Effects of ageing on preserved red blood cell populations as measured by light scattering.

Instability of reference materials may cause problems in interpreting results for assurance of quality in haemocytometry. The stability with time for a certain preserved blood specimen is also highly dependent on the principle of measurement. In this paper some effects of ageing on red cell populations in commercially available (Ortho) Blood Controls are evaluated. Red blood cell size histograms become narrower while mean corpuscular volumes obviously decrease with time when measurements are based on light scattering intensity. In contrast, monodisperse polystyrene spheres of different sizes show perfect stability at storage. Such artificially prepared controls should be applied to achieve optimal setting and calibration of haematology analysers.