Amine-functionalized MIL-101(Fe) for highly selective and efficient extraction of phenoxy carboxylic acid herbicides from environmental water and rice samples

Phenoxy carboxylic acid herbicides (PCAs) are widely used in agricultural production. However, due to their potential threat to human health, it is necessary to develop efficient analysis method for monitoring PCA concentration in environment and food samples. Based on dispersive micro-solid phase extraction (D-μ-SPE) with amine-functionalized metal–organic framework MIL-101(Fe)-NH 2 , a selective, sensitive, and cost-efficient method was proposed for the extraction of PCAs from environmental water and rice samples in this study. From the perspective of adsorption kinetics and isotherms, interaction mechanisms between MIL-101(Fe)-NH 2 and PCAs were investigated. Key parameters of D-μ-SPE procedure including adsorbent dosage, solution pH, ionic strength, eluting solution, and washing solutions were optimized. Using of small amount of MIL-101(Fe)-NH 2 could achieve desirable extraction effect due to its large surface area and multiple interactions with PCAs. Under the optimized D-μ-SPE conditions, calibration curves of 8 PCAs were linear within a concentration range of 0.05–5 ng/mL for water samples ( r 2 > 0.9898) and 0.5–50 ng/g for rice samples ( r 2 > 0.9879). Limits of detection of water and rice samples were as low as 0.004–0.008 ng/mL and 0.05–0.1 ng/g, respectively. The recoveries of 8 PCAs ranged from 83.0 to 109.3%. Both inter- and intra-day relative standard deviations were less than 10.3%. Our proposed method was successfully employed in actual environmental water and rice samples.