Ultrafiltrace

Ultrafiltrace is a laboratory and process-analytic technique that combines ultrafiltration with tracer analysis to study the transport and retention of macromolecules and colloids in filtration systems. The method leverages size-based separation by ultrafiltration membranes and uses a tracer species—such as a fluorescent label, a radiolabel, or an isotopically enriched compound—to quantify passage through or retention by a membrane.

In typical workflow, a feed containing the tracer is circulated through a membrane module. Samples are taken from feed, permeate, and retentate streams and analyzed with appropriate detectors. By comparing tracer concentrations across streams and over time, researchers obtain retention coefficients, permeation fluxes, and information about fouling or concentration polarization. Ultrafiltrace can be implemented in both static batch tests and dynamic continuous systems, and it may be paired with complementary measurements such as permeate flux, transmembrane pressure, and dye-sorption studies.

Applications span water-treatment process characterization, pharmaceutical protein purification evaluation, and environmental studies of nanoparticle or natural organic matter transport. The method offers high sensitivity for trace-level species, rapid assessment, and the ability to discriminate size-based transport in complex matrices. However, successful use depends on tracer choice, as tracer-membrane interactions can bias results. Fouling, concentration polarization, and adsorption onto the membrane can complicate interpretation and require careful controls and calibration.

Ultrafiltrace is an area of active research and is not yet a standard method in routine membrane characterization. It complements conventional permeation tests by providing insight into trace transport phenomena under realistic operating conditions.