Question

Exercise 17.15. List and describe the three common methods of sample injection in CE.

Answer 1

The way in which the analysis is injected into the CE is very different from the way HPLC.
HPLC is injected in constant volume and "injected" into the running phone stage after activation of the injection valve. Because CE is performed on small blood vessels with an internal diameter of 50–100 µm, and separation is performed with voltage injection, the method of incorporation in HPLC is not commonly used.
In contrast, an injection of “hydrodynamic” or “electrocardiogram” was used to place a small sample at the beginning of the artery. In both cases, the capillary was removed from a split electrode to a sample, the sample is injected and then the blood vessel is inserted into a separate electrode and voltage is applied. While both approaches insert the sample into small blood vessels, they do it in different ways.
With the injection of the sample hydrodynamics due to pressure differences between the entrance and exit of the plate. This can be done by applying positive pressure to the entrance, negative pressure to the exit, or as done at the beginning of CE. White by raising the von Inn to a certain level around the outgoing pot to collect the Siphon in the sample
capillary. While this last method looks pretty rough replicable and easier to perform than just a click vacuum cleaner. However, due to height differences, it is only about 10 cm
The pressure generated is low, which means it is useful for minimal injection low viscosity electrode and not suitable for use in high viscosity separations electrolytes, like those, break down the size of nucleic acids and proteins. This may explain why it is not used in most commercial devices that are found today.
Hydrodynamic injection is usually limited to about 1-3% of the capillary volume larger injections lead to an increase in the peak dispersion due to the different electron flow in the sample and the electrolyte separation.