Nanocomposite microbeads made of recycled polylactic acid for the magnetic solid phase extraction of xenobiotics from human urine

Nanocomposite microbeads (average diameter = 10–100 μm) were prepared by a microemulsion-solidification method andapplied to the magnetic solid-phase extraction (m-SPE) of fourteen analytes, among pesticides, drugs, and hormones, fromhuman urine samples. The microbeads, perfectly spherical in shape to maximize the surface contact with the analytes, werecomposed of magnetic nanoparticles dispersed in a polylactic acid (PLA) solid bulk, decorated with multi-walled carbonnanotubes (mPLA@MWCNTs). In particular, PLA was recovered from filters of smoked electronic cigarettes after an ade-quate cleaning protocol. A complete morphological characterization of the microbeads was performed via Fourier-transforminfrared (FTIR) spectroscopy, UV–Vis spectroscopy, thermogravimetric and differential scanning calorimetry analysis (TGAand DSC), scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The recovery study of the m-SPEprocedure showed yields ≥ 64%, with the exception of 4-chloro-2-methylphenol (57%) at the lowest spike level (3 μg L −1 ).The method was validated according to the main FDA guidelines for the validation of bioanalytical methods. Using liquidchromatography-tandem mass spectrometry, precision and accuracy were below 11% and 15%, respectively, and detectionlimits of 0.1–1.8 μg L −1 . Linearity was studied in the range of interest 1–15 μg L −1 with determination coefficients greaterthan 0.99. In light of the obtained results, the nanocomposite microbeads have proved to be a valid and sustainable alterna-tive to traditional sorbents, offering good analytical standards and being synthetized from recycled plastic material. One ofthe main objectives of the current work is to provide an innovative and optimized procedure for the recycling of a plasticwaste, to obtain a regular and reliable microstructure, whose application is here presented in the field of analytical chemistry.The simplicity and greenness of the method endows the procedure with a versatile applicability in different research andindustrial fields.