Tailoring amine-rich porous monolith for the miniaturized solid phase extraction of phenolic environmental estrogens

Developing an efficient miniaturized solid phase extraction (μ-SPE) method is essential in the accurate and reliable monitoring of trace phenolic environmental estrogens (PEEs) in environmental waters. In this study‌, a lab-built multichannel in-tip microextraction apparatus (MIMA) incorporating an amine-rich porous monolith (APA) formed in situ within a pipette tip (200 μL) was developed for efficient capture of PEEs in environmental waters. Due to the abundant amino groups, the APA exhibited satisfactory microextraction performance through multiple interactions. The maximum adsorption amounts and extraction efficiencies were in the ranges of 2.63-10.0 mg/g and 70.9-95.8%, respectively. At the same time, the APA presented excellent batch-to-batch preparation reproducibility with the RSDs varied from 2.8% to 8.6% and satisfactory reusability (could be reapplied at least 40 times). Furthermore, the adsorption characteristic and microextraction mechanism were systematically investigated. Under the most beneficial microextraction parameters, the established APA@MIMA method enabled on-field sample preparation of the studied PEEs in waters prior to HPLC/DAD determination, offering wide working ranges, low limits of detection (0.0023-0.013 μg/L) and satisfactory method precision (RSDs below 10%). Confirmatory experiments and fortifying recovery further validated the method accuracy. Additionally, method greenness was comprehensively assessed based on analytical GREEnness for sample preparation, assessment of greenness and green analytical process index, and the corresponding values were 0.64, 0.50 and 79. The present work highlights the promising application of APA@MIMA technique in the on-site extraction of PEEs in environmental waters while overcoming the limitations of lab-based sample preparation methods.