In-situ decomposed nanofluids dispersive liquid-phase microextraction for detection of seven triazole fungicidets in fruit juices and tea drinks

Abstract

A novel, eco-friendly and efficient in-situ decomposed nanofluid dispersive liquid-phase microextraction approach was developed to detect myclobutanil, flusilazole, hexaconazole, penconazole, epoxiconazole, paclobutrazol and diniconazole in tea drinks and fruit juices by high-performance liquid chromatography. Various new nanofluids were prepared physically using multi-walled carbon nanotubes and hydrophilic deep eutectic solvents, with acetic acid/ DL-lactic acid/glycerol/propylene glycol/ethylene glycol/urea and choline chloride used as the hydrogen-bond donor and acceptor respectively. The nanofluids in the sample solutions were decomposed in-situ, while multi-walled carbon nanotubes and deep eutectic solvents served as the adsorbent and carrier/stabilizer/dispersing agent, respectively. One-factor-at-a-time tests showed the optimized parameters for extracting triazole fungicides were 10 mL and pH 6 of sample solutions, 300 μL of nanofluids ([choline chloride: ethylene glycol]: multi-walled carbon nanotubes = [1:2] : 20), 8% sodium chloride, 9 min of vortex, 5 min of centrifugation, 1000 μL of eluent methanol, and 2 min of elution. The new approach performed well with linear range, relative recovery, detection limit, quantification limit, and inter- and intra-day relative standard deviations of 10-10000 μg/L, 70.03-107.14%, 3.34-8.30 μg/L, 10-25 μg/L, < 11.30% and <13.01%, respectively. The adsorption isotherms of triazole fungicides were well fitted by a Freundlich model and a pseudo-second-order kinetic model, revealing that the adsorption process accorded with the theories of multilayer adsorption and chemical adsorption. This environmental approach can triumphantly detect residual triazole fungicides in real tea drinks and fruit juices, and is a potentially promising technique for detecting food matrices.