Skip to main content

NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

CHRNS: Stopped flow capabilities

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

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 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 seconds to ~400 ms. 

Accelerated Implementation for 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 

 

Contacts

Created February 4, 2023, Updated May 9, 2025
Was this page helpful?