Ionic liquid-assisted synthesis of triazine covalent organic frameworks for selective enrichment and sensitive detection of nonsteroidal anti-inflammatory drugs in urine and river water.

BACKGROUND

The overuse of nonsteroidal anti-inflammatory drugs (NSAIDs) has raised public health and environmental concerns, and their concentrations are low in environmental and biological samples, where complex sample matrices can interfere with analytical accuracy, creating an urgent need for a simple, effective, and sensitive method to detect NSAIDs in complex samples. Covalent organic frameworks (COFs) have emerged as promising adsorbents owing to their tunable pore structures and abundant functional groups. Nevertheless, synthesizing COFs that simultaneously exhibit high adsorption performance and enable sensitive detection of NSAIDs remains a remarkable challenge.

RESULTS

To address this, we synthesized triazine COFs with the assistance of an ionic liquid (IL), termed T-IL-COFs, and employed them as adsorbents for enriching and detecting various NSAIDs. For comparison, W-COFs (lacking IL assistance and triazine units) and T-COFs (containing triazine groups but synthesized without IL) were also prepared. Compared with these two COFs, T-IL-COFs contained triazine units and exhibited larger specific surface areas and pore sizes, enhancing their adsorption performance and selectivity. Adsorption mechanisms were examined using multiple spectroscopic techniques, revealing that interactions were driven by π-π stacking, hydrophobic, electrostatic, and hydrogen-bonding forces. A T-IL-COF-based high-performance liquid chromatography-ultraviolet (HPLC-UV) method was then developed for dispersive solid-phase extraction of NSAIDs. The proposed method exhibited excellent linear ranges (ibuprofen: 1-800 ng/mL; flurbiprofen and ketoprofen: 0.5-800 ng/mL), high enrichment factors (50-81), low limits of detection (0.12-0.33 ng/mL), and excellent recoveries (80.51%-104.70%) in urine and river water samples.

SIGNIFICANCE: This study presents an alternative strategy to enhance the adsorption performance and selectivity of COFs for NSAIDs by introducing functional groups and increasing the specific surface area and pore size. Moreover, it offers an efficient HPLC-UV method for the selective enrichment and sensitive detection of NSAIDs in environmental and biological samples.