Extraction of nucleobases, nucleosides and nucleotides by employing a magnetized graphene oxide functionalized with hydrophilic phytic acid and titanium(IV) ions

A magnetite@graphene oxide nanocomposite was first coated with polyethylenimine and then modified with phytic acid and titanium(IV) ions. The high loading with Ti(IV) and the good hydrophilicity of PEI and PA result in a material that can be applied to the efficient extraction of highly polar nucleobases, nucleosides and nucleotides. The physicochemical properties of the composite were investigated by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, water contact angle measurements, thermogravimetric analysis, and vibrating sample magnetometry. A series of parameters that affect extraction and elution under the conditions of immobilized metal affinity chromatography (IMAC) and hydrophilic interaction liquid chromatography (HILIC) were examined. The analytes were eluted from the nanocomposites using 10 mM trisodium phosphate as the elution solution in the IMAC mode, and 50% methanol-water as elution solution in the HILIC mode. Figures of merit include (a) an intra-day precision of 0.1–1.0% in the IMAC mode; (b) an intra-day precision of 0.4%–0.8% in the HILIC mode; (c) detection limits between 1.8–2.8 ng mL−1 in the IMAC mode; and (d) detection limits of 4.0–10.5 ng mL−1 in the HILIC mode. The method was applied to the extraction of the nucleotides cytidine-5′-monophosphate (CMP), uridine-5′-monophosphate (UMP), guanosine-5′-monophosphate (GMP), and adenosine-5′-monophosphate (AMP), and the nucleobases and nucleosides hypoxanthine, adenosine, cytosine, inosine and cytidine from Cordyceps sinensis, Lentinus edodes and plasma samples.