Increasing sensitivity of the Ortho analytical cytofluorograph by modifying the fluid system

By adding Teflon tubing to the effluent line of the Ortho 50H analytical cytofluorograph, we were able to increase the sensitivity of fluorescence and scatter detection threefold without compromising resolution. By increasing sheath backpressure (resistance), the additional tubing increases particle residence time within the detection area and thereby increases the total photon emission density per particle. In addition, the longer, wider tubing dampens the stream-destabilizing effects of minor obstructions in or movement of the effluent line. This increase in sensitivity and stability is desirable in applications requiring detection of particles exhibiting low-level fluorescence.