Preparation of cationic microporous organic network for efficient solid-phase extraction of nonsteroidal anti-inflammatory drugs from environmental water and milk samples

The overuse of nonsteroidal anti-inflammatory drugs (NSAIDs) poses many serious environmental and food safety concerns. Development of effective and sensitive sample pretreatment method for monitoring trace NSAIDs from complex samples is of great significance. Depending on the ionic and aromatic structures of NSAIDs, a cationic microporous organic network (MON) named TEPM-BBDC with large specific surface area, good solvent and thermal stabilities, and numerous interaction sites was designed and prepared for efficient solid-phase extraction (SPE) of four typical NSAIDs (flurbiprofen, ketoprofen, naproxen, and diclofenac sodium) from environmental water and milk samples. By anchoring the ionic groups in the conjugated MON frameworks, the prepared TEPM-BBDC offered good extraction for NSAIDs based on the 7C-7C, hydrophobic, ion exchange, and electrostatic interactions. Under the optimal extraction conditions (initial concentration of each NSAID: 200 g L1; sample volume: 50 mL; desorption solvent: 1.5 mL of MeOH + 1 % NH3 & sdot;H2O; sample loading rate: 5 mL min-1; NaCl concentration: 0 mmol L-1; pH = 5), the proposed TEPM-BBDC-SPE-HPLC-UV method owned wide linear range (0.50-1000 g L-1), low limits of detection (0.10-0.40 g L-1), large enrichment factors (92.2-99.2), good precisions (intra-day and inter-day, RSD% = 1.3-7.8 %, n = 6) and reproducibility (column-to-column, RSD% = 8.0 %, n = 3). The developed method also exhibited good recoveries (83.6-113.4 %) for the determination of NSAIDs in river water, lake water and milk samples. This work not only revealed the potential of TEPM-BBDC for SPE of ionic NSAIDs in complex samples, but also highlighted the prospect of ionic MONs in sample pretreatment.