Determination of the migration of isosorbide in isosorbide modified polyethylene terephthalate products by gas chromatography
Objective To establish a method for the determination of migration of isosorbide in isosorbide modified polyethylene terephthalate(PET)products by gas chromatography-flame ionization detector(GC-FID).Methods The effects of different chromatographic conditions on the separation of isosorbide were investigated.HP-5 was selected as the separation column and 260℃was selected as the injection port temperature.The effects of different pretreatment methods on the extraction of isosorbide from food simulants were investigated.The olive oil food simulant was extracted with methanol,purified with n-hexane and filtered before analyzed.The 95%ethanol and isooctane simulants were directly analyzed by the machine after filtered.Other food simulants were diluted with methanol and then directly analyzed by the machine.The external standard method was used for quantification.Results Isosorbide had a good linear relationship in the range of 2.5-40.0 mg/L(aqueous food simulants),0.6-10.0 mg/L(substitute simulants)and 1.5-25.0 mg/kg(fatty food simulants),and the correlation coefficient was above 0.995.The limit of detection of this method for the migration of isosorbide was 0.8 mg/kg(aqueous food simulants),0.2 mg/kg(substitute simulants)and 0.5 mg/kg(fatty food simulants).The limit of quantification was 2.5 mg/kg(aqueous food simulants),0.6 mg/kg(substitute simulants)and 1.5 mg/kg(fatty food simulants).The spiked recoveries were 92.0%-112.3%,and the relative standard deviation was 0.2%-4.3%(n=6).Conclusions This method has good linearity,high precision,sensitivity and accuracy,and can meet the detection requirements of isosorbide migration in modified PET products.