Component Identification of Mineral Oil Hydrocarbons and Additives in Cardboard Packaging using GCxGC–HRTOF–MS with EI and PI
Introduction
Migration of mineral oil from packaging into food has become a health concern, especially since mineral oil affects the liver and lymph nodes. There are two types of mineral oil: mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). Both types are generally measured using online coupled liquid chromatography–gas chromatography–flame ionization detection 2only to separate and detect target fractions, and it may miss other important, unexpected compounds.
By contrast, two-dimensional gas chromatography–high-resolution time-of-flight mass spectrometry (GCxGC–HRTOF–MS) is a comprehensive technique for analyzing complex samples. Using EI with this method allows for NIST database searches. Moreover, using a combination of high-resolution molecular-ion information generated via soft-ionization techniques with an EI NIST database search can result in more-reliable assignments. In this study, we used GCxGC–HRTOFMS with EI and photoionization (PI) soft-ionization techniques to identify compounds in cardboard.
Experiment
Sample preparation methods are shown in Figure 1. We sampled 1 g of the inside surface of the cardboard packaging for a commercial pancake batter mix into a vial, added 10 mL hexane and ethanol (1:1 volume ratio), and soaked it overnight. Then we collected the solvent into another vial and added 0.5 mL water. Next, we collected the top supernatant and added Na2SO4. After 1 hour, we collected the final supernatant and measured it via GCxGC–HRTOF–MS. Measurement conditions are shown in Table 1.