User`s guide

Troubleshooting
367
trap filter disk, leading to poor recovery and peak
shapes as well as peak splitting.
Action: Replace the filter disks. See Changing the Trap
Filter Disks on page 281.
The Cold Trap Does Not Cool
Cause: The Peltier coolers have failed.
Action: Switch off the ATD/TD and contact your
PerkinElmer service engineer.
Cause: This effect is more likely to occur when a high
thermal conductivity carrier gas, such as helium or
hydrogen is used.
Action: Helium has a very high heat capacity (Thermal
Conductivity), which means that the trap may
not be able to cool to -30C at a high flow rate.
Use nitrogen as your carrier gas unless your
application specifically requires helium or
hydrogen.
Cause: The desorb flow is too high. If desorb flows in
excess of 100 mL/min are used with helium or
hydrogen as the carrier gas, the cold trap may not be
able to maintain its low temperature during primary
desorption.
Action: Use ultra dry air or nitrogen with a dew point of
-50°C or lower.
Action: If you must use helium or hydrogen, then
reduce the desorb flow rate.
Cause: There is a leak at one or more of the cold trap
connections.
Action: Check that all of the connections to the cold
trap and the heated valve are leak tight. Use a
50/50 water/alcohol mixture for leak checking,
leaks may open up at high temperature.
Cause: The trap is cracked or broken.
Action: Replace the cold trap as outlined Removing and
Replacing the Cold Trap on page 269.