Headspace solid-phase microextraction sampling of endogenous aldehydes in biological fluids using a magnetic metal-organic framework/polyaniline nanocomposite

Nanoporosity, crystal structure, good thermal and mechanical stability, high surface‐to‐volume ratio, nanoscale cavities, and uniform pore topology have made metal‐organic frameworks one of the best class of sorbents for adsorption/separation purposes. In this research, a metal‐organic framework/polyaniline magnetite nanocomposite was synthesized and intercalated by polyaniline by electrophoretic deposition on the surface of a thin steel wire, to prepare a solid‐phase microextraction fiber. It was coupled with gas chromatography‐flame ionization detection and employed for the extraction and determination of aldehydes in biological samples. The magnetic nanocomposite was characterized using scanning electron microscopy, energy dispersive X‐ray analysis, and Fourier transform infrared spectroscopy. Under the optimal experimental conditions, the calibration curves were linear in the range of 0.01‐1 and 0.1‐1 µg/L for hexanal and heptanal, respectively. The limits of detections for hexanal and heptanal were 0.001 and 0.01 µg/L, respectively. Intrafiber repeatability for six replicate analyses of 0.2 µg/L of the analytes was over the range 3.5‐7.1%. Interfiber (fiber‐to‐fiber) reproducibility, calculated by six replicate analyses of the same concentration using three different fibers, and was found to be 10.4‐15.7%. The developed procedure was successfully utilized for the analysis of hexanal and heptanal in human plasma and urine samples.