Archive for the ‘Miscellaneous’ Category

Water, can’t live without it so how can we deal with it (and adsorbent columns)

Often the gas samples contain some water vapor. Although we are usually not interested in the amount of moisture present in the sample, if we don’t dry it, the water will be injected onto the column with our sample. Alan, in his blog, has previously discussed the effects of water on capillary columns with liquid […]

Thermo Trace 1310 Inlet Temperature Profile vs Agilent 7890 for Split/Splitless Injectors

Several years ago, my colleague Scott Grossman wrote an excellent article entitled “It’s a Matter of Degrees, but Do Degrees Really Matter?”  He measured the temperature profile across various Agilent inlets, demonstrating different gradients in temperature exist across inlets, depending on the type of inlet and even among the same inlet type.  One consistent finding […]

Spring Cleaning Your GC System

Spring has sprung and now is a good time to give your GC system a thorough going over.  There is routine maintenance that we should perform all the time to keep the GC in tip-top condition like changing the liner, o-ring, septum, using your electronic leak detector and column trimming; but there is also periodic […]

Analysis of noble and permanent gases on adsorbent columns

Predicting selectivity characteristics of adsorbent columns is often a wild guess. Yes, we know argon will have less retention than krypton, but how well do adsorbent columns separate noble gases from permanent gases? Can neon and hydrogen be resolved using a porous polymer column or do we have to use more retentive columns, like Molecular […]

Chiral Separation on a C18 Column? Separation of d- and l- Amphetamines Part III

To continue my blog parts 1 & 2 (Part 1:https://blog.restek.com/ p=67087,https://blog.restek.com/chiral-separation-on-a-c18-column-separation-of-d-and-l-amphetamines-part-ii/) , where I have discussed the importance of separating the chiral d- and -l isomers to accurately identify the illicit isomer using an achiral method on a Raptor C18 column employing a pre-column derivatization technique. Today I’d like to discuss more about the sample […]

Are PFAS sticking in your system?

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in our society and can be found in a wide range of consumer products; hence they are widely present in the environment, people and animals. They are persistent chemicals that have the potential to accumulate. Therefore, they are evaluated and monitored using a variety of methods and controlled […]

Does the Amount of Wool in Prepacked Liners Matter?-Part II: Results

In Part I of this series, I posed the question of the impact of the amount of wool on liner performance.  As a reminder, this study specifically examines Topaz liners that are prepacked with wool and then deactivated. With your own hand-packed liners these results will not apply. The first criteria I wanted to examine […]

A Few Ideas for Chromatographers During the Covid-19 Situation

The other day, I and some of my colleagues started a discussion about how chromatographers are handling the current Covid-19 situation. Some are working from home, and some are experiencing temporary closures. Those that are working are likely working under “new” conditions – social distancing, additional personal protective equipment, possibly working different shifts, etc. Since […]

The eVol – Investigating a Liquid Handling Tool to Improve Consistency and Reliability for Calibrations

We’re taking you to Austin, Texas to meet the amazing team at Santé Laboratories for this investigation! This project, led by the analytical team at Sante Laboratories, put the eVol in use and compared it to standard pipetting techniques in the generation of analytical calibration curves. Wait….what? You might be thinking to yourself….What’s an eVol? […]

GC Inlet Liner Selection, Part IV: Liner Volume and Diameter

In parts I and II of this blog series I discussed the various liner configurations available for both split and splitless analyses.  One thing I did not mention was liner volume and inner diameter.  Most of the liners I compared are available in multiple inner diameters.  For the comparisons I did, I used a 4 […]