One-step in-situ growth of histidine-modified ZIF-90 on natural eggshell membrane for efficient extraction of p-nitrophenol and 3-methyl-4-nitrophenol in human urine and environmental water.

Monitoring of p-nitrophenol (PNP) and 3-methyl-4-nitrophenol (PNMC) in human urine and environmental water is of great importance for human health assessment and environmental protection, as they are both urinary metabolites of some poisonous pesticides and priority environmental pollutants. However, efficient extraction of trace levels of PNP and PNMC from complex matrices remains challenging. This study presented the synthesis of histidine-modified ZIF-90 on natural eggshell membrane (ESM@His-ZIF-90) via a facile one-step in-situ growth strategy, and its application as an adsorbent for dispersive membrane extraction (DME) of PNP and PNMC in human urine and environmental water. The ESM@His-ZIF-90 exhibited extraordinary extraction efficiency due to the abundant adsorption activity of His-ZIF-90 and the rapid separation of ESM from sample solution. The adsorption behavior of ESM@His-ZIF-90 towards two nitrophenols followed Langmuir isotherm model and pseudo-second-order kinetic model. Notably, the ESM@His-ZIF-90 demonstrated fast adsorption kinetics with adsorption equilibrium achieved in only 10 min. The results of FT-IR, XPS and DFT calculations revealed that the rapid adsorption was attributed to the synergistic effect of π-π EDA, hydrophobic and hydrogen bonding interactions. By coupling ESM@His-ZIF-90-based DME with HPLC-UV, good linearity (R ≥ 0.9943) and low limits of detection of 0.25-0.65 μg L were obtained. Finally, the method was successfully applied to the detection of PNP and PNMC in human urine and environmental water, and the method recoveries ranged from 83.0 to 106.1 % with RSDs lower than 7.2 %.