Exploration of a modified pretreatment process coupled with GC-MS/MS for determination of 18 phthalates in edible oils†

Abstract

Phthalates (PAEs), which are pollutants that most easily migrate from plastic packages to edible oils, have received increasing attention. In this work, a sample preconditioning method was proposed and explored, involving a single-step extraction using a methanol and ethyl hexanoate mixed solvent, followed by clean-up with a mixed absorbent of graphitic carbon nitride (g-C₃N₄) and N-propyl ethylenediamine (PSA), for the determination of 18 PAEs in oil samples through GC-MS/MS analysis. The triazine ring structure and conjugated aromatic heterocyclic accumulation structure of g-C₃N₄ and the amino-rich structure of PSA can provide hydrogen bonds, conjugated π–π interactions, and hydrophobic effects for the removal of interferences such as organic acids, aliphatic acids, and pigments. To achieve optimal analytical performance, key extraction and purification parameters that may affect the pretreatment efficiency—such as the extraction solution, its volume ratio, extraction temperature, extraction time, and the amount of the clean-up absorbent—were systematically explored and optimized. When applied to edible oil analysis, an excellent linear range from 0.2 to 8.0 mg kg⁻¹ with a preferable coefficient of determination (R² > 0.9989) and satisfactory sensitivity (LOD and LOQ ranging from 0.0002 mg kg⁻¹ to 0.08 mg kg⁻¹ and 0.0004 mg kg⁻¹ to 0.2 mg kg⁻¹, respectively) were obtained. Moreover, a relatively satisfactory recovery varying from 71.4% to 107.9% and the corresponding repeatability ranging from 0.3% to 6.8% were acquired. Furthermore, this work offers a new idea for exploring the application of novel nanocomposites in the pretreatment process.