Archive for the ‘Troubleshooting’ Category

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 […]

GC compounds – poor peak shapes and missing peaks

One of the most common questions I am asked by customers is “Why is my peak shape so poor?” Another is “I do not see a peak for my compound, what should I do?” Sometimes they are developing a new method and have no experience with the compound(s) of interest; other times things worked well […]

How (Not) To Cut Your Capillary Column

There are numerous ways to cut a capillary column. Restek has several tools to accomplish this job. There are sapphire scribes, ceramic scoring wafers, wafers with a handle, and diamond blade column cutters. There are also some tools manufactured by other companies that will cut a capillary column. The choice is typically personal preference. No […]

Don’t forget about your lab’s moisture traps/filters, especially when it’s summer

One of the common issues which arise in laboratories during the summer is moisture in the gas lines. Although I never quite understood how this would happen when using gas cylinders, it does, especially when a manifold system is used, or if the length of tubing from the gas source to the instrument is longer […]

Troubleshooting Injection Volume Variation in the Concurrent Solvent Recondensation – Large Volume Sample Injection Technique

I’ve started receiving a number of questions about the large volume injection technique called Concurrent Solvent Recondensation – Large Volume Sample Injection. Most recently, a question came through the Tech Service group about injection volume variation. I had encountered a similar problem when working on the 50 µL injection for the combined 1,4-Dioxane and Nitrosamines (EPA […]

Need parts for your Agilent 1100? HP 1050? Restek has you covered.

As of May 31, 2015, 1100 Series HPLC systems were categorized “End of Guaranteed Support” (EGS) by Agilent. Agilent would prefer it if you purchased a new system from them, but 1100 HPLCs are dependable workhorses. Why not keep them running with instrument replacement parts from Restek? Check out our selection, easily sorted by instrument and module: […]

Leak Detector Lithium Ion Battery

Lithium ion batteries have been in the news quite a lot recently, and not all of it has been positive.  There have been numerous incidents of different products from airplanes to hoverboards to mobile phones catching fire during charging or operation.  These problems occur when there has been damage to the cells’ structure or to the […]

Quadrupole Scan Speed and the 8270 Instrument Checkout Mix – Part II – The DFTPP Evaluation

Yesterday’s blog gave an overview of how choosing the wrong scan speed could be detrimental to the tailing factor evaluation. Before someone asks, I thought we’d spend today looking at the impact of scan speed on the decafluorotriphenylphosphine (DFTPP) tune evaluation. I know I’ve covered this before, but here are the tuning criteria from EPA […]

Quadrupole Scan Speed and the 8270 Instrument Checkout Mix

In my last blog (here), I promised an update on the impact of the detector scan speed on the tailing factor. I had speculated that a pentachlorophenol tailing factor value of 0.94 was more likely < 1.0 because of the scan rate, rather than column overload. The examples I put forward here were collected on […]

It May be Hot Outside, but Your Headspace Analysis Can Still Suffer from the Cold

Summer days are my favorite – hot, sunny, and full of fun. But one thing that’s really not fun is trying to track down contamination and/or carryover in your headspace-GC (HS-GC) system. I get questions about this topic pretty regularly, so I thought I would post a blog on the most common culprit for contamination […]