You can prepare a program of levels (or "ramps"), executed in consecutive order, to control temperature during a run. The number of ramps available depends on your GC type. A ramped temperature program includes:
A constant temperature (or isothermal) program raises the temperature to a temperature Value before the run starts, then holds that temperature for the duration of the run.
A single ramp temperature program raises initial oven temperature to a specified final temperature at a specified rate, then holds at the final temperature for a specified period of time.
A multiple-ramp temperature program is similar. The oven or heater is programmed from an initial temperature to a final temperature, but with various rates, times, and temperatures in between. You may program multiple ramps for temperature decreases as well as increases.
Specify the following parameters for a ramped temperature program:
Rate — Rate (in °C/min) at which the GC heats or cools the oven or heater from Value on one program level to Value on the next program level. This constitutes a "temperature ramp". A rate of zero at any level disables the temperature program for that level and any which follow.
Value — The temperature (in °C) to which the GC heats or cools the oven or heater for a given program level. For isothermal (constant temperature) runs, set the Value parameter in the top row of the table to the desired temperature, then set the first Rate to 0.0 to disable any ramps. The initial Value is the temperature at the start of a run.
Hold time — The number of minutes the GC is to maintain a temperature Value for each given program level. The initial Hold time begins when you start the run:
If the initial Hold Time has a value of 0.00, and there are no ramp(s) defined, then an isothermal analysis is assumed using the default maximum run length of 999.99 minutes. Refer to To Create a Constant Temperature Oven Program for step-by-step instructions on preparing an isothermal program.
Run Time is a read-only display of cumulative run time through each ramp level.