Rapid Simultaneous Quantification of Four Typical Phthalate Esters in Complex Food Matrices via Thermal Desorption–Dielectric Barrier Discharge Ionization Mass Spectrometry

Abstract

Conventional analytical methods for detecting and quantifying phthalate esters (PAEs) in foods generally require lengthy sample pretreatment procedures and suffer from severe matrix interferences. To address these shortcomings, a fast analytical platform based on a thermal desorption unit that is directly interfaced with dielectric barrier discharge ionization mass spectrometry (TD-DBDI-MS) was developed. The integration of a heated nitrogen purge system effectively suppressed atmospheric background interference and improved signal stability. Moreover, a simplified liquid–liquid extraction pretreatment protocol was established that eliminates the need for centrifugation and solid-phase extraction (SPE) cleanup steps. The complete analysis cycle time per sample was reduced by approximately 55% compared to conventional GC-MS/LC-MS workflows, and each analysis by TD-DBDI-MS was completed in only 10 seconds. The method exhibited excellent linearity for four typical PAEs in the range of 0.5–200.0 μg/L with correlation coefficients (R2) > 0.998. The limits of detection (LOD) ranged from 0.11 to 0.52 μg/kg, spike recoveries were between 82% and 106%, and relative standard deviations (RSDs) were <10%. Application to 19 commercially available food samples revealed widespread PAE contamination, with butyl benzyl phthalate (BBP) being detected in every sample. Contamination levels followed the order premade dishes > milk > sugary beverages. PAE migration levels from plastic bag packaging were significantly higher than those from plastic bottle and carton packaging. Fortunately, the measured PAE concentrations were all well below the specific migration limits (SMLs) specified in China’s GB 5009.271-2016 regulation and EU Regulation 10/2011. This rapid, efficient, and robust method provides a novel approach for large-scale screening of PAEs in complex food matrices.