Avoiding Double Peaks
In single stream manifold, (A), it is imperative to select the injected sample volume in such a way that a sufficient amount of reagent is available through the entire zone length to form a reaction product. While in FI single stream flow geometry is seldom used, it is the mode in which all SI systems operate (Chapter 2).
When the dispersion coefficient approaches 1 a double peak will be recorded since there is a lack of reagent in the center of the sample zone (B). To avoid this problem, the dispersion coefficient of a system should be determined and adjusted accordingly. This can be done either by injecting a smaller sample volume in SI system or in FI mode by using a two-stream system furnished with a confluence point. (1.2.15.)
1.2.8.
Reaction product (yellow) is formed at the interface between the sample (red) and the reagent (blue).
Injection of increasing sample volumes causes the formation of a double peak.
