FAQS - GC

Frequently Asked Questions


GC supplies

Is there a quick way that I can see all the supplies for my GC instrument?

Yes, please visit the GC and GCMS page to select supplies specific for your GC, such as autosampler syringes, ferrules, liners, and septa.


Inlet Liners

Can I clean my GC inlet liners?

We do not recommend cleaning inlet liners. All liners manufactured by Trajan are deactivated and certified for high performance. During cleaning the deactivation will be removed. Deactivating the cleaned liner in the laboratory will still result in the presence of active sites that can adsorb sample components and cause peak tailing, with potential loss of sensitivity and reproducibility.

How do I select the correct inlet liner for my analysis?

Download the Liner Selection Tool to assist in finding the right inlet liner for your analysis.

The tool also includes a handy Vapor Volume Calculator that checks if you are injecting too much for a particular liner. It can help you avoid the ghost peaks, injector contamination, and quantitation errors associated with flashback.


Ferrules

Can I use graphite ferrules on my mass spectrometer connection?

Graphite ferrules are porous to oxygen, therefore they are unsuitable for connecting columns to mass spectrometers.

Is 450°C really the maximum temperature for 100% graphite ferules?

The 450°C maximum is based on some oxygen being present. Above 450°C oxidation can start to occur. It can occur at lower temperatures if the ferrules are being used to seal a vacuum, as oxygen will be drawn in through the graphite. It may be possible to use them at 600°C without issues if oxygen has been excluded. Longer term there may still be some degradation.

What is the pressure rating for ferrules 072621 and 072622 100% graphite ferrules?

We rate these ferrules to 50 atm when used with our fittings.


SilTite

Can SilTite ferrules be used with Aluminium clad columns?

In-house testing shown that it is possible to get SilTites to work with Aluminium clad columns, but it is difficult to get them to work every time with a GCMS. If someone was not using MS, then if they are careful they should be able to get them to work.

Sometimes the Aluminium layer can be a little rough, so it would be a good idea to avoid any sections of the column that feel rough. Since the SilTite material is relatively hard, when it is compressed down on to a rough area of the Aluminium, it is more likely to cause a fracture.

Are there SilTite connections for the Thermo injector?

SilTite nuts and ferrules are only available for the MS interface.

Which SilTite kit should be used with the Thermo ISQ?

The Agilent MS SilTite kit can be used. The ferrule fits with the point into the nut.

Can SilTite ferrules be used with the normal nuts that I use with my graphite vespel ferrules?

No. SilTite ferrules can only be used with specific SilTite nuts which are characterised by two notches on the outside of the nut. The reason for this is that the angle in the tapered end of the nut is specifically designed to cause the tapered end of the ferrule to seal on the capillary column as the nut is tightened the required 60°. Swagelock type nuts don't have the correct angle on the taper to seal the ferrule on to the capillary column.

Which way does the SilTite ferrule go into the nut?

The ferrule is a back ferrule, which means that the tapered end of the ferrule goes into the tapered recess of the nut. This leaves the flat face of the ferrule to be in contact with the flat face of the interface providing an airtight seal.


SilTite FingerTite

The first dimension of our GCxGC system is stainless steel capillary column. Can I use SilTite μ-Union for column connection?

We have generally found that SilTite μ-Unions do not work well with metal columns. This is due to two factors.

One reason is that the outside diameter of stainless steel capillary columns is generally different to fused silica column with the same inside diameter. SilTite μ-Unions and ferrules rely on a very precise fit between the hole size and the outer diameter of the column. So when the outside diameter of the column is different, it is difficult to get a good seal.

The second reason is that the SilTite μ-Unions and ferrules rely on the polyimide outer layer of fused silica columns being slightly soft, so that they can crimp (swage) slightly into this layer. Stainless steel capillary column tend to be too hard, and if they are not quit round or slightly rough, then the SilTite μ-Unions and ferrules can not seal properly.


Septa

Do any of the current range of septa have a PTFE lining?

No.

What is the durometer rating of your septa?
  • GP Grade (blue): 47-57
  • HT Grade (red): 42-54
  • EC Grade (green): 45-57
  • MN Grade (pink): 40-52 
What is the thickness of your septa ?

Septa are 3 mm thick.

Are SEP0073 and SEP 0089 still available?

SEP0073 which were 3.2 mm thick, were replaced several years ago with SEP0089 which were the 4 mm thick. SEP0089 were then replaced a couple of years ago with part number 0418999. 0418999 is made of a different material (same BTO silicone as our HT septa), and looks different, but has been tested and approved by Los Gatos Research to replace SEP0089. It is isn’t pre-drilled, but does have a hole molded into to that goes part way through the septa. We don't list it on our website as it is thicker than the rest of our septa that are used in GCs, and would tend to cause problems if someone tried to use it in a GC.

Do septa contain phthalates that can contaminate my analysis?

Phthalates are seldom present in silicone parts. There are no phthalates added to the septa during the manufacturing process.


SilFlow

Tube insertion depth

The jigs are set so the length of the 0.4 and 0.5 tubing are a different length. The hole in the SilFlow is longer for the 0.4 mm than the 0.5 mm to reduce dead volume.

Our recommendation would be to set the ferrules in the SilFlow instead of using the jigs. This is just in case the tubing OD’s are different to expected.

The 1.1 mm tube must be swaged in the SilFlow. A wrench (spanner) may be needed to tighten enough to be leak free (part number 18500002 Spanner 3/16" x 1/4" AF).

What is the ID of the 1.1 mm OD tubing used for SilFlow (part number 123755)?

It is 0.65 mm ID.

Sticking ferrrules in SilFlow

When stainless steel and stainless steel (SilFlow and ferrule) are heated, there can be some minor sticking. To remove the ferrule easily push pin carefully around the outside of the ferrule to gradually release and remove it.

How do I remove pieces of column broken off in my SilFlow?

We recommend connecting to an HPLC pump and backflushing the SilFlow to remove any debris.

Can I put my SilFlow in an ultrasonic bath?

Yes, the SilFlow can be placed in an ultrasonic bath. The following solvents will not affect the deactivation:

  • Acetone
  • Methanol
  • Pentane
  • Dichloromethane / Methanol Chloride 
What temperature can I heat my SilFlow up to?

There is no practical temperature limit. The limitation will be the maximum temperature of the GC column.


Gas Purifiers

Can the Packed Column Moisture Trap (part number 103495 and 1034951) be regenerated?

No, these traps cannot be regenerated.

Where do I find MSDS for the current range of gas purifiers?

GAV-200

I am finding it difficult to get the sample bag out of the sampling canister. What should I do?

Ensure that the bag is not over inflated. Over inflation pushes the bag hard up against the walls of the canister, making it impossible to remove.

What are the GAV-200 gas sampling bags made of?

The GAV-200 sampling bags consist of three laminated layers; an inert polymer liner, an impervious aluminum layer to prevent diffusion of gases through the bag, and a tough polymer outer coating.

What pressures can be used with the GAV-200 sampling bags?

The sample bags are suitable for gas pressures differentials up to 5 psi.

What is the minimum and maximum temperature for the GAV-200 sampling bags?

Maximum temperature: 70°C
Minimum temperature: 5°C

What is the canister in the Gas and Vapor sampling kit made of?

The canister is polycarbonate and the cap is polypropylene.

What is the maximum pressure of the canister?

The maximum pressure of the canister is 50 psi.

How can I sample from a low pressure source?

When sampling from a low pressure source a vacuum can be applied to the canister.

What is the minimum and maximum temperature for the Gas and Vapor sampling kit?

Maximum operating temperature: 70°C
Minimum operating temperature: 5°C


Micro Control Valves

What is the Internal volume of MOVP part number 1236091?

The internal volume of valve 1236091 in the open position is 12.57 μL

My SMOV valve part number 1236282 has a PEEK seat. Is a vespel seat available?

Yes, this is part number 123681 VSV-6 Vespel Valve Seat pack of 5

How do I change the skirt seal (part number 0932163) on my valve?

The old seal has to be levered off. The new seal then has to be carefully levered on using something like a screwdriver, make sure that whatever is used doesn't have any sharp edges, or burrs, that might cut or tear the seal.

It may be tempting to use some detergent as a lubricant, but there is the risk that if any residue remains it may cause the valve to stick at a later stage. 


GC Columns

Can I use Hydrogen as the carrier gas with BPX70 columns at high temperatures?

At temperatures above about 220/230°C It is believed that the hydrogen carrier gas will chemically reduce the BPX70 phase (the opposite of what normally happens when oxygen gets into a column). This can be seen as a collection of small peaks towards the end on the run (at high temperature). These can easily be mistaken for trace levels of some of the longer chain fatty acids. When using helium, the peaks are no longer seen. Therefore it is not recommend to use hydrogen as a carrier gas with BPX70 phases at high temperatures.

What is the phase used for the CYDEX-B columns?

The CYDEX-B phase is 7% HEPTAKIS (2,3,6-TRI-O-METHYL) Beta CYCLODEXTRIN in a 14% Cyanopropylphenyl Polysiloxane.

What is the standard length of SilGuard guard columns?

5 meters.

Do you manufacture packed columns?

No.

How do I condition my capillary column before using it?

Each capillary column is factory conditioned and tested. It is recommended to give your column a short (30-60 minutes) conditioning before use. Further information can be found in the Capillary Column Installation Guide.

Do you supply bonded phases for your capillary columns?

All columns displayed on the website are premium low-bleed columns with bonded phases. This means that one is able to wash the columns with solvent.

Do you manufacture Porous Layer Open Tubular (PLOT) columns?

No.

Do you supply FAME standards?

We do not supply FAME standards, but there are a number of companies that do.

Why do my chromatogram peaks appear very broad?

Check the injection system first. If you are using split injection, ensure that your split flow is at least 20 mL/min. If you are using splitless injection, ensure your initial oven temperature is at or below the boiling point of the solvent.

I have a mass spectrometer in my laboratory, what capillary column should I use in this?

The best general purpose column is the BPX5 column. It has a 5% phenyl phase and the most versatile size is 30 meters x 0.25 mm ID with a 0.25 μm film (part number 054101). This column has been designed for mass spec applications and is especially low bleed.