Posts Tagged ‘troubleshooting’

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 […]

QuEChERS – Where to start?

Enjoy the tip!* I am often asked for QuEChERS product recommendations. Usually the request is something like, “I need to test pesticides in _____” and that blank can be just about anything…sometimes not even food. Unless it is something I have tested before, I usually take a quick look online to determine the approximate composition […]

How Dirty Are You? Part 2…Pipet Bulbs…The Answer

Check out the first How Dirty Are You? blog about Parafilm. The How Dirty Are You? pipet bulb blog showed some interesting data…mainly that I need to clean my pipet bulbs and periodically replace them. I am happy to report that I have changed my pipet bulb twice since and even do some solvent rinses. […]

How Dirty Are You? Part 2…Pipet Bulbs…The Question

Check out the first How Dirty Are You? blog about Parafilm®. This How Dirty Are You? blog is all about pipet bulbs. Our lab has 14 people and we have at least a few types of pipet bulbs for both borosilicate glass Pasteur pipets or volumetric pipets. I am sure this isn’t surprising to most […]

[4]Troubleshooting HPLC- Fronting Peaks

Patterns in your HPLC chromatography can exhibit telltale signs that point toward probable sources of error.  In this brief series of posts, we have looked at possible scenarios that you may encounter in the laboratory and how you might approach resolving those difficulties. Any time you have difficulty with poor peak shape, it is also […]

Now you see it, now you don’t – Troubleshooting method recovery problems

We sometimes get calls from analysts that just can’t seem to get acceptable recovery results for the method they’re performing.  Regardless of the analytical technique, a methodical approach to identifying the problem is always essential. The first step should be to define the problem. Answer the following questions: Does the chromatography for your quantitation standards […]