Thermo Scientific TSQ 8000, User Manual

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Changing the Column
Replacing the Factory Installed Column
16 TSQ 8000 Evo User Guide Thermo Scientific
• Internal Diameter —The smaller the diameter of the column, the better the separation.
However, smaller diameter columns do not have as much capacity for matrix or analytes.
As a result, smaller diameter columns are subject to overloading, which leads to retention
time shifts and peak shape changes. Larger diameter columns can accept larger
concentrations of material, but will require longer columns or slower GC oven
temperature ramps (which increase the analysis time) to match the separation power of
smaller-diameter columns. Typical column sizes for GC/MS have inside diameters (ID)
of 0.25 mm. Smaller ID columns, such as the 0.18 and 0.10 mm, are becoming
increasingly popular. Additionally, 0.32 and 0.53 mm ID columns are commonly used.
• Film Thickness —With larger film thicknesses, there is more capacity for the analyte.
This capacity can aid in the separation of high concentration samples and in the
separation of very volatile samples because thicker stationary phases allow more
opportunities for the analytes to interact with the stationary phase. The optimal film
thickness depends on the internal diameter of the column, and the maximum total
capacity needed for sample analysis.
Thick films with small internal diameters give very strong interactions with the analytes,
which can result in longer analysis time and peak tailing. Large ID columns with thin
films have very little interaction with the analytes, which will result in very fast analysis
times with little separation. Typical film thicknesses are 0.25 μm for a column with an ID
of 0.25 mm. Other common film thicknesses are 0.1, 0.5, and 1.0 μm.
Be careful when selecting columns for mass spectrometers. Some columns with large
inner diameters that work fine with other GC detectors may need lower head pressure
when operated with vacuum at the outlet. This lower head pressure can allow air diffusion
into the column through the carrier gas flow module's split and purge valves.
• Length —The length of the column affects how much time the analyte has to interact
with the stationary phase. Longer columns typically have better resolutions and higher
capacities, but longer analysis times. Longer columns are also more expensive. Typical
column lengths are 15 or 30 m for GC/MS, but 100 m columns may be needed for very
complex mixtures like gasoline. Very short columns (2.5, 5, and 10 m) are also available.
Replacing the Factory Installed Column
 To replace the factory-installed column in the TSQ 8000 Evo system
1. Cool down the GC oven and injector. See the GC documentation for information.
2. Open the TSQ Series Dashboard and click Shut Down .
Note Contact your local sales representative to order a Thermo Scientific column. You
can also refer to our catalog or visit our Web site at www.thermoscientific.com/columns .
Note If you are running samples, stop the acquisition before powering off the system.