Determination of 2,6-diisopropylnaphthalene (DIPN) and n-dibutylphthalate (DBP) in food and paper packaging materials from US marketplaces

A gas chromatography-ion-trap tandem mass spectrometry procedure was developed for the determination of 2,6-diisopropylnaphthalene (DIPN) and n-dibutylphthalate (DBP) in domestic and imported paper packages and food sold in US marketplaces. The procedure involved ultrasonic extraction with dichloromethane, followed by analysis with the gas chromatography-ion-trap tandem mass spectrometry. Calibration curves for DIPN and DBP were achieved with concentrations ranging from 0.01 to 10 g ml-1 and the corresponding r2 values were 0.9976 and 0.9956, respectively. In most of the fortified samples the recoveries were higher than 80% with a relative standard deviation (RSD) 10%. Using this procedure, it was found that less than 20% of the tested domestic packages and more than 60% of the tested imported food packages contained both DIPN and DBP. The concentrations of DIPN and DBP ranged from 0.09 to 20 mg kg-1 and 0.14 to 55 mg kg-1, respectively, with most of the DINP and DBP levels lower than 20 mg kg-1. DIPN was not detected (0.01 mg kg-1) in 41 food samples and DBP was only detected in two domestic and four imported food samples with concentrations ranging from 0.01 to 0.81 mg kg-1.