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The orange juice was centrifuged and the supernatant liquid filtered. The filtrate was passed through a
Waters C18 Sep-Pak®, and the retained solutes eluted with acetonitrile. In this sample preparation
procedure, most of the flavenoids are retained but the simple sugars are not. A sample of the acetonitrile
extract was placed on a reverse phase column, and the separation developed using gradient elution. The
spectra (from 100 scans at 8 cm- resolution) of an early major peak and two of the later eluting minor
1
peaks are shown in Figure 8.19. It is seen that good spectra are obtained and the signal to noise is more
than adequate for reference spectra matching.
The LC/FTIR tandem instrument has not been used frequently in natural product assays, but this has
been almost entirely due to relatively poor sensitivity of the early instruments.
Figure 8.20
The Lab Connections, Inc. LC/IR Interface
System Alternative LC/FTIR Interfaces
Courtesy of Lab Connections Inc.
