Direct Immersion-Solid-Phase Microextraction Coupled to Gas Chromatography-Mass Spectrometry and Response Surface Methodology for Nontarget Screening of (Semi-) Volatile Migrants from Food Contact Materials.

Toward a more rigorous inspection of food contact materials, the importance of sample preparation for nontarget screening should be addressed. Direct immersion-solid-phase microextraction coupled to gas chromatography mass spectrometry (DI-SPME-GC-MS) was optimized for nontarget screening of migrants in 3% acetic acid, 10% ethanol, and 95% ethanol food simulants by response surface methodology (RSM) in the present study. Optimum conditions were DVB/CAR/PDMS fiber, no pH adjustment for 10% and 95% ethanol simulant but pH adjustment to 7 for 3% acetic acid simulant, no salt addition, 5 min preincubation, 55 min extraction at 70 °C, and 8 min desorption at 250 °C. In addition, 9.5 times dilution of 95% ethanol samples prior to extraction was required. pH modification of 3% acetic acid samples was found to be critical for the extraction of amines. The proposed methodology was then evaluated by determining the limit of detection (LOD) as well as repeatability of 35 food contact materials-related substances. Except for those amines and diols which have a relatively high LOD, the LODs of the rest of the substances were 0.1-14.1 μg/kg with a precision of 1.9-23.0% in 10% ethanol and were 0.1-20.2 μg/kg with a precision of 2.5-19.6% in 3% acetic acid simulant. The LOD and precision in 95% ethanol simulant were 0.7-163.7 μg/kg and 1.4-26.8%, respectively. The proposed method can be applied for an overall screening of migrants from these three simulants at even trace levels, though attention should be paid to some specific analytes, e.g., diols and amines, which could have a high LOD and toxicity.