Perhaps the most frequently used rapid kinetics techniques is stopped-flow. Small volumes of solutions are rapidly driven from syringes into a high efficiency mixer to initiate a fast reaction. The resultant reaction volume then displaces the contents of an observation cell thus filling it with freshly mixed reagents. The volume injected is limited by the stop syringe which provides the “stopped-flow”. Just prior to stopping, a steady state flow is achieved. The solution entering the flow cell is only milliseconds old. The age of this reaction volume is also known as the dead time of the stopped-flow system. As the solution fills the stopping syringe, the plunger hits a block, causing the flow to be stopped instantaneously. Using appropriate techniques, the kinetics of the reaction can be measured in the cell. - See more at: http://www.hi-techsci.com/techniques/stoppedflow/#sthash.taXnRjE9.dpuf