Application of the NU-1000 coated SPME fiber on analysis of trace organochlorine pesticides in water

Herein, a novel solid-phase microextraction (SPME) fiber based on the NU-1000 sorbent was developed for direct immersion extraction of organochlorine pesticides (OCPs) in water samples. As a kind of metal-organic framework, the NU-1000 possessed the mesoporous channels which were beneficial for the mass transfer of target analytes. Extraction equilibrium was achieved rapidly with the optimal extraction time of 30 min. The NU-1000 coated fiber with a high specific surface area showed better extraction efficiencies than commercial fibers (65 μm PDMS/DVB or 85 μm PA) towards OCPs, with the enrichment factors of the NU-1000 coated fiber 2-20 times higher than the latter. NU-1000 coated fiber showed higher extraction efficiencies toward polycyclic aromatic hydrocarbons (PAHs) than OCPs and nitrobenzenes. This indicated that π-π interaction and CH-π interaction between pollutants and aromatic groups of the NU-1000 contributed to the high extraction efficiencies. Under the optimal conditions (extraction at 40 °C for 30 min and desorption at 260 °C for 6 min), the NU-1000 coated fiber coupled with gas chromatography-mass spectrometry (GC-MS) exhibited satisfied analytical performance on analysis of OCPs, with a wide linear range (0.1-2000 ng L-1), low limits of detections (LODs, 0.011-0.058 ng L-1), and good reproducibility and repeatability. The established method has been successfully applied to the determination of OCPs in surface water with good sensitivity and recoveries, which proved the great promise of the NU-1000 on the extraction of organic pollutants with conjugated groups.