Development of ferrofluid mediated CLDH@Fe3O4@Tanic acid- based supramolecular solvent: Application in air-assisted dispersive micro solid phase extraction for preconcentration of diazinon and metalaxyl from various fruit juice samples

A supramolecular ferrofluid has been applied in air-assisted dispersive micro solid phase extraction method (SUPR-FF-AA-DMSPE) for the residual determination of two pesticides (diazinon and metalaxyl) prior to GC-FID. For this purpose, a magnetic calcined layered double hydroxide (CLDH(Zn-Fe)@Fe3O4) sorbent was modified with the tannic acid (TA) to produce a bio-sorbent. The ferrofluid was easily prepared through the combination of biosorbent and the supramolecular solvent as a carrier liquid. The ferrofluid was rapidly sucked up and injected 5 times using a syringe in the sample solution to improve the mass transfer of the analytes into the sorbent and achieve the fast extraction time. The characterization of CLDH (Zn-Fe)@Fe3O4@TA was investigated by XRD, FT-IR spectroscopy, FESEM and EDS. Influence parameters on the extraction of pesticides were investigated (pH 8; volume of supramolecula solvent 8 mu L.; amount of sorbent 10 mg; pulling and pushing numbers 5 times; volume of the eluent 100 mu L). Under the optimized conditions, the calibration curves found to be linear in the range of 0.6-2000 and 2-2000 mu g L-1 with correlation coefficients > 0.9990 for diazinon and metalaxyl, respectively. The limits of detection (S/N = 3) and limit of quantification (S/N = 10) were obtained 0.2 and 0.8 mu g L-1 and 0.6 and 2 mu g L-1 for diazinon and metalaxyl, respectively. The intra-day and inter-day precisions (RSDs %) (50 pg L-1, n = 6) were 6.5-7.1% and 7.7-8.5%, respectively. The preconcentration factors (PFs) were achieved to be 500. Finally, the proposed method was successfully applied to determine diazinon and metalaxyl in fruit juice and farm water samples with good recoveries in the range of 85-96.6%.