Professor Ji-Hwan Song and a joint research team at the Korea Research Institute of Standards and Science (KRISS) published a study identifying the size-dependent bias in particle concentration measurements that occurs in flow cytometry in the American Chemical Society (ACS) journal Analytical Chemistry.

The title of the paper is “Comparative Analysis of Sample Loop and Counting Bead–Based Methods for Size-Dependent Bias in Flow Cytometry,” and through multiphysics simulations, the research team quantitatively revealed that the concentration bias observed in the traditional counting bead method results from microfluidic differences inside the sample tube.

As a result of the study, it was confirmed that the relative effects of gravity, buoyancy, drag, and Brownian motion vary depending on particle size, and that this difference causes structural bias that leads to over-representation of large beads and under-sampling of small beads. The research team suggested that a quantitative injection-based (sample loop) measurement method was effective as an alternative to minimize bias.

This study provides a theoretical foundation for establishing an accurate concentration measurement system for particles, cells, and nanomaterials, and is expected to make an important contribution to the quantification and standardization of flow cytometry in the future.