Capillary Chromatography - Injection Systems 1



Injection Systems


Due to the small dimensions of the column, a very small mass must be injected and this must take the form of a very sharp band of solute entering the column. There are a number of different injection devices that can be used and the appropriate form will depend on the dimensions of the capillary column, in particular its internal diameter. For columns that have diameters that preclude the entry of a syringe needle, a split injector must be used, a diagram of which is shown in figure 6.


The sample is injected into the hot liner where it is vaporized into a gas stream flowing at (Q) ml/min. It is seen that the capillary column projects into the glass liner and the carrier gas sweeps past the column inlet and out to waste. As the vapor passes down the injector body it splits into two streams some entering the column at a flow rate of (q) ml/min. and the remainder passes out of the system to waste at a flow rate of (Q-q) ml/min.



Figure 6. Split Injection System