Kinetic measurements via
Stopped Flow apparatus

CERM - UniFi - Firenze


The growing interest of scientifical and pharmaceutical communities in the field of biological reactions, has led to the improvement of stopped-flow mixing system that is capable of measuring rapid kinetic reactions with a timescale in the range of 0.5 ms to minutes. The SFM-4000 stopped-flow is available for a wide range of applications, e.g protein folding/refolding, protein-protein interactions, fluorescence resonance energy transfer (FRET), ligand binding, water and ion transport in vesicles and membranes, enzyme/substrate reactions, coordination reactions in inorganic chemistry, as well as identification or capture of intermediates, and more. Moreover, some time point samples for EPR, NMR, Mossbauer or GC/MS analysis can be collected if chemical quench or freeze quench accessories are coupled with stopped-flow mixers. With the SFM-4000 stopped-flow technology, it is possible to do kinetics with a rate constant up to 3500 s with the shortest possible dead time (around 700 µs and 200 µs using optional microcuvette for the most demanding applications), the highest precision and to minimize sample consumption as much as possible.


The SFM-4000 stopped-flow is a versatile instrument useful to a wide variety of rapid mixing techniques and applications, consisting of mixing device coupled to a detection system. In SFM-4000 stopped-flow system several modes can be used to run experiments, from optical stopped-flow to chemical quench-flow, to freeze quench, and to cryo stopped-flow (with temperature range from -25 °C to 120 °C). A maximum of four sample solutions are rapidly mixed, injected into an observation cell and the kinetics are recorded when the flow is stopped. SFM-4000 stopped flow system presents an independent stepping motor technology that confers it the possibility to change the mixing ratios and provides microliter precision and accuracy at all flow rates, over a wide viscosity, temperature, and mixing ratio range. Moreover, Berger-Ball technology mixers can be used to provide the best turbulent mixing over the widest range of flow conditions.