GC Control
Injecting Two GC Samples Simultaneously (7673 and 7683 Autosamplers)

To double the sample throughput, the Agilent 7673 and 7683 GC autosamplers support dual injection, allowing you to simultaneously inject two samples from different sample positions.

 Note:

The Dionex AS and AS50 autosamplers also support simultaneous injection of samples. Refer to Practical Tips for Device Control: Autosampler Control Autosampler Commands (AS/AS50).

Use the following command to enable or disable dual injection:

If DualInject is set to On, both injectors inject simultaneously. The master injector is always the injector mentioned in the Inject command. For example, the front injector is the master injector if the command is:

The master injector injects from the sample position defined in the sequence. The sample position for the other injector (the slave injector) needs to be defined separately, via either the Fixed Offset or the UDC method.

Fixed Offset Method

The Fixed Offset method defines the sample position from which to inject, relative to the position from which the Master Injector injects:

Dionex recommends reserving the first and third quadrants for the Front Injector and the second and fourth quadrants for the Rear Injector.

To run a chromatogram with one sample only, use a different PGM File including "DualInject = Off" for the corresponding sample.

UDC Method

For the UDC method, a User-Defined Column is required for the datasource named; for example, RearPosition, Value type "Integer", Minimum "1", Maximum "100." The "empty values are possible" option should be enabled. In this column, enter the sample position from which the slave injector (in this case, the Rear Injector) will inject.

The corresponding program lines read as follows:

Use the UDC method to define a separate sample position for each injection. If the Rear Injector will not be performing an injection, leave the corresponding cell empty. (This is only possible if the "empty values are possible" option is enabled for the column.)

For information about how to install the Dual Inject option for the 7673 and 7683 autosamplers, refer to Installation Instructions  Agilent 7673 and 7683 Autosamplers: Dual Inject in the Administrator Help section.

For information about how to install the autosampler, refer to  Agilent GC Autosamplers: Flow Chart in the Administrator Help section.