[Detection of reagent errors by internal quality control of the Coulter counter S].

By a simple program of quality control for the Coulter counter model S two deficient reagents could be detected. To high values of PCV associated with a decrease of MCHC were caused by a faulty Isoton batch. This error was revealed by native blood samples but not by the stabilized 4 C standard. Falsely elevated leukocyte counts due to insufficiently lysed giant platelets and platelet aggregates were produced by modified Lyse-S batches. Comparisons made with a Coulter counter model F using Zaponin and with a counting chamber yielded values at lower levels.