Plug flow cytometry: An automated coupling device for rapid sequential flow cytometric sample analysis

Background: The tools for high throughput flow cytometry have been limited in part because of the requirement that the samples must flow under pressure. We describe a simple system for sampling repetitively from an open vessel. Methods: Under computer control, the sample is loaded into a sample loop in a reciprocating eight-way valve by the action of a syringe. When the valve position is switched, the plug of sample in the sample loop is transported to the flow cytometer by a pressure-driven fluid Line. By coupling the plug-forming capability to a second multi-port valve, samples can be delivered sequentially from separate vessels. Results: The valve is able to deliver samples at rates ranging up to about 9 samples per minute. Each plug of sample has uniform delivery characteristics with a reproducible coefficient: of variation (CV). Even at the highest sampling rate, carryover between samples is limited. Conclusions: Plug-flow flow cytometry has the potential to automate the delivery of small samples from unpressurized sources at rates compatible with many screening and assay applications. Cytometry 37:156-159, 1999. (C) 1999 Wiley-Liss, Inc.