Facile preparation of a magnetic porous organic frameworks for highly sensitive determination of eight alkaloids in urine samples based UHPLC-MS/MS

Abstract

In this work, a facile strategy for the preparation of magnetic porous organic framework (Ni@POFs) was proposed by the reduction of Ni ions on its skeleton in situ. The properties of the material were confirmed by X-ray diffraction, vibrating sample magnetometer, infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The prepared Ni@POFs exhibits a strong magnetism and high extraction efficiency for targeted alkaloids. All the key factors that affect the extraction/desorption efficiency of the alkaloids onto the Ni@POFs material, such as sorbent amount, extraction time, sample pH and desorption condition, were investigated with the help of response surface methodology. In combination with magnetic solid phase extraction and ultra performance liquid chromatography-tandem mass spectrometry analysis, a novel method for the quantitative analysis of alkaloids in urine samples was proposed. The limits of detection and limits of quantitation for the eight alkaloids were found to be in the range of 0.9–6.0 and 3.0–20 pg mL−1, respectively. The recoveries of spiked urine samples were in the range of 93.5–99.2% with RSDs less than 6.9%. The proposed method was successfully applied to analyze the metabolites in patient’s urine after the oral administration of berberine.