Magnetic solid phase extraction employing a novel restricted access material based on mesoporous polyaniline coated with hydrophilic monomers and casein for determination of antibiotics in milk samples

In this study was developed a new analytical method for the simultaneous determination of several antibiotics used in cows. For this, the technique of determination of doxycycline (DOX), oxytetracycline (OXY), trimethoprim (TPM) and penicillin G (PC-G) in milk samples was using the magnetic solid phase extraction (MSPE) and analyzing by high performance liquid chromatography (HPLC). Then, the adsorbent material developed was a novel restricted access material based on magnetic mesoporous polyaniline coated with hydrophilic monomers and casein (RA-MMPAni-HM-CAS). The materials of each step of the synthesis were characterized by thermogravimetric analysis, scanning electron microscopy with energy dispersive spectroscopy, X-Rays diffraction and Fourier transform infrared spectroscopy. The chromatographic method developed was using the mobile phase composed by methanol: 50 mM phosphate buffer solution pH 6.6 (45: 55, v/v) in isocratic mode and reverse phase with flow rate at 1.25 mL min−1, temperature at 25 °C, injection volume of 20 μL and ultraviolet detection in 240 nm. The optimized parameters conditions, for the sample preparation were 500 μL of water as washing solvent, 800 μL acetonitrile: acetic acid (7: 3, v/v) as eluent solvent, 1 mL of sample at pH 12.5, 40 mg of RA-MMPAni-HM-CAS of and 1 min stirring on vortex. The method shown to be linear over the concentration range from 8 to 1000 ng mL−1 with coefficients of determination (R2) ≥0.99 for all analytes and recoveries proximity to 100% for TPM, DOX and OXY, and recovery to 93.16% for PC-G. The method developed and validated was applied in real milk samples from various local supermarkets. In conclusion, the results showed that RA-MMPAni-HF-CAS coupled to HPLC was low cost technique, simple and easy to perform. •RA-MMPAni-HM-CAS a new restricted access material for sample preparation MSPE•MSPE coupled to HPLC-DAD was fast, economical and easy-to-perform technique.•A new HPLC method for multidetermination of antibiotics was developed.•Antibiotics were efficiently determined in real milk samples.