Cellulose-coated CoFe2O4 nanoparticles as an adsorbent for extraction and preconcentration of bioactive compounds in vinegars

In this work, an extraction and preconcentration flow system using mini-column packed with cellulose-coated CoFe2O4 was developed for the determination of bioactive compounds in vinegar samples by high-performance liquid chromatography with diode array detector (HPLC-DAD). The CoFe2O4 nanoparticles were synthetized by a sonochemical method and coated with cellulose biopolymer. Both synthetized nanoparticles and nano-composites were characterized employing the techniques of X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry (TG) and Derivative Thermogravimetry (DTG). The flow system was optimized employing two-level full factorial design and Doehlert matrix, in which the established optimum conditions were: adsorbent mass of 254 mg, eluent concentration of 92% (v/v methanol/water) and sampling flow rate of 2.0 mL min(-1). In these conditions, the flow system allows the determination of 12 bioactive compounds with limits of detection and quantification that varied in the range of 0.0009-0.091 mg L-1 and of 0.0028-0.276 mg L-1, respectively. Enrichment factors (EF) were in the range of 2.31-63.72. The proposed flow system was applied for the analysis of 24 vinegar samples of brands locally available in Salvador City, Bahia, Brazil.