Sensitive and accurate determination of sialic acids in serum with the aid of dispersive solid-phase extraction using the zirconium-based MOF of UiO-66-NH2 as sorbent

A zirconium-based metal-organic frameworks (MOF), with 2-aminoterephthalic acid as linkers, named UiO-66-NH2, has been synthetized and characterized in a dispersive solid-phase extraction (DSPE) procedure in combination with high-performance liquid chromatography (HPLC) with fluorescence detection (FLD) for the pre-concentration and detection of sialic acids (SAs) in serum samples. In this study, UiO-66-NH2 was employed for the first time as a novel DSPE sorbent for sample pretreatment. Parameters which influence the extraction efficiency such as the amount of MOF, nature of the desorption solvent and its amount, adsorption time and desorption time were investigated and optimized. Under the optimized conditions, better extraction results were obtained by UiO-66-NH2 based DSPE for the extraction of SAs from serum samples than traditional sample preparation methods. Detection limits of the method as low as 0.16 pmol for N-glycolylneuraminic acid (Neu5Gc) and 0.11 pmol for N-acetylneuraminic acid (Neu5Ac) were obtained, with determination coefficients (R-2) higher than 0.9995 for the range 10-1000 pmol L-1, average recoveries of >91.3% at three different spiked levels (1, 5 and 10 ng mL(-1)), and relative standard deviation (RSD) values below 3.4%. The proposed method was demonstrated to be sensitive enough for determination of SAs from bio-samples.