A Stopped Flow System with Hydrodynamic Injection for Red Blood Cells Osmotic Fragility Test

Simple instrumentation and procedure with stopped flow system coupled to hydrodynamic injection and spectrophotometric detection were developed for automatic osmotic fragility test (OFT). OFT is a test for abnormal red blood cells based on the kinetics of their rupturing in a hypotonic saline solution. A portion of red cells was merged on-line with a hypotonic saline solution. They were mixed while flowing into the detector and were stopped for a short period for continuously monitoring the change of turbidity based on a transmission signal. In this work, a possible application of the system for screening of beta-thalassemia trait is demonstrated. Descriptions of instrumentation development and parameter optimization are presented. The system offers advantages over the conventional batch-wise OFT in terms of automation, precision, analysis time and sample volume.