Sample station modification providing on-line reagent addition and reduced sample transit time for flow cytometers.

A flow cytometer was equipped with a modified sample station to facilitate on-line addition of mediators to the sample and reduce the time of delivery of the sample to the interrogation point. The ready availability of materials and straightforward nature of this design make modifications simple and facilitate measurements of cellular activation. Parameters such as pH, membrane fluidity, and calcium mobilization are easily measured in this system, because detection can be made less than 4 s after addition of mediator with no interruption of sample flow. The sample station modification is described in detail along with methods for mixing and temperature control.