Frequently asked questions (FAQs)
GC supplies
GC inlet liners
- ◄What is a GC inlet liner? What is the purpose of an inlet liner?
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A GC inlet liner is typically a borosilicate glass tube providing a sample path through the injection port (inlet) to the GC column.
The inlet liner assists with sample vaporization by the inlet liner geometry and packing material increasing heated surface area; sample protection via chemically deactivated borosilicate glass; and column protection from nonvolatile sample contaminants with inlet liner packing material such as quartz wool or glass frits, trapping non-volatile sample components and preventing them from entering the column.
- ◄What’s the difference between standard SGE® inlet liners and SGE OptChem™ inlet liners?
- ◄Why should I use inlet liners which are pre-packed with quartz wool, rather than packing it myself?
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While self-installing quartz wool into an inlet liner, it is difficult to completely avoid breakage of the wool fibers. Broken fibers will increase chemically active sites within the inlet liner and can also scratch the interior surface of the inlet liner, causing further activity issues.
SGE inlet liners are deactivated after wool insertion to ensure any active sites exposed are rendered inert. This increases the reproducibility of the analysis.
- ◄Can I send used/dirty liners back to Trajan for cleaning and/or redeactivation?
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No, Trajan does not offer this service. For best results, Trajan recommends that used/dirty liners to be discarded and replaced with new liners.
- ◄What does “inlet liner geometry” refer to? How does it affect inlet liner performance?
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Various geometry and quartz wool options in the SGE inlet liner range allows the user to select the optimal liner choice for their specific application.
The SGE inlet liner range is color coded by geometry, making it easy to choose the inlet liner you need.
- ◄Can I clean my GC inlet liners?
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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.
- ◄Are SGE OptChem inlet liners compatible with the same injection solvents as SGE standard inlet liners?
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As a general rule, if the solvent is not harmful to the GC column, then it will also not harm the inlet liner. This is true for both SGE OptChem and SGE standard inlet liners.
- ◄How do I select the correct inlet liner for my analysis?
- ◄How can I avoid loss of high boiling point compounds?
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Trajan recommends using an SGE inlet liner with wool to avoid unnecessary loss of high boiling point compounds.Many inlet liner designs include deactivated quartz wool packing, some of the reasons for this are:
- Provides additional surface area for complete volatilization of the sample to minimize sample discrimination.
- Traps non-volatile components and septum particles from reaching the column.
- Wipes any sample from the syringe needle, thereby increasing reproducibility and preventing sample residue build-up at the septum.
- ◄My results are showing low sensitivity/low response. Can a different inlet liner increase sensitivity?
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There are several factors which can affect sensitivity, such as inlet temperature being too high or too low. In the case that the inlet temperature is too low, raising the inlet temperature and using an SGE ConnecTite™ inlet liner will help increase sensitivity by minimizing sample loss.
- ◄Can the inlet liner help reduce baseline noise?
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Contamination in the inlet liner can cause an increase in baseline noise. Change your inlet liner regularly to minimize noise issues.
- ◄Can the inlet liner extend the lifetime of my GC column?
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A wool-packed or fritted inlet liner can help increase GC column lifetime:
- Quartz wool or glass frits can assist in homogenization of evaporated analytes and solvent in the inlet. They also help transfer the analytes to the GC column entrance.
- Wool or glass frits act as a filter by blocking non-volatile impurities from entering the GC column.
- ◄How often should I change my inlet liner?
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The lifetime of inlet liners is difficult to predict, as it will vary greatly depending on the nature of the samples being introduced.
- If headspace injection is being used, only vapors will enter the GC inlet and the inlet liner can remain clean for months.
- If ‘dirty’ samples are injected, it may be necessary to inspect the inlet liner daily.
- In all cases, as soon as the inlet liner has residue visibly building up inside, it should be swapped for a new inlet liner.
- ◄Can the inlet liner reduce peak tailing?
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Peak tailing can have several different causes, one of which is a dirty inlet liner, which increases active sites interacting with the injected sample as it is introduced to the GC column. If peak tailing persists, you may want to consider replacing ferrules, septa and o-rings, installing a guard column and/or using a different solvent for your analysis. Please contact techsupport@trajanscimed.com for further information or advice.
- ◄What are the benefits of using an SGE OptChem bottom taper inlet liner with glass frit?
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The SGE OptChem taper inlet liner with glass frit and pre-fitted CRS ONE o-ring provides the same benefits as a bottom taper inlet liner with packed quartz wool, plus some additional advantages:
- The glass frit exhibits improved density distribution compared with woolpacked liners. Since the glass frit has a consistent porosity, the gas flow rate through the liner is more uniform compared to packed wool, which increases reproducibility.
- Using a frit removes any risk of wool breakage, which can expose active sites within the inlet liner and reduce the sensitivity of the analysis.
- ◄Can I download these inlet liner questions and answers?
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Yes, the PDF is available from this page: Frequently Asked Questions - SGE inlet liners.
GC ferrules
- ◄What materials are available for GC ferrules?
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GC ferrules are available in graphite, Vespel®, Vespel-graphite and PTFE. View the full range of CRS GC ferrules.
- ◄Can I use graphite ferrules on my mass spectrometer connection?
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Graphite ferrules are porous to oxygen, therefore they are unsuitable for connecting columns to mass spectrometers.
- ◄Is 400°C really the maximum temperature for 100% graphite ferules?
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The 400°C maximum is based on some oxygen being present. Above 400°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 pressure is suitable for ferrules 072621 and 072622 100% graphite ferrules?
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These graphite ferrules are suitable for low pressure GC applications.
SilTite
- ◄Can SilTite ferrules be used with aluminium clad columns?
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In-house testing has 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?
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SilTite nuts and ferrules are only available for the MS interface.
- ◄Which SilTite kit should be used with the Thermo ISQ?
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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?
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No. SilTite ferrules can only be used with specific SilTite nuts which are characterized 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?
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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?
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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.
GC septa
- ◄Do any of the current range of GC septa have a PTFE lining?
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Puresep T septa are not low-bleed septa, and their recommended maximum temperature is 225°C. Puresep T septa are stamped from sheets of material to the size specified. All general purpose septa are produced to tight tolerances in dedicated molds. View our full range of CRS GC septa.
- ◄What is the thickness of your GC septa ?
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GC septa are 3 mm thick.
- ◄Do GC septa contain phthalates that can contaminate my analysis?
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Phthalates are seldom present in silicone parts. There are no phthalates added to the septa during the manufacturing process.
- ◄What type of CRS GC septa are equivalent to Trajan GC septa?
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CRS GC septa Trajan GC septa BTO (Bleed temperature optimized) HT AG3 (Advanced Green 3) EC Marathon MN GP (General purpose) GP Puresep T - Endura-Seal -
SilFlow
- ◄Tube insertion depth
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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)?
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It is 0.65 mm ID.
- ◄Sticking ferrrules in SilFlow
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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?
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We recommend connecting to an HPLC pump and backflushing the SilFlow to remove any debris.
- ◄Can I put my SilFlow in an ultrasonic bath?
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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?
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There is no practical temperature limit. The limitation will be the maximum temperature of the GC column.
Gas purifiers and filters
- ◄What type of CRS gas filters are equivalent to Trajan Big Traps?
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CRS ZPure™ gas filter Trajan Big Trap HC 750 cc Hydrocarbon H20 750 cc Moisture O2/H2O 750 cc Oxygen PolyGas I 750 cc Universal Wide filter mounting kit (with hardware) Mounting clip - ◄What is the difference between a purifier, a filter, and a trap in the CRS product line?
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- Filters “remove” one or two specific contaminants from a gas source such as removing oxygen from helium.
- Traps are considered to be the same as a filter.
- Purifiers “purify” a gas source from several contaminants such as purifying helium of oxygen, moisture, hydrocarbons, and other trace contaminants.
- ◄Should I mount them horizontal or vertical?
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Filters should be installed in a vertical position, so the gas stream travels through the entire adsorbent bed. Horizonal installation could create a void where the gas would travel and bypass the media by using the path of least resistance.
- ◄Should I use brass or stainless steel fittings?
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Match your fittings with your tubing. Stainless steel fittings are used with stainless steel tubing, and brass fittings are ideally used with copper tubing.
- ◄How long will my filter or purifier last?
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Many parameters go into choosing the correct filter and determining its life expectancy including the general application, the impurity and their levels, flow rates, pressure ratings, usage time, fitting requirements, etc. To get an accurate estimate of life expectancy before purchasing a filter, contact technical support. The specifications listed in product brochures are assuming quantities that would give about a one year life expectancy for each filter in general GC applications.
GAV-200
- ◄I am finding it difficult to get the sample bag out of the sampling canister. What should I do?
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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?
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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?
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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?
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Maximum temperature: 70°C
Minimum temperature: 5°C - ◄What is the canister in the gas and vapor sampling kit made of?
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The canister is polycarbonate and the cap is polypropylene.
- ◄What is the maximum pressure of the canister?
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The maximum pressure of the canister is 50 psi.
- ◄How can I sample from a low pressure source?
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When sampling from a low pressure source a vacuum can be applied to the canister.
- ◄What are the minimum and maximum operating temperatures for the gas and vapor sampling kit?
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Maximum operating temperature: 70°C
Minimum operating temperature: 5°C
Micro Control Valves
- ◄What is the Internal volume of MOVP part number 1236091?
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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?
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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?
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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?
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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?
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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?
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5 meters.
- ◄Do you manufacture packed columns?
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No.
- ◄How do I condition my capillary column before using it?
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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?
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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 supply FAME standards?
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We do not supply FAME standards, but there are a number of companies that do.
- ◄Why do my chromatogram peaks appear very broad?
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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?
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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.