Archive for the ‘Packed Columns’ Category

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 […]

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 […]

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 […]

Understanding packed column mesh size ranges

If you have ever ordered a packed column, you are aware that mesh size of the solid support (packing) is one of the specifications you will need to know.  But have you ever wondered what mesh size actually means? To find the answer, let’s look at the products and process.  The necessary products are ASTM […]

Optimizing the performance of your D3606 column set

. My previous post “Simple tips to help your D3606 column set last longer” provided several recommendations for maximizing the lifetime of this column set.  In this post, I will provide suggestions to help you reproduce the results of the QA test chromatogram which was included with your column set. . 1.  Thoroughly review the […]

Simple tips to help your D3606 column set last longer

. Years ago, Restek developed a packed column set for ASTM D3606 “Standard Test Method for Determination of Benzene and Toluene in Finished Motor and Aviation Gasoline by Gas Chromatography”.  More specifically, this two column set (catalog number 83606-___) replaces the three column set listed in ASTM D3606-10, “Appendix X1. Resolving Benzene from Ethanol, Section […]

Molecular Sieve 5A & 13X packed columns – Installation / Conditioning / Helpful Hints

Molecular Sieve 5A & 13X Columns (packed) Molecular Sieve 5A & 13X (micropacked) Things to Consider Before Ordering a Packed Column . Following the steps below will ensure that your Molecular Sieve packed column is ready to use just several hours after installation.  You should only use dry high-purity Nitrogen as the carrier gas to […]

Molecular Sieve Packed Columns and Fixed (Permanent) Gas Analysis

For some reason, I find molecular sieve packed columns interesting.  Maybe it’s because they have a niche as the go-to columns for fixed (permanent) gas analysis.  Maybe it’s because they are old school technology that a new generation of analysts are always asking questions about.  Maybe it’s because using them successfully is a function of […]

Gas Flows in Packed and Micro Packed Columns

We received a question from a customer who did not obtain the correct flow through his micro packed column.  It is often not clear what flow is used in packed columns.  General the optimization  of flow setting using packed columns, does not have a priority as packed columns are –per definition-  low efficiency systems and […]

GC carrier gases, do you really have a choice?

With the ongoing helium shortage, there are still plenty of analysts looking for alternative GC carrier gases.  So what other options are out there, and are they really viable?  In this post, I will briefly discuss the two most common alternatives (hydrogen and nitrogen), and when they really can’t be used as an alternative to […]