Preparation of TP-PA-coated needle trap device for determination of polychlorinated biphenyls in milk combined with gas chromatography

The solvothermal approach was used to create a three-dimensional covalent organic framework (TP-PA) using p-phenylenediamine (PA), 1,3,5-triformyl phoroglucinol (TP), and anhydrous ethanol as the solvent. It was utilized as a coating material for needle trap devices (NTD) to determine five polychlorinated biphenyls (PCBs) from milk coupled with gas chromatography (GC). The results displayed that TP-PA presented excellent extraction performance to PCBs owing to its abundant micro/mesopores structure, high specific surface area and good chemical and thermal stability. The proposed needle-type micro-extraction (NTME)-GC method had wide linearity (0.025–200 μg L −1 ) with R 2 ≥ 0.9928, low limits of detection (0.0072–0.0146 μg L −1 ), and good single device repeatability and device-to-device reproducibility with the relative standard deviations (RSDs) below 7.07 %. It was applied to detect five trace PCBs in milk, and satisfactory spiked recoveries were obtained (79.7 %∼96.4 %) with relative standard deviations less than 11.9 %. The above results indicated that the method has excellent application potential for detecting PCBs in food.