Graphene oxide-starch-based micro-solid phase extraction of antibiotic residues from milk samples.

Highlights • Micro-solid phase extraction is used for detection of antibiotics in milk samples. • Extraction is carried out using graphene oxide–starch–based nanocomposite. • The extracted antibiotics are analyzed by HPLC-UV. • The graphene oxide–starch–based nanocomposite shows high efficiency. • The extractive phase extracts antibiotics without protein precipitation from milk. Abstract In this study, a method was described for the extraction of three antibiotic residues from cow milk samples using a graphene oxide–starch–based nanocomposite. The prepared nanocomposites were employed as an extractive phase for micro-solid phase extraction of antibiotics from cow milk samples. The extracted antibiotics, i.e. amoxicillin, ampicillin and cloxacillin, were subsequently analyzed by high-performance liquid chromatography–ultraviolet detection (HPLC–UV). Important variables associated with the extraction and desorption efficiency were optimized. High extraction efficiencies for the selected antibiotics were conveniently achieved using the starch–based nanocomposite as the extractive phase. The developed method was validated according to the European Commission Decision 2002/657/EC by spiking the selected antibiotics to the blank milk samples. The limits of quantitation (2.7–5.0 μg kg−1) were calculated for the selected penicillin group in milk samples and their quantities are lower than the maximum residue limits (MRLs). The obtained results indicate the remarkable efficiency of the graphene oxide–starch–based nanocomposite performance toward the selected antibiotics. The relative standard deviations of intra and inter–day analysis are less than 3.3 and 6.1%, respectively. Moreover, trueness of method was successfully accomplished via the recovery assays (88–102%) in the fortified blank milk samples with three different concentration levels (MRL, 1.5 MRL and 3 MRL μg kg-1). In overall, the proposed method was a promising alternative for analysis of selected three antibiotics in variety milk samples, due to the effective and easy-to-perform method and acceptable relative recovery in the range 83–105%. [ABSTRACT FROM AUTHOR]