Abstract
A new flow through instrument that simultaneously measures cell volume (resistance pulse technique) and cell fluorescence in the same orifice will be described. The fluorescence pulses of the hydrodynamically focussed cells are picked up by the optics via the axial direction (principle of Dittrich and Goehde, Z Naturforsch 24b:360, 1969). There is no coordination problem between the fluorescence and the resistance pulses to be observed because a new type of transducer is used. The electronic system provides gating of one or two parameter histograms. Function tests are performed with the incorporated two-parameter test spectrum generator. Different examples of using the instrument in practice are shown. The volume that may be measured with an orifice of 70 micron diameter ranges between 4 and 1400 micron3 (1:350). Coefficients of variation of the fluorescence below 2% are measured.