Rapid scanning stopped-flow detectors

Before any instrument can be used with confidence its operating characteristics must be well understood. The exceptional versatility of the vidicon rapid scanning stopped-flow system allowed a large variety of characterization experiments to be easily performed. A few of the more important experiments designed to help characterize the vidicon detector will be presented before the actual application of the instrument is discussed. 

Rapid-Mixing, Rapid-Scanning Stopped-Flow Systems 3.3.1. SINGLE ELEMENT DETECTOR SYSTEMS... 

These methods of obtaining complete ultraviolet-visible spectra can be very time-consuming. However, rapid scanning spectrophotometers based on optical diode array detectors are now eormnereially available and are capable of recording complete spectra in very short time intervals (1 second or less). They can therefore be used to obtain spectra of separated components without stopping eluent flow or to detect at several wavelengths simultaneously. 

Today a stopped-flow instrument consists of oifly the unit itself combined with a diode array detector and a computer allowing fast kinetic measurements of time-resolved UV-vis spectra under anaerobic, high pressure and/or low temperature conditions. Improvements have been made as well, for example, syringes are installed vertically instead of horizontally (to avoid problems with gas bubbles) and polyetheretherketone (PEEK) is used instead of Teflon for valves and flow tubes to improve the anaerobic capabilities of the instrument. Further, the syringe drives setup was optimized. Application of rapid-scan devices (usually, but not exclusively, diode arrays) allows complete spectra to be collected at very short time intervals during a reaction. 

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