Author Archive

GC columns – when one is not enough

Often we get asked for a column recommendation for a complex GC analysis.   This is especially true for gas analysis.  Probably the most common request is for separation of fixed (permanent) gases (like O2, N2, CO, CO2, N2O, etc…) plus separation of larger (higher-boiling point) compounds (light hydrocarbons, moisture, sulfur compounds, etc.).  Unfortunately, there is […]

Swagelok® and Parker® Tube Fitting Manuals

When asked by customers for what I consider the best reference guides on Swagelok® and Parker® fittings, I send them the following links.  I thought our blog readers may also benefit from these links, so here they are (below).  I hope you find them useful. Swagelok® Tube Fitter’s Manual Parker® Instrument Tube Fitting Installation Manual […]

Are your ghost peaks coming from the GC column, or something else?

  This is a common GC troubleshooting question.  Since determining the source of the ghost (contamination) peaks can be difficult, I decided to write this post to (hopefully) help our customers. . GC column carryover When I operated an instrument on a daily basis, it was only a matter of time before something caused ghost peaks […]

Broken fused-silica columns – it’s rare, but it does happen.

Once in a while we get a call that one of our GC fused-silica columns has broken, and customers ask if it can be repaired and used.  The answer is “maybe”. If your column broke while at a high temperature, and the column’s phase has been exposed to oxygen (air), then probably not.  A sure […]

GC capillary columns for the European Pharmacopoeia methods

Have you ever viewed a European Pharmacopoeia method and tried to figure out which Restek GC capillary column you should use? To make the selection a little easier for our customers, I decided to match the nomenclature listed in the European Pharmacopoeia “Reagents” chapter to the appropriate Restek columns.  I hope you find the table […]

Think twice before purchasing a 3/16” OD packed column

So you may be asking yourself, why the cautionary statement? Well, it’s very simple, many of our customers who purchase 3/16” OD (outside diameter) packed columns have a difficult time installing them into their GC oven.  Why?  Sometimes finding the appropriate fitting/ferrule is difficult. Let’s say you have a packed column instrument. If your injection port […]

What are these O-rings for that I received with my baseplate trap?

Some of you have noticed that included with several of our baseplate traps are a package of two small O-rings. Technical Service has been informed that these are the O-rings which fit onto the check valves on your baseplate (see red arrows below).  Does this mean that you need to replace these O-rings?  Not necessarily.  […]

Which GC injection port liner to use for gas samples

The answer seems fairly straightforward: Use a narrow internal diameter (ID) liner to keep peak shapes sharp by preventing band broadening; but this isn’t always the correct answer. There has to be enough internal volume in the liner to contain all of the sample.  Let me explain. Let’s first look at liners when using purge […]

Verify your GC packed/micropacked column carrier gas flow to obtain reproducible results

Working in technical service has taught me many things, but one of the most important has been “don’t assume anything”. This is especially relevant when it comes to verifying the carrier gas flow through GC columns.  To obtain reproducible results from column to column, this verification should always be done after installing a different packed/micropacked […]

Need help in selecting replacement weldments and shell weldments for your Agilent 5890/6850/6890 GC?

When you need a replacement weldment and/or shell weldment for your Agilent 5890/6850/6890 GC, we have the parts. However, selecting the correct catalog numbers can be a little confusing for many of us.  As a result, I decided to try and simplify the selection process below.  I hope you find it helpful.   5890 Weldment […]