Nanofiltration of small-volume samples (1-10 mL) is an attractive process to concentrate and separate important classes of biochemicals, like peptides or sugars, with molecular weight bellow 1000 Da, in aqueous solutions with high osmotic pressures. In this work, microfluidic tangential flow nanofiltration (micro-TNF) and centrifugal nanofiltration (CNF) techniques are compared, for the concentration of model aqueous solutions of K2SO4, fructose and sucrose, with osmotic pressures (pi) up to 2.6 bar and initial volumes between 3 and 10 mL. Micro-TNF was evaluated for laminar flows with Reynolds numbers between 0.17 and 8.3, while the transmembrane pressure varied from 7 to 34 bar. The CNF was performed at initial pressures of 16 bar and 35 bar. The CNF and the Micro-TNF had a membrane active surface area of 2.6 cm(2) and 6.7 cm(2), respectively. With both techniques, the final concentration factor (CF) decreases with the feed concentration. For low concentrations (pi=0.6 bar) both techniques yield a CF higher than 10. At high concentrations (pi=2.6 bar), CNF is more efficient to concentrate the aqueous solution, achieving CF values 50%-150% larger than those obtained by micro-TNF. This result suggests that CNF has lower concentration polarization effects, due to a selfcleaning mechanism induced by the centrifugal force that removes the concentration boundary layer over the membrane. Nevertheless, micro-TNF may outperform CNF in the fractionation of mixtures where a key solute has a MW close to the MWCO of the membrane. In this particular application, the micro-TNF allows an easier fractionating of the sample, because the key solute will exhibit a low rejection coefficient, due to the high polarization effects involved. Overall, both micro-TNF and CNF can be used to concentrate small volume samples, and the benefits and drawbacks of each technique are discussed in the paper.