In-situ modified polyamide 6 nanofibers for spin-filter solid phase extraction: Effect of azo dye coating on extraction efficiency

Due to their significant surface area and tunable surface chemistry, polymer nanofibers are promising advanced sorbents for miniaturized solid phase extraction of a broad range of model analytes that differ in chemical structures and physical properties. In this study, in-situ modified and coated polyamide 6 nanofibers were evaluated as sorbents for spin-filter solid phase extraction. The modified nanofibers were produced by electrospinning from polymer solutions containing either 3-[dodecyl(dimethyl)ammonio]-1-propanesulfonate (sulfobetaine 12) or tetramethylammonium chloride. Alternatively, the nanofibers were coated with sulfonated azo dyes. This surface modification of nanofibers was identified as a key factor in governing sorbent performance, and led to significantly enhanced extraction efficiency compared to native and uncoated materials. Among the tested sorbents, tartrazine-coated nanofibers exhibited the highest extraction efficiency, particularly for phenolic acids and non-steroidal anti-inflammatory drugs. Recoveries exceeded 90% for most analytes. The developed spin-filter solid phase extraction method coupled with ultra-high performance liquid chromatography with spectrophotometric detection showed good accuracy (85.8–106.6%) and precision (RSD ≤ 4.7%). Applying the method to analyze river water confirmed the suitability of the sorbent for extracting polar xenobiotics prior to chromatographic analysis.