GC Control
Injecting Two GC Samples Simultaneously (6890)

To double the sample throughput, the 6890 GC supports the dual-operation mode, which lets you simultaneously inject two samples from different positions. The following conditions must be met:

• The GC must be fitted with the required hardware components.

• The GC must be installed in two timebases (refer to Hardware Installation: Third-Party Devices  Agilent 6890 GC: Dual Operation in the Administrator Help section).

• The PGM Files for the two timebases must match.

• A batch must be available for each timebase.

After installing the GC, follow the steps below to set up the dual-operation mode.

Creating two PGM Files

Create a PGM File for each timebase, observing the following:

• Enable dual operation with the following command (this can be done only from the control panel):

• DualOperation

  = Shared

   

• Enable dual operation for the related sample(s) (this can be done from the control panel, also):

• Sharable

  = ON

   

   Tip: 

  When a batch is running, you cannot perform manual commands in the Shared mode (exceptions: RunLog, ReportReady, and PrepRun). To control the GC via manual commands while a batch is running, assign the GC to only one timebase:

  DualOperation

  = FrontOnly or BackOnly

   

• Make sure that all commands and properties shared by the timebases (see  Commands and Properties for Dual Operation (6890)) have the same values at the same retention times. This is especially important for the temperature. If the values and/or retention times are different, the samples will be processed one after the other.

   Note: 

  The ReadyCheck cannot always establish exactly in which order the samples are processed. Therefore, more or less warnings than appropriate may appear during the ReadyCheck.

• In general, commands and properties that are assigned to only one timebase can be set independently of the setting in the PGM File for the other timebase. The Inject command is an exception: It must be available in both programs at the same time. (In special cases, it may be missing in both programs; it must not be missing in only one program.)

Creating a sequence and a batch for each timebase

It is not possible to simultaneously inject two samples from the same vial (except if UseTray = No).

The batches do not have to include the same number of samples. If all samples of one batch are processed, sample processing will continue for the remaining samples of the other batch.

 Tip: 

You can add new samples or sequences to the finished batch and restart the batch. Sample processing is resumed when the next sample of the running batch is started.

Starting batches

In dual operation mode, a batch must be started on both timebases simultaneously:

• Create the two batches and perform the Ready Check on both timebases. Afterward, start the two batches.

  A message may appear in the Audit Trail telling you to start a batch on the other timebase, too.

• Start the batch on the other timebase.

  The two batches run in synchronization. The Ready Check checks that the shared properties, temperature gradient, and run time for the sample pairs match and that the injections are performed from different positions.

   Note: 

  Observe the following restrictions:

  The Ready Check can check only the active sequences.

  The Ready Check can detect changes to the running sequence on the other timebase only when you stop and restart the batch on the other timebase. If the Ready Check reports an error on the other timebase, follow the steps below.

  - In the timebase for which the error was reported:

  - Stop the batch.

  - Eliminate the error.

  - For the first sample, change the status from Interrupted to Single, if necessary.

  - Restart the batch.

  - Return to the original timebase.

  - Run the Ready Check again.

   

Examples

a) To analyze a pair of sequences (e.g., Front1 and Back1) simultaneously on two timebases (e.g., Front and Back) and then run another sequence (Front2) only on the Front timebase:

• For the pair of sequences, set Sharable = On.

• In the PGM File for the Front2 sequence, set Sharable = Off.

b) Use the following settings if you want to process samples in dual operation mode whenever possible but also analyze them one after the other if required:

• Accept the default setting: DualOperation = Shared, however

• Do not enter the Sharable command in the PGM File.

c) If you want to run a batch only on one timebase (e.g., on the Front timebase), select one of the following alternatives:

• In the PGM File, set Sharable = Off and start the batch on the Front timebase.

--Or--

• On the control panel, set DualOperation = FrontOnly and start the batch on the Front timebase.

In both cases, the batch is started immediately and does not wait for a batch on the Back timebase.

For information about how to install the 6890, refer to  Agilent 6890 GC: Installation.