Magnetic dispersive micro solid-phase extraction of trace Rhodamine B using imino-pyridine immobilized on iron oxide as nanosorbent and optimization by Box-Behnken design

In present study a magnetic dispersive micro-solid-phase extraction method (MD-mu-SPE) based imino-pyridine immobilized on iron oxide (gamma-Fe2O3) as an efficient sorbent was developed for preconcentration and quantification trace amount of Rhodamine B in food and cosmetic products samples. The sorbent due to its high surface area, excellent adsorption capacity, good dispersion ability and high super-paramagnetic property was successfully synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM) techniques. Various parameters, which probably influence efficiency of extraction were investigated and optimized by the box behnken design under response surface methodology. The analytical parameters such as precision, accuracy and linear working range were also determined at optimal experimental conditions. Under the optimum conditions, a linear calibration graph in the range of 5-200 ng mL(-1) of Rhodamine B with r = 0.9993 (n = 10) was obtained. Detection limit based on three times the standard deviation of the blank (3S(b)) was 1.6 ng mL(-1) (n = 5) and the relative standard deviation (% RSD) for 50 ng of target dye was 2.27% (n = 5). The applicability of the developed procedure was successfully evaluated by the determination of the target dye in soft pastel, chili powder, and hand washing liquid soap samples. The recoveries of the target analyte ranged from 90.8% to 96.8%, with the RSDs between 2.4% and 4.3%.