Dual absorbance/fluorescence spectrometer.

Stopped-flow systems have now reached dead time specifications well below one millisecond. There is, therefore, a need for detectors able to measure the signal on a microsecond time scale and with the highest signal to noise possible in order to save precious samples. Fluorescence and absorbance changes have been the most popular detection modes in rapid kinetics because these techniques are usually easy to set-up and are also highly sensitive.

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Modern spectrometers now use a single detector for absorbance and fluorescence measurements. The detection is made using a high-sensitivity photomultiplier tube (PMT) optimized for the full wavelength range of the spectrometer. The switch from absorbance to fluorescence is made in a few seconds. A second detector is available as an option for simultaneous absorbance/fluorescence measurements, or to extend the detection range to FRET fluorescence, dual fluorescence or T-format anisotropy.

 

Speed and sensitivity.

The MOS-200 is a simple, fast and sensitive rapid kinetics spectrometer. With its minimum 10µs time resolution and nM sensitivity, it is the ideal instrument for stopped-flow studies. Multi-time base acquisition modes are available so complex reactions with different steps can be followed easily. A motorized monochromator version (MOS-200/M) also exists for excitation scanning and multi-wavelength experiments, and its double light source allows the user to switch from steady-state to rapid kinetics almost instantaneously.