Calibration-free method to determine the size and hemoglobin concentration of individual red blood cells from light scattering.

At present, hemoglobin concentration and the volume of an erythrocyte can be determined from the intensities of light scattered by an individual cell at fixed angular intervals. This method is used in modern hemoglobin analyzers, but it requires calibration of optical and electronic units by certified particles of known size and refractive index. We describe a method that is based on the parametric solution of an inverse light-scattering problem and does not require a calibration procedure.

Absolute real-time measurement of particle size distribution with the flying light-scattering indicatrix method.

The flying light-scattering indicatrix (FLSI, angular dependency of the intensity of light scattered by a moving individual particle) method, based on a scanning flow cytometer (SFC) that permits measurement of individual particle characteristics from light-scattering data, has been used for the determination of size distribution of the following particles: polystyrene latex, milk fat, and spores (Penicillium levitum, Aspergillus pseudoglaucus). The optical system of the SPC and empirical equations provided absolute sizing at the rate of 50 particles/s. Size distributions obtained with the FLSI method and a best-fit procedure using Mie scattering theory have been compared.