A New Micro Cryo-Trap for the Trapping of Volatiles at the Front of a GC Column


John Manura, Scientific Instrument Services

The new Micro GC Cryo-Trap was developed for the GC analysis of volatile and semi-volatile organics in gas samples with injection techniques such as headspace injection and thermal desorption. In both of these techniques large gas volumes are injected into the GC capillary column and the volatile organics are cryo trapped or cryo-focused on the front of the GC capillary column. Studies have proven that this trapping region can be as little as 1.0 inch in length. The Micro Cryo-Trap utilizes a 1.0" cooling chamber which surrounds the front of the GC capillary column inside the GC oven just under the injection port. Normally in order to cryo trap volatiles the entire GC oven is cyro-cooled using liquid CO2 at temperatures that cannot go below -40 deg C. With the new Micro GC Cryo-Trap, volatiles can be trapped at temperatures down to -70 deg C utilizing CO2 (or -180 deg C with LN2) using less than 3% of the cooling gas required to cool the entire GC oven. This results in more efficient trapping of the volatiles as well as substantial cost savings in CO2. To release the volatiles from the Cryo-Trap a heater coil inside the Cryo-Trap rapidly heats (up to 1000 degrees per minute) the capillary column to release the organics to produce well resolved GC peaks. This technique permits the analysis of volatiles in large gas injected volumes on capillary GC columns and improves the resolution of the analytes present in these samples. Applications of the Micro Cryo-Trap are demonstrated on samples introduced via the thermal desorption and headspace injection techniques.