Olson, R. J.. Woods Hole Oceanographic Institution, rolson@whoi.edu
Sosik, H. J.. Woods Hole Oceanographic Institution, hsosik@whoi.edu

 
AN IN SITU FLOW CYTOMETER FOR THE OPTICAL ANALYSIS OF INDIVIDUAL PARTICLES IN SEAWATER
 
Flow cytometry has proved a valuable tool for the analysis of phytoplankton and other suspended particles because of its speed and quantitative measurements, but the method's oceanographic application has been limited by the need to take discrete water samples for analysis on board ship or in the laboratory. For this reason, we have developed an in situ flow cytometer, which can operate unattended. This instrument differs from conventional flow cytometers in that it uses a simple ducted flow of seawater through the flow cell, rather than hydrodynamically focussing a stream of sample seawater by injecting it into a sheath of particle-free fluid. The new instrument defines a sensing region in the center of a diode-pumped 532 nm laser beam, based on the intersection of 2 diode lasers; only signals from those particles which pass through all 3 beams are accepted. This approach should be less susceptible than conventional flow cytometry to problems stemming from flow disturbances, and hence more amenable to unattended long-term operation. Tests in the laboratory and off the WHOI dock indicate that sensitivity is comparable to that of conventional flow cytometers. Design details and initial results will be presented.
 
Day: Tuesday, Feb. 2
Time: Poster
Location: Sweeney Center
 
Code: SS41TU0538S