Development of multiple monolithic fiber solid-phase microextraction and liquid chromatography-tandem mass spectrometry method for the sensitive monitoring of aminoglycosides in honey and milk samples.

A simple and sensitive method for the simultaneous extraction and determination of six aminoglycosides in honey and milk samples was developed using multiple monolithic fiber solid-phase microextraction and liquid chromatography with tandem mass spectrometry. The multiple monolithic fibers based on poly(methacrylic acid-co-ethylenedimethacrylate) monolith as the extraction medium was used to concentrate target analytes. Because there were abundant carboxyl groups in the monolith, the monolithic fibers could extract aminoglycosides effectively through cation-exchange and hydrophobic interactions. To obtain optimum extraction performance, several extraction parameters including desorption solvent, adsorption and desorption time, pH value and ionic strength in sample matrix, were investigated in detail. Under the optimized extraction conditions, the limits of detection of the proposed method were 0.10-0.30 and 0.23-0.59 μg/kg for honey and milk samples, respectively. Satisfactory linearity was achieved for analytes with the coefficients of determination above 0.99. At the same time, the developed method showed acceptable method repeatability and reproducibility. Finally, the proposed method was successfully applied to the determination of aminoglycosides in real honey and milk samples. Recoveries obtained for the determination of six target analytes in spiking samples ranged from 67.9 to 110%, and the relative standard deviations were in the range of 1.2-11%.