Setting Up the Autosampler Tray

When you use the Autosampler to automate sample loading and unloading, you must create a sequence of runs for each tray of samples.

There are several things to consider when you set up the sample tray.

Select from the following topics for more information:

• What is the maximum number of runs per tray?

• Can a pan be reused?

• In what order should the samples be placed in the tray?

• Calibrating the Autosampler

• Running an Autosampler as a Non-Autosampler

Maximum Number of Runs

 When you set up your tray, you must consider the maximum number of runs that can be set up in a run sequence. The number of runs is dependent upon several factors.

• The maximum number of sample positions in the sample tray is 50, along with 5 reference positions.

• If you use the LNCS for cooling experiments, the number of cooling runs that can be performed in a run sequence is limited by the amount of liquid nitrogen in the tank. The rate at which liquid nitrogen is used up depends, of course, on your procedure:  the temperature you use, how long you hold the cell at a particular temperature, the rate of change in temperature, and so on. In general you can expect to get approximately 10 to 15 cooling runs with one full LNCS tank of liquid nitrogen when your procedure cools to the lower limits of -150°C.

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Reuse of Pans

Because thermal analysis experiments can sometimes deform the pans or cause the sample material to boil out, we do not recommend that you reload pans in the Autosampler once they have been unloaded from the cell. If you want to run a sample through more than one thermal procedure during your run sequence, do one of the following:

1. Run several methods consecutively on one sample pan. The Autosampler does not unload a pan at the completion of a run if the next run calls for the same pan.

2. If you prefer not to run consecutive methods on one sample, prepare several pans containing the same material.

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Order of Runs

To avoid mistakes, we suggest that you place the pans in the sample tray in the order in which you intend to run them. The following paragraphs suggest some guidelines for determining the order of your runs.

Perform cooling methods before heating methods.

Unlike the electricity that supplies the cell heater, the LNCS's supply of liquid nitrogen is limited. Therefore, it is a good idea to keep the amount of liquid nitrogen needed to do a cooling procedure at a minimum by putting all cooling-only runs at the beginning of an Autosampler run sequence. If you plan to run combination cooling/heating procedures, these experiments should come next, followed finally by any heating-only procedures.

Keep runs of a similar procedure together.

For example, if you plan to run some of your samples through a cooling procedure and some through a heating procedure, you should run all of the cooled samples consecutively to prevent unnecessary waste of your liquid nitrogen supply. If you alternate heating and cooling runs, the heater will have to work harder to bring the cell up to temperature and the cooling accessory will have to work harder to bring the temperature down again.

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