CHRNS: Stopped flow capabilities

Principle

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 enables automated sample preparation on time scales matching those accessible to vSANS and CANDOR, and provides the time resolution necessary to characterize the kinetics of, for example, biocomplex formation.

The in-house-built stopped flow apparatus has improved its time resolution from ~3 seconds to ~400 ms. 

Implementation in FY-24

• Temperature-controlled (10-50 °C)
• 2 Syringe Pumps (for 2 sample injections)
• 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
• SECoP controlled with GUI and indicator panel (https://gitlab.nist.gov/gitlab/ces7/sfsans)
• Commercial cell (Biologic)
• Also available a commercial Biologic stopped flow system (SMF-4000, 30 ms deadtime, low viscosities)

Many thanks to the 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