Archive for the ‘GC Injection Techniques’ Category

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 […]

Optimizing Splitless Injections: Initial Oven Temperature and Solvent Polarity

Beyond optimizing the inlet parameters of temperature and splitless valve time, initial oven temperature also plays an important role for splitless injections. When a liquid sample is injected into a GC, the first goal is to vaporize the sample within the inlet and transfer it to the column. As you know, this sample volatilization and […]

Optimizing Splitless Injections: Splitless Purge Valve Time

In my previous blog, I discussed optimizing inlet temperature for splitless injections.  Today I would like to discuss another critical parameter for splitless injections: splitless purge valve time.  The key feature of a splitless injection is that all the carrier gas flow is directed to the column and the splitless valve is closed during injection.  […]

Optimizing Splitless Injections: Inlet Temperature

One of the key parameters that requires optimization for splitless injections is inlet temperature.  With liquid injections, the analyst is relying on the volatilization of the sample upon introduction into the inlet.  The analytes can then be efficiently transferred to the column in a vapor state, where they are refocused, prior to beginning the chromatographic […]

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 […]

Optimizing Splitless Injections: Introduction

Split and splitless are the two most common modes of injection for GC.  Each has its own set of pros and cons, with the required method sensitivity vs the sample concentration ultimately dictating which one to use.  For trace level analyses, a splitless injection is often the best choice, as the goal is to recover […]

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 […]

Purge and Trap weldment installation

Sometimes we get asked by customers for clarification when installing/connecting a new or replacement weldment from their purge & trap autosampler to their Agilent GC’s split/splitless injection port. As a result, I wrote this post to assist those that may be new to this type of installation or those that simply could use a quick […]

Does the Amount of Wool in Prepacked Liners Matter?-Part I: Experimental Setup

If you’ve followed my previous blogs on GC liner selection, you will know that the wool in inlet liners plays an important role for both split and splitless injections (GC Inlet Liner Selection, Part I: Splitless Liner Selection and GC Inlet Liner Selection, Part II: Split Liners).  Just to review, wool can enhance vaporization, promote […]

Terpene Analysis Approaches – Part III

It’s time to dive back into analyzing terpenes! Previously, we looked at two types of sample preparation for analyzing terpenes via HS-Syringe and HS-SPME. If you missed those blogs, be sure to check them out here and here before moving on! In my last blog, I showed that HS-SPME outperformed the HS-Syringe when analyzing terpenes. […]