- The capillary
inlet system is designed for capillary columns. The volume that can
be injected into the column is limited to approximately 2 microliters
(µL) and typically is used for pesticide and PCB analysis. The system
has less column bleed and retention time shift.
- The packed
inlet system is designed mainly for packed, wide-bore columns. However,
an adapter can be used to enable capillary columns to be used. The system
is used mainly for volatile analysis using a headspace extraction technique
and allows a larger volume of gas to be loaded onto the GC for analysis.
- The split
technique is the most common. The column flow is split at the injector.
The technique is used for high concentration samples.
- The splitless
technique is used for trace level analysis.
- The on-column
technique does not involve vaporization, but instead the sample is deposited
directly into the column with a syringe. This technique provides the
optimum in capillary column performance by eliminating discrimination
and degradation effects that can result from using a vaporization technique.
The technique is well suited for high boiling point compounds.
column injectors that have been converted to accept megabore capillary
columns (0.45 and 0.53 millimeter inner diameter) are very simple and
relatively trouble free. Larger volume injections of up to 6 µL can be