Exploration of a novel triazine-based covalent organic framework for solid-phase extraction of antibiotics

Abstract

Covalent organic frameworks (COFs) are a new class of porous materials with a large surface area and potential superiority in sample pretreatment. Herein a novel triazine-based COF named SCAU-1 was fabricated via a hydrothermal method, and SNW-1 was also prepared as a contrastive COF material. After characterization, SCAU-1 was used as solid-phase extraction (SPE) adsorbent to concentrate five sulfanilamides (SAs) and four tetracyclines (TCs). Several parameters were investigated in the extraction process, including the amount of adsorbent, the flow rate, the washing and elution solvent, the loading capacity and breakthrough volume. After detected by UPLC-MS/MS, the results revealed that SCAU-1 showed high extraction efficiency towards the selected antibiotics. According to the comparison with SNW-1, SCAU-1 showed better performance for the adsorption of TCs. While for SAs, the recoveries of SCAU-1 is close to that of SNW-1. The LODs are from 0.031 to 0.55 μg L^-1, and the recoveries are from 88.0% to 93.4% for SCAU-1 with the RSDs ranging from 2.5% to 4.8%. The results demonstrated that SCAU-1 is a kind of promising adsorbent for the enrichment of organic pollutants.

Fig. 1. (a) The synthesis scheme of SCAU-1; (b) the FTIR spectrum of the prepared SCAU-1; (c) scanning electron micrograph of SCAU-1; (d) nitrogen adsorption/desorption at 77 K of the SCAU-1 powder.

Fig. 2. (a) Effect of the amount of sorbents on the recoveries of antibiotics (conditions: washing solvent, 2 mL water; elution solvent, 2 mL MeOH; spiked level, 5 μg L⁻¹); (b) effect of flow rate on the recoveries of antibiotics (conditions: amount of sorbent, 60 mg; the other conditions were the same as above).

Fig. 3. (a) Effect of washing solvent on the recoveries of antibiotics (conditions: amount of sorbent, 60 mg; elution solvent, 2 mL MeOH; spiked level, 5 μg L⁻¹); (b) the selected ion chromatogram of the diluted waste water sample spiked at 5 μg L⁻¹; (c) effect of elution solvent on the recoveries of antibiotics (conditions: amount of sorbent, 60 mg; washing solvent, 2 mL water; spiked level, 5 μg L⁻¹).

Fig. 4. Extraction efficiency comparison of the prepared COFs with the commercial HLB (conditions: amount of sorbent, 60 mg; washing solvent, 2 mL water; elution solvent, 2 mL MeOH + NH₃; spiked level, 5 μg L⁻¹).