A heteropore covalent organic framework for highly selective enrichment of aryl-organophosphate esters in environmental water coupled with UHPLC−MS/MS determination

The identification of an increasing number of aryl organophosphate esters (aryl-OPEs) in environmental samples has led to growing attention recently. Due to the potential adverse effects on human health and environment, development of new analytical methods for sensitive and selective determination of aryl-OPEs in complex matrices is urgently needed. Here, a novel analytical method for the identification and determination of trace amounts of aryl-OPEs in water samples is developed by using melamine sponge@heteropore covalent organic framework (MS@HCOF) based on vortex-assisted extraction (VAE) prior to UHPLC−MS/MS analysis. The MS@HCOF was rationally designed and synthesized through an in-situ growth strategy and exhibited superior selectivity toward aryl-OPEs compared with that of MS@single-pore COF (MS@SCOF) due to steric effect. A systematic optimization was conducted on important parameters of VAE, resulting in the successful extraction of nine aryl-OPEs in just 6 min. Under optimized conditions, the limits of detection (S/N=3) and quantification (S/N=10) were within the ranges of 0.001−0.027 and 0.005−0.091 ng/L for nine aryl-OPEs, respectively. The validated method was proven applicable to real water samples, i.e., the recoveries were 65.3−119.5% for seawater, 59.4−112.9% for effluent, and 76.0−117.4% for tap water. Furthermore, the adsorption mechanisms were explored through density functional theory (DFT) calculations. DFT results revealed that a notable selective enrichment capacity of MS@HCOF towards aryl-OPEs stems from π-π conjugation and hydrogen bonding. The established method benefits from the advantages of high selectivity and sensitivity for the ultra-trace determination of aryl-OPEs. The selective extraction of aryl-organophosphate esters (aryl-OPEs) with different sizes from complex environmental water has been a pressing concern in the field of environmental monitoring. Covalent organic frameworks (COFs) are a novel type of crystalline porous material that have been garnered significant attention in recent years. Here, we reported a novel melamine sponge@heteropore COF (MS@HCOF) with dual-pores. The MS@HCOF exhibited high selectivity for the extraction of aryl-OPEs from environmental water samples. The heteropore structure and ultra-hydrophobicity of MS@HCOF served as the basis for achieving high selectivity and fast extraction (only 6 min). This highlighted the potential of designing COFs for the analysis of aryl-OPEs, presenting new methods for research in this field.