Archive for the ‘Troubleshooting’ Category

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 […]

Are My Shut-off Valves Contaminated?

Shut-off valves provide a convenient means to control gas flows and are often used in conjunction with gas chromatography systems.  There are several types of shut-off valves including ball valves, plug valves, and diaphragm-sealed valves.  Some of these valves, ball and plug valves included, use a silicone-based lubricant to make opening and closing the valve […]

Annual Replacement of Cartridge Gas Filters

A significant number of instrument and column complaints are carrier gas related, which could be caused by breakthrough from filters that are not replaced in time. The possible consequences of a filter breakthrough are: Gas distribution system behind the filter will be contaminated (fast cleaning nearly impossible, bleeds for months) Instrument gets contaminated, expensive maintenance […]

A better way to configure your EZ No-Vent GC-MS Connector

If you are using the EZ No-Vent for Agilent mass spectrometers (cat.# 21323), you are probably tricking your instrument into working properly by inflating the length of your column in your acquisition software. If you have MassHunter, or a recent version of MSD ChemStation  (G1701EA), you don’t have to do this. Instead of configuring your […]

Can I use a 100% aqueous mobile phase with my LC column?

You might be asking this because you have read that not all columns are OK to use with highly aqueous content (>95%) in the mobile phase.  Or maybe the caption caught your eye because you have recently encountered some difficulty with using highly aqueous mobile phase. There is a phenomenon called “phase dewetting” that can […]