Theory of Operation and Description

New Programmable Cyro-cooling and heating trap for the Cryo-focusing of volatiles and semivolatiles at the head of GC capillary columns.

The Cryo-Trap consists of a small heating/cooling chamber which is 3/4" in diameter and 5" long which mounts to the bottom of the GC injection port just inside the GC oven. In the center of the chamber is a small stainless steel capillary through which the capillary column freely passes. Capillary columns up to megabore (0.53mm I.D.) diameters can be used. Around the stainless steel capillary tube a heating coil is wound to provide for the rapid heating of the capillary tube. A thermocouple provides accurate measurement of both the cooling and heating temperatures. Either Liquid C02 (Model 951) or Liquid Nitrogen (Model 961) for cooling is introduced into the Cryo-Trap (Cooling Gas In), and is exhausted through the outlet (Gas Out). The exhaust can either be vented into the GC Oven or a tube can be attached to vent the cooling gas external to the GC.

The control of the Cryo-Trap is provided via an independent Cryo-Trap Controller provided with the system. Both the Cryo-Cooling and heating temperatures are set via this digital temperature controller. The system can be used either manually to switch between cooling and healing or can be operated automatically via an input signal from a controlling device.

For the cooling operation the cooling gas is pulsed into the chamber. Liquid CO2 (Model 951) will cool down to -70 degrees C. Liquid Nitrogen (Model 961) will cool down to -180 deg. C. The cooling temperature can be set to any temperature between room temperature and the lower limits of the cooling gas. The temperature controller will pulse the cooling gas into the chamber to accurately control the temperature to the value you set. The thermocouple provides the feedback to both regulate the temperature as well as display the GC Cryo-Trap temperature on the display of the temperature controller. The electronics of the Model 951 and Model 961 are different due to the different cooling properties of the liquid CO2 and Liquid Nitrogen. Also the Cryo-Traps themselves are different for both models. Therefore parts are not interchangeable between the two models and the particular model can only be used with the cooling gas for which it was designed.

Each GC Cryo-Trap System consists of the GC Cryo Trap itself which goes inside the GC oven as well as the Dual temperature controller. When ordering it is also necessary to purchase a GC Cryo-Trap installation package to fit you particular model of GC. See the Ordering Information page for details.

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