Quick-Thread Centrifugal Membrane Filter (QuT-CMF) for concentrating small-volume samples by nanofiltration/reverse osmosis

• QuT-CMF concentrates low MW solutes in small-vol. samples by NF/RO via centrifugation. • Salt/sugar solutions of 0.1–6 bar osmotic pressures were concentrated up to 22-fold. • Two piston designs, floating (FP) and sinking (SP), were tested to aid concentration. • The FP provided a more efficient concentration of high osmotic pressure solutions. • QuT-CMF design allows easy reuse with various membranes for multiple applications. Concentrating low molecular weight (MW) solutes in small-volume samples is essential in many analytical and research applications. A straightforward and reliable method is required to efficiently concentrate different types of solutions, while minimizing solute losses and complying with quality demands. The Quick-Thread Centrifugal Membrane Filter (QuT-CMF) was developed and tested to concentrate small-volume samples (4 mL) of low MW solutes. The QuT-CMF ensures easy assembly/ disassembly and membrane replacement, being capable to accommodate a broad variety of membranes with small area (2.4 cm 2 ) for several applications. A piston was used to maintain consistent high transmembrane pressure throughout the concentration process. Two different designs were tested: a sinking piston (SP), establishing a fixed concentrate volume, and a floating piston (FP), generating a dynamic concentrate volume. Using both pistons, the capability of QuT-CMF to concentrate MgSO 4 and xylose solutions, with different osmotic pressures (0.1–6 bar), was studied and validated, using nanofiltration (NFS, Synder Filtration, USA) and reverse osmosis (DairyRO-3838-46, Hydranautics, USA) membranes. While both pistons exhibited comparable performances in concentrating low osmotic pressure solutions (0.1–2 bar), achieving up to 22-fold concentration, FP outperformed SP for high osmotic pressure solutions (4–6 bar), as it minimized concentration polarization and adsorption, thereby reaching higher concentration factors and permeation fluxes, along with reduced permeability (loss) of solutes. QuT-CMF thus offers an efficient, user-friendly, and reusable option for concentrating low MW solutes, with versatility across distinct membrane separation processes.