Ultra-stable Co3O4/NiCo2O4 double-shelled hollow nanocages as headspace solid-phase microextraction coating for enhanced capture of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are persistent toxic pollutants that tend to accumulate in food and cause damage to human health. This work reports the ultra-sensitive detection of PCBs in beverage samples (green tea, honey, and bottled drinking water) by headspace solid-phase microextraction (HS-SPME) coupled with a gas chromatography-flame ionization detector (GC-FID). The Ultra-stable Co3O4/NiCo2O4 double-shelled hollow nanocages (DSHNC) as SPME fiber coating were synthesized with pyrolysis of zeolitic imidazolate framework-67/layered double hydroxide precursor. The fiber coating material Co3O4/NiCo2O4 DSHNC demonstrated excellent thermal stability (＞1000 °C) and long usage lifespan (≥160 times). The extract ability to polar PCBs was significantly enhanced by oxygen-containing groups, π-π stacking, and electrostatic interaction. Experiments results illustrated that the adsorption is controlled by chemical adsorption with a monolayer molecular adsorption. The HS-SPME-GC-FID method possessed good linearity (R2 ≥ 0.9961) in the linear range of 0.10–50000 pg·mL−1 and low detection limits (0.03–1.5 pg·mL−1). The enrichment factors were determined between 6884 and 9765. The method was successfully applied to enrich PCBs in real samples and obtained a good recovery rate in the range of 78.26–112.1 %.