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

Abstract

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 µg ml⁻¹ and the corresponding r ² 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.

Keywords:

• gas chromatography-ion-trap tandem mass spectrometry (GC-IT-MS/MS)
• 2,6-diisopropylnaphthalene (DIPN)
• n-dibutylphthalate (DBP)
• paper food package
• dry foods

Acknowledgement

The authors thank Dr Jon W. Wong and Dr Gregory W. Diachenko for revising the manuscript.