Supplies and Services for Mass Spectrometers, Gas Chromatographs
and Liquid Chromatographs
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19 | Last Update: 01/31/00 |
By John J. Manura , Chris Baker & John Manos
INTRODUCTION
The Cryo-Trap consists of a small heating and cooling chamber which surrounds the front 5 inches of the GC capillary column. This unit is installed inside the GC column oven just under the GC injection port to permit the trapping of volatiles and semi-volatiles either on column or on a guard column in front of the capillary column. A separate digital dual temperature range controller permits the accurate temperature setting and regulation of both the heating and cooling temperatures of the GC Cryo-Trap. The system can be used either manually to switch between the cooling and heating cycles or can be operated automatically via an input signal from a controlling device such as the S.I.S. Short Path Thermal Desorption System or GC signal switch. This new GC Cryo-Trap was originally designed for use in conjunction with the S.I.S. Short Path Thermal Desorption System, but has additional applications such as GC headspace analysis as will be demonstrated. Normally in order to cryo trap volatiles at the head of the GC column, the entire GC oven is cryo cooled using liquid C02 at temperatures that cannot go below -40 degrees C. With the new GC Cryo-Trap, volatiles can be trapped at temperatures down to -70 degrees C at the head of the GC column using less than CO2 of the C02 required to cool the entire GC oven. This results in more efficient trapping of the volatiles on column as well as substantial cost savings in C02. To release the volatiles from the Cryo-Trap, a heater coil inside the Cryo-Trap rapidly heats the capillary column to temperatures up to 400 degrees C. The released organics are subsequently temperature programmed through the GC column.
