Posts Tagged ‘troubleshooting’

Is my LC instrument generating high pressure by itself?

We have had several blog posts and articles that discuss high backpressure observed in LC systems. Much of this discussion involves how to determine if the problem is in the column and what to do about it. Here are links to several of these: The Clog Blog Building up pressure on HPLC? Technical Service Red […]

Chemical Reference Standards: Don’t Just Snap and Pour (Part 2)

Several years ago, my colleague, Alan Sensue wrote Chemical Reference Standards; don’t just snap and pour. In it, he described a personal experience where he mixed several expensive reference standards together assuming the vials contained exactly 1 mL. It was a mistake he has remembered for some time. Here are a few other examples as […]

Troubleshooting 101

Like most folks who work in the lab, you likely have had some downtime in the lab due to various reasons, like a column, instrument, sample prep, standards, and even application or method conditions. Troubleshooting then commences. Details are often needed, in order to get the bigger picture. One of the most important troubleshooting tools […]

Solid Phase Extraction: Separation is the Foundation of this Preparation!

In a previous post, we made the case that the foundation for analytical separations is sample preparation.  In this post, we would like to talk about how it works the other way around, too!  Separation can actually be the foundation for sample preparation.   In particular, we would like to talk about how solid phase extraction […]

Potency: Useful Techniques

The most labor-intensive part of determining the potency of samples containing cannabinoids is extraction. Due to a plethora of matrices, from candy, baked goods, lotions, and so on, selecting the most suitable extraction method can also be a challenge.  The following video and technical article will guide you through that initial process: How Potent 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 […]

Need Help with QuEChERS: #AskRestek Twitter Q&A session

Just wanted to let everyone know we will be hosting a #AskRestek Twitter Q&A session about QuEChERS next week at 3:00 p.m. EST (12:00 noon PST) on Tuesday, May 3. QuEChERS is a great approach for sample preparation with lots of benefits. It is also very flexible which is nice but that can also make […]

More Technical Service “Red Flags” – LC

This post is the second of its kind pertaining to LC analysis, all of which are an extension of a series pertaining to “Red Flags” for GC analysis. These are situations and symptoms that tell us in the Tech Service group that something is just not right. As we discussed in the first post, Technical […]

The Most Useful Pesticide Standard Ever…monitoring GC inlet “dirtiness”

I have spent most of my time over the past several years testing pesticides and there is one standard that I simply can’t live without…QuEChERS Performance Standards Kit. It is based on a really interesting article* on analyte protectants with a few compounds added. The standard has 40 compounds housed in three vials for long […]