An easy-to-build-timer for kinetic measurements in flow cytometry

Measuring kinetics of any time-dependent intracellular process on a cell-to-cell basis is a powerful extension of flow cytometry (FCM) possibilities. A digital timer is described that is easy to build and that fits with all commercial or custom made multiparameter equipment. Of all possible applications of this timer (phagocytosis kinetics, staining of cell components, enzyme reactions, etc.), one example is given: enzymatic intracellular precipitation owing to myeloperoxidase in human peripheral blood cells.