Page 457 - Tandem Techniques
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the sample being generated by the chromatograph faster than the spectrometer can acquire the necessary
data from it. The sample cell must be small enough so as not to destroy the chromatographic resolution,
but still be large enough to contain sufficient sample to allow the spectrometer to acquire valid data in
the residence time available. To date, these two criteria have not yet been efficiently achieved. It is seen
in Figure 11.2, that the tandem system is basically a liquid chromatograph and a NMR spectrometer
joined by a valving system. The valving system is designed to allow any given peak to be passed to the
spectrometer or, if the spectrometer is acquiring data, to be stored in a sample loop until the
spectrometer is free. A diagram of the flow control and sampling unit is shown in Figure 11.3.
Figure 11.3
The Flow Control and Peak Sampling Unit for a LC/NMR System
