Archive for the ‘Troubleshooting’ Category

Why is my LC Retention Time Shifting?

If you have experienced retention time shifts with LC, you know it can be complicated and can cause problems with quantitation if not resolved. Hopefully this post will help you navigate through troubleshooting this situation. For the purposes of this discussion, we will be discussing changes in retention on one individual column, not differences from […]

Over tightening your fittings has consequences.

If you use the correct fittings and seals in the gas chromatography system, and follow some simple steps, there is absolutely no need to over tighten any fitting to achieve a leak free seal. For almost all fittings that use seals in a GC system, whether they are ferrules, septa or o-rings, the tightening process […]

Using a liquid leak detection solution has consequences

We have been warning about the consequences of using liquid leak detection products for years (see Blog).  These products, like Snoop, contain a whole host of compounds that can easily contaminate your GC system if you have a leak.  The solution can enter the leak site by capillary action, and is very hard to remove, […]

Discovering Analyte Breakdown On-Column

I completed my winter internship at Restek and my main task was to expand the Pro-EZGC libraries. So I created a library for Nitrosamines on the Rxi-1301Sil MS and while acquiring data we noticed a foot on a couple of my peaks. I attempted to translate the simulation to a column with the same phase, […]

Poor press-tight connections have consequences

My colleagues have written plenty of articles over the years with how to cut columns and get the perfect press-tight connection: Jaap – How to make a good fused silica seal using a Press Tight type connections Jaap – Column cutting, for making the optimal coupling Chas – How (not) to cut your capillary column […]

Want to learn about “Injection Techniques in GC” or “Practical Maintenance and Troubleshooting in GC”? Sign up to join our half day course during Pittcon, Chicago.

Please join one of our courses presented next Pittcon in Chicago: “Injection Techniques in GC”:  Monday,  March 2,  08:30-12:00, Session: SC1230. “Practical maintenance and troubleshooting in Gas Chromatography”: Tuesday, March 3, 08:30-12:00, Session: SC1231 For location, visit short course office at S100C.   Injection Techniques in Gas Chromatography In Gas chromatography the most important process […]

Falling Victim to One of LC’s Classic Blunders: Mismatching Your Diluent and Mobile Phase

An early lesson most of us learn in liquid chromatography is this: Always match your diluent to your mobile phase.  Once the exams are done, if you learned this in a college course, or your manager has walked away, you start flexing this “requirement” a little to see how matched they really need to be.  […]

My fitting nut has broken off in the end of my LC column. What to do?

If excessive force is applied at an angle to a fitting or column connector, the ferrule could become stuck in the column end fitting. Likewise, a PEEK connector, column nut or plug can also break and leave part of it in the end fitting. Stainless steel nuts are much harder to break, although a stainless […]

Limitations of Alumina: What you should NOT inject on alumina / Al2O3 columns

Alumina (Al2O3) capillary PLOT columns have been available for about 35 years. They are best suited for separation of C1-C10 hydrocarbons and especially the C1-C5 range. The alumina has unique selectivity making it possible to separate all the unsaturated hydrocarbons at temperatures above ambient, see figure 1. While its an excellent choice for unsaturated hydrocarbons, special attention is […]

Tailing solvent peak during split injection? Check your column installation distance!

When performing splitless injections, it is not uncommon to witness a tailing solvent peak, given the large amount of solvent introduced onto the column over a relatively long period of time.  For split injections, however, only a small portion of the solvent loads onto the column and it occurs very quickly. This results in a […]