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CHRNS: Stopped flow capabilities

Image of a stopped flow device, ancillary equipment and schematic of a potential experiment


In this device solutions are forced into a specially designed mixing chamber. After a time, perhaps as short as a few ms, the solution is pushed into the sample cell at a time recorded using the master clock. Thus, this device will allow automated sample preparation to be done on a time scale matching those accessible to vSANS and CANDOR and provide the time resolution necessary to characterize the kinetics of, for example, the formation of biocomplexes.

The in-house-built stopped flow apparatus has improved its time resolution from ~3 second to about 1 second with a remaining goal of reaching ~400 ms. This benchmark should be achievable once we receive the high-pressure neutron scattering cell that was procured with the commercial stopped-flow system (eta Feb 2023). 

Current status (accelerated for 22-24)

  • Temperature-controlled (10-50 °C)
  • 2 Syringe Pumps (for sample injection)
  • Pressure sensors – automatic overpressure shutdown
  • Selector valves for fluid path control
  • High-speed mixer
  • 2 sample cells 
  • 2 Pressurized lines for solvent rinses & drying
  • UV-Vis spectrometer (multi-modal data, NEW for FY23)
  • Dead Volume: ~ .75 mL
  • Dead Time: ~ 400 ms (NEW for FY23)
  • SECoP controlled with GUI and indicator panel (
  • Commercial cell (Biologic)
  • Also available a commercial Biologic stopped flow system (SMF-4000, 30 ms deadtime, low viscosities)
Many thanks to party of interested scientists that provided feedback and prioritized capabilities:

Lilo Pozzo – Washington; Ron Jones – NIST; Norm Wagner – Delaware; Drew Marquardt– Windsor;  Sarah Rodgers–RAL; Adrian Rennie– Uppsala  Andy Church–RAL;  Lionel Porcar– ILL 



Created February 4, 2023, Updated May 6, 2024