40 min) were optimized. The sample was cut into small pieces with the size of 10 cm×10 cm. An aliquot (0.2 g) was taken and immersed into 5 mL of acetonitrile, and the mixture was shaken for 20 min, and extracted by ultrasound at 40℃ for 30 min. Then 1 mL of the extract was taken and passed through the solid phase extraction column (Si/PSA SPE glass column) activated beforehand. The above column was eluted by 10 mL of acetonitrile, and the eluate was collected, and blown to near dryness by nitrogen. The residue was dissolved by n-hexane, and made its volume up to 1 mL. The resulting solution was analyzed by gas chromatography-mass spectrometry, with external standard method for quantification. When purifying the extract of the other 7 solvents, 5 mL of n-hexane was used for rinsing, and 10 mL of mixed solution composed of n-hexane and ethyl acetate at volume ratio of 2:8. was used for elution. The other steps were the same as those of acetonitrile. The extraction effect of each solvent was evaluated using determined values of PAEs in actual samples and spiked recoveries. It was shown that acetonitrile had stronger adaptability to stationery supplies made of different materials. When ultrasonic extraction was made at 40℃ for 30 min, more PAEs were obtained, and their determined values and recoveries were higher (greater than 70.0%). Linear relationships between values of the mass concentration of the 7 PAEs and the peak area were kept in the ranges of 0.2-10.0 mg·L^-1 (DBP, BBP, DEHP and DNOP) and 2.0-100.0 mg·L^-1 (DINP and DIDP), with detection limits (3S/N) in the range of 0.003-0.05 mg·kg^-1. The spiked recoveries were found in the range of 74.1%-107%, with RSDs (n=6) of the determined values in the range of 1.2%-5.1%. The proposed method was used for the analysis of 12 actual samples, and DNOP, DINP and DIDP were not detected. The total detection amount of DBP, BBP and DEHP did not exceed the limit specified in GB 21027-2020.