The water - resistant zeolite imidazolate framework 67 is a viable solid phase sorbent for fluoroquinolones while efficiently excluding macromolecules

The determination of antibiotics in biological samples is compromised by their interaction with proteins. It is showed here that the water resistant zeolite imidazolate framework 67 (ZIF-67) represents a useful sorbent for solid-phase extraction (SPE) of fluoroquinolones (FQs) from biological samples. ZIF-67 is unique in possessing permanent nanoscale porosity and a high surface area. As a result, it efficiently excludes proteins from the inner network but can well adsorb small organic molecules. Its extraction capacity for FQs exceeds that of isostructural ZIF-8, probably due to high affinity for Co(II) ions in ZIF-67. The findings were exploited to design a method for the analysis of FQs, which were extracted from bio-samples by ZIF-67 via SPE. Following elution of the absorbed FQs with NaOH/methanol, they were quantified by HPLC with diode array detection. The assay has a wide linear range that extends from 3.9 to 4000 mu ga <...kgaEuro3/4(1), with detection limits between 1.2 and 2.9 mu ga <...kgaEuro3/4(1). The method was successfully applied to the determination of FQs in manure.