A Novel Gully-like Surface of Stainless-Steel Fiber Coated with COF-TPB-DMTP Nanoparticles for Solid-Phase Microextraction of Phthalic Acid Esters in Bottled Tea Beverages

A covalent organic framework TPB-DMTP was physically coated onto the gully-like surface of stainless-steel fiber. The fabricated TPB-DMTP-coated stainless-steel fiber was used to extract five phthalic acid esters (PAEs) prior to the GC-FID separation and determination in bottled tea beverages. The developed SPME-GC-FID method gave limits of detection (S/N = 3) from 0.04 µg·L^-1 (DBP) to 0.44 µg·L^-1 (BBP), with the enrichment factors from 268 (DEHP) to 2657 (DPP). The relative standard deviations (RSDs) of the built method for inter-day and fiber-to-fiber were 4.1-11.8% and 2.3-9.9%, respectively. The prepared TPB-DMTP-coated stainless-steel fibers could stand at least 180 cycles without a significant loss of extraction efficiency. The developed method was successfully applied for the determination of trace PAEs in different bottled tea beverages, with recoveries from 85.5% to 115%.