Autosamplers

The epsilon LC detector can communicate with autosamplers for automatic operation. Back-and-forth triggers are provided to start either instrument from the other. In addition, ChromGraph Control can read the vial position from an appropriately equipped BASi autosampler and save it, along with user-provided sample information, with the data for each run.

For successful automatic operation, you must ensure that the computer does not switch to an energy-saving mode. Please read the section on Setting Power-Management Options.

THREE WAYS TO COMMUNICATE
METHOD 1: epsilon IN CHARGE
METHOD 2: AUTOSAMPLER IN CHARGE
METHOD 3: FULL HANDSHAKE
IMPORTING SAMPLE INFORMATION FROM A .RAN FILE

THREE WAYS TO COMMUNICATE

There are three basic methods of coordinating injections with an autosampler. Each has its advantages and disadvantages. The three methods are:

METHOD 1. epsilon is in charge.
METHOD 2. Autosampler is in charge.
METHOD 3. Full handshake -- neither instrument can start without a trigger from the other

The advantages and disadvantages relate to how easy it is to hook up and troubleshoot the connection, and to the consequences if something goes wrong with your equipment. What can go wrong? What if a momentary power outage causes the computer to reset, but not the autosampler? What if you miscalculate and run out of mobile phase overnight? What if you put one vial in the wrong place and the autosampler stops with a 'missing vial' error?

The advantages and disadvantages of each method are as follows:

METHOD 1. Simple to connect and troubleshoot. If the chromatograph runs into trouble, the autosampler does not inject the remaining samples. If the autosampler runs into trouble, the chromatograph continues to make runs, but they are all blank.
METHOD 2. Simple to connect and troubleshoot. If the autosampler runs into trouble the chromatograph will stop making runs. But if the chromatograph runs into trouble the autosampler continues to inject until ALL THE SAMPLES ARE LOST.
METHOD 3. Complex to connect and troubleshoot. If either instrument runs into trouble, the other will stop making runs or injecting samples.

We recommend Method 1 for routine use, and Method 2 for the BASi Pollen-8 On-Line Injector.

METHOD 1: epsilon IN CHARGE

Method 1 can be used with any autosampler that will load a sample and wait for an inject trigger. This includes the BASi Sample Sentinel autosampler. Method 1 is a safe method of communication because the autosampler cannot inject the samples on its own.

Connect the Sample Sentinel autosampler to the epsilon system as described in the Installation section.

For a non-BAS autosampler, connect a two-wire cable from the START-OUT screw terminal and its ground on the rear panel of the epsilon detector:

The START-OUT connection provides a TTL-low at the start of each run. Connect the other end of the cable to the SAMPLE ENABLE terminals on the autosampler.

Program the autosampler so it will end its run and load the next sample before the epsilon system has completed its run (about a minute shorter than the epsilon system's maximum run length). Run length is the longest time of any of the following modules in the Method: Pump, EC Detector, External Detector, PAD, or Switch Schedule. Click here for a review of the Method modules.

The autosampler must be instructed to wait for an inject trigger before injecting. For the BASi Sample Sentinel, this is done as follows:

Select OPTIONS from the Main Menu

Select INPUT POLARITY from the Options Menu
- Change INJECT HOLD ACTIVE from LO to HI

Now program the epsilon system to run automatically. Set the Trigger Type to automatic in the Data Acquisitions section of the Method, and specify the number of runs:

Start the Method from the RUN STATUS box by clicking EQUIL, and then RUN:

The epsilon system will proceed automatically from one run to the next, and send a start signal to the autosampler each time. It is imperative that the autosampler end its previous run, load the next sample, and be in a 'hold' mode when the epsilon system sends the trigger.

METHOD 2: AUTOSAMPLER IN CHARGE

If the autosampler will not accept an inject trigger, then the autosampler must be in charge of the run. Use this approach for the BASi Pollen-8 On-Line Injector. One drawback here is that the autosampler will have no input from the chromatograph, so it will continue to inject samples if the chromatograph malfunctions.

To configure the system with the autosampler in charge, use a two-wire cable. Connect one end to the START-IN screw connector and its ground on the rear panel of the epsilon detector:

The START-IN connector accepts either a switch closure or a TTL-low signal. Connect the other end of the cable to the appropriate terminals on the autosampler. The autosampler's run must be about a minute longer than the maximum run length of the epsilon system, so the chromatograph is waiting for a trigger when the autosampler is ready to inject. Run length is the longest time of any of the following modules in the Method: Pump, EC Detector, External Detector, PAD, or Switch Schedule. Click here for a review of the Method modules.

Program the epsilon system to accept an external trigger in the Data Acquisition Options section of the Method, and set the number of runs as appropriate:

Start the system by clicking EQUIL and then RUN in the RUN STATUS box:

The message 'waiting for trigger' will appear. Then start the autosampler.

METHOD 3: FULL HANDSHAKE

The BASi Sample Sentinel autosampler is capable of two-way communication with the epsilon system. The autosampler will not inject the sample until the chromatograph is ready to start its run, and the chromatograph will not start its run until the autosampler is ready to inject. Samples are thus safeguarded in the event of mechanical failure or depletion of mobile phase.

Connect the Sample Sentinel autosampler to the epsilon system as described in the Installation section. Once this is done the two units must be programmed to accept signals from each other, as follows:

The epsilon system should be set to accept an External trigger in the Data Acquisition Options section of the Method, and the number of runs must be specified:

The epsilon system's run length should be about a minute shorter than the autosampler's. Run length is the longest time of any of the following modules in the Method: Pump, EC Detector, External Detector, PAD, or Switch Schedule. Click here for a review of the Method modules.

The Sample Sentinel must be set so that it waits for a signal from the epsilon system before injecting. Change INJECT HOLD ACTIVE to HI in the OPTIONS sections of its menu, as follows:

Select OPTIONS from the Main Menu

Select INPUT POLARITY from the Options Menu
- Change INJECT HOLD ACTIVE from LO to HI

For the timing to work properly, it is imperative that the epsilon system be in the 'waiting for trigger' mode when the Sample Sentinel injects. Therefore, you must start the epsilon system first by clicking EQUIL, then RUN, in the RUN STATUS box:

Then start the autosampler. The complete sequence is as follows:

epsilon system goes into 'waiting for trigger'.
Sample Sentinel loads the sample, goes into hold, and sends a trigger to the epsilon system.
epsilon system starts, sending a trigger to Sample Sentinel, which injects sample.
epsilon system ends its run before the Sample Sentinel, goes into 'waiting for trigger' for next run.
Sample Sentinel loads its next sample, signals epsilon system.

IMPORTING SAMPLE INFORMATION WITH A .RAN FILE

ChromGraph Control will take input from a text file with a .ran extension and save this information along with the data. This allows you to permanently associate sample information such as patient name with the data.

The positioning of information in this file is critical, so we recommend that you copy our template, TEMPLATE.RAN, from the BASi directory and rename it in your data directory. You can then edit it to add your own information.

It is important that the .ran file be in text format, so all characters and spaces have the same width. Use any text editor to make the modifications. Alternatively, Control will call Windows Notepad if you take the EDIT .RAN FILE option under the DATA menu:

ChromGraph ignores the first 10 rows and 15 columns of the .ran file, including the heading, where you can enter comments. Information about the samples begins in row 11, column 16. The following information MUST be found in the specified columns, left justified.

Run Number: (Columns 16-25) If you do not have the vial-position option that sends the vial number to Control, Control will examine this column at the start of each run. If a run number anywhere in this column matches the current run number, Control will incorporate the relevant sections of that line into the data file. (Including the vial number, which you should ensure is accurate.) You must configure SETUP OPTIONS under the Data menu as follows for this to work properly: check the 'Get vial # in .RAN file' option.

Vial Number: (Columns 26-35) If you do have the vial-position option, then Control will examine this column instead of the Run Number column, at the start of each run. If a vial number anywhere in this column matches the number being sent by the autosampler, Control will incorporate the relevant sections of that line into the data file. You must configure SETUP OPTIONS under the Data menu as follows for this to work properly: check the 'Binary Vial Numbers' option.

Volume: (Columns 36-45) These numbers allow ChromGraph Report to adjust the results for each sample to account for variable volumes or sample weights. If this is not the case, put a zero in this column.

If volume does differ among samples, you can enter the volume for each sample. You must also indicate this in Setup Options (see figure immediately above). See ChromGraph Report for information on how these volumes are used. If a volume is entered, Control will import it, and any text that follows it, into the Run Notes section of the data. This reduces the space available for Sample ID (see below) unless you move the ID's over so they follow the volumes, with one space between.

Sample ID (Columns 46-80) Unless variable volumes are used, these columns are imported into the Run Notes section of the data and are appropriate for appending identifying information about each sample.

The .ran file should be placed in the default data directory where the Method and data files reside. Then edit the Method to insert the name of the .ran file into the Run Notes section of DATA DESCRIPTION:

As each run is started, Control will import the relevant information from the matching line in the .ran file.

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