A simple graphene-based pipette tip solid-phase extraction of malondialdehyde from human plasma and its determination by spectrofluorometry

Determination of malondialdehyde (MDA) in human blood plasma is important because of its role as a biomarker of lipid peroxidation in biological and medical sciences. In this work, a miniaturized graphene-based pipette tip solid-phase extraction technique was developed for very efficient extraction of MDA as its dithiobarbituric acid (TBA) adduct from human plasma. Two milligrams of graphene as sorbent were placed into a pipette tip and MDA-TBA compound was extracted and preconcentrated by it, after 4 repeated aspirating/dispensing cycles, then the column was eluted with 80 mu L of dimethyl sulfoxide by 4 repeated aspirating/dispensing cycles and elusion was measured spectrofluorimetrically. Various effective parameters such as type and volume of eluent solvent, temperature, sample volume, number of cycles of extraction and desorption, derivatization reaction time, and pH of the sample solution were investigated and optimized. Under optimum conditions, a linear calibration curve was obtained in the range of 0.5-90 mu g L-1 (r (2) = 0.991) with a detection limit of 0.3 mu g L-1. The relative standard deviations for 8 replicate measurements of 10 and 40 mu g L-1 of MDA were found to be 4.51 and 3.78 % respectively. The developed protocol was successfully applied to the determination of MDA in a human blood plasma sample.