A combination of amino-functionalized fibrous silica (KCC-1-NH2)/effectively and efficiently oxidized graphene oxide (EEGO) nanocomposite for dispersive solid-phase extraction, pre-concentration and fluorescence determination of total para-cresol in plasma samples of chronic kidney disease patients.

ABSTRACT

A novel amino-functionalized fibrous silica (KCC-1-NH2) and effectively and efficiently oxidized graphene oxide (EEGO) nanocomposite has been successfully synthesized. This nanocomposite was applied as a new sorbent in the dispersive solid-phase extraction (-SPE) to the preconcentration of total p-cresyl sulfate (pCS) in human plasma samples. The morphology and basic structure of the proposed nanocomposite were investigated through different techniques including field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and dynamic light scattering (DLS)/zeta potential techniques. The influence of different factors on the extraction efficiency, including the amount of sorbent, sample pH, extraction time, elution solvents and their volume, and desorption time were also investigated. The developed fluorescence-based method offers a linear dynamic range from 0.02 to 6 µg/mL with an acceptable correlation coefficient (R2 = 0.9982) and recovery (80%). The limit of quantification (LOQ) and limit of detection (LOD) were found to be 0.043 and 0.013 µg/mL, respectively. Plasma samples of five chronic kidney disease (CKD) patients were also analyzed and measured pCS concentrations were ranged from 16 to 41 µg/mL. The applicability of the method was successfully tested for the extraction and quantification of pCS from spiked and patients' plasma samples.