Columns | The LCGC Blog

The technology and resources available in this digital world have really pushed the way that we can (and now may have to) teach.

As described in last month’s blog post, the ongoing global pandemic has transformed the way that educators approach teaching analytical chemistry. As I reflect back on my own experience from the Spring 2020 semester, one positive aspect that has come from the seemingly infinite number of video meetings has been the opportunity to connect with colleagues that we might not consider if it weren’t for the “new normal” of working remotely.

Optimizing gas chromatography (GC) separations typically involves making some informed choices around stationary-phase chemistry and column temperature programs

As our academic year comes to end, I always take time to reflect on what I have learned in the past year. As an assistant professor in Forensic Sciences and Chemistry at Chaminade University of Honolulu, I take the opportunity to review my courses regularly and implement new tools. Some of them will be successful and others will not.

We are frequently asked about issues with reduced peak size in gas chromatography (GC), and I’m guessing this is related to just how difficult this problem is to troubleshoot. There are so many potential causes that an inexperienced GC user may not know where to begin the troubleshooting process. Fear not. What follows is our logical guide to locating and fixing the issues with loss of sensitivity, and we’ve tried to cover as many of the instrument and application issues that we can think of.

My initial inclination was to write about something other than the current status of life, given the threats of coronavirus. However, after a month extension to the shelter-in-place was ordered by the U.S. government this past weekend, and after various e-discussions with friends and colleagues throughout the world who are experiencing similar challenges, I felt I might have something to offer to make life easier.

Most HPLC columns are packed with silica onto which some form of hydrophobic ligand is bonded – these columns form the vast majority of those used for modern reversed phase HPLC.

My initial inclination was to write about something other than the current status of life, given the threats of coronavirus. However, after a month extension to the shelter-in-place was ordered by the U.S. government this past weekend, and after various e-discussions with friends and colleagues throughout the world who are experiencing similar challenges, I felt I might have something to offer to make life easier.

Peak tailing is a problem that is regularly encountered in capillary gas chromatography (GC). It can cause issues with resolution and peak integration, affecting both qualitative and quantitative analysis. In this first of a series on GC diagnostic and troubleshooting, discover how best to identify the source of the issue, and find suggestions on how to prevent or fix the problems that underly the issue.

The 44th International Symposium On Capillary Chromatography (ISCC) and 17th GC×GC Symposium will be held at the Palazzo dei Congressi, in Riva del Garda, Italy, from 24–29 May 2020.

The selectivity (α) of an analytical system describes the ability to discriminate between sample components based on differences in chemical and physical-chemical properties.

It was a pretty significant fight to get our most recent paper into the scientific literature. But, after five reviewers opining and four submitted revisions later, we were able to publish a very unique piece of work characterizing anecdotal claims of groundwater contamination in shale energy basins across the United States.

I’m frustrated with static headspace sampling!

Looking back, the start of my penning of blog articles matches quite well with the start of efforts to investigate the potential environmental impacts of unconventional oil and gas extraction, and the formation of the Collaborative Laboratories for Environmental Analysis and Remediation (CLEAR; http://clear.uta.edu) at the University of Texas Arlington. It also well coincided with my effort to begin some outside consulting activities, predominantly the review of forensics evidence for blood alcohol determination. Both of these activities have blossomed considerably in the past seven years, and it has become interesting to contemplate the most rewarding way to spend my time going forward.

I’ve been dealing recently with issues in the laboratory when using ammonium acetate buffers, including surprising rises in HPLC–MS back pressures when starting the instrument after overnight storage, as well as difficulties with MS sensitivity.

I run into scientists all the time who have never heard the term exposome. Most are not intimately connected in the analytical world; these days, analytical scientists seemingly expect “ome” and “omics” to be tacked onto pretty much anything.

In HPLC Diagnostics Skills Part I we looked at baseline issues, and we continue here with HPLC peaks and in particular the skills required to identify tailing peaks, the causes of peak tailing, and most importantly, how to fix the issues that give rise to this peak deformation.

Theoretical computations can contribute input into experimental determinations.

I wanted to produce a checklist for preparation of a GC or GC–MS system prior to analysis, referencing the actions, checks, tools, and consumable items that might be required.

Traveling to interesting places for conferences and hearing new ideas is certainly one of the most enjoyable aspects of a faculty position. Recently, I attended the 16th International Interdisciplinary Meeting on Bioanalysis (CECE 2019) in Gdansk, Poland. I was absolutely delighted both by the city and the scientific quality of the meeting.

The improved performance of chromatographic detectors, most notably mass spectrometers, has enabled many advances in analytical science, however, one such advance may be given less prominence than perhaps it should.

In an effort to better understand the current application potential of microscale liquid chromatography (micro-LC), I picked up a few recent review articles from the literature. What one immediately appreciates from glancing through the literature for such information, is that there are a lot of different configurations and alternative formats, which can be placed under the micro-LC umbrella.

Our recent discussion on the use of hydrogen as a carrier for gas chromatography applications elicited many questions and comments, however one common question was “what are the considerations for using hydrogen carrier with MS detectors?”

Recently, I was honored to attend the 2019 Shimadzu Global Innovation Summit, hosted by Shimadzu Corporation in Kyoto, Japan. The focus of this meeting was to highlight innovation at the interface between analytical chemistry and medicine.

As I receive reports from clients in Europe and the United States that helium prices are once again increasing, and warnings are being given regarding yet another laboratory-grade helium shortage, my thoughts turn once again to the use of hydrogen as an alternative carrier-gas for gas chromatography.

As someone who has been associated very closely with poster presentations, I have to say, it is time for a change.

Exosomes are small lipid membrane-bound extracellular vesicles, on the order 30 – 150 nm in diameter, which are shed by normal and tumor cells in the body. They are circulating within your body and can be isolated from virtually any biological fluid. Exosomes released from tumor cells have been shown to be enriched in certain proteins. These nanobodies hold significant promise for the discovery of cancer biomarkers, for cancer diagnosis and prognosis, and for biomarker quantitation.

Modern HPLC method development is dominated by a small number of pH adjusting reagents and buffers that are prevalent even when the method uses UV detection. This is driven primarily by the requirements of mass spectrometry.

We have been working to develop the use of liquid chromatography–triple quadrupole–mass spectrometry (LC–MS/MS) for quantification of intact proteins from biological fluids.

To answer the question "Is there a good flow diagram I can use for GC method development?" please see below for our first attempt at something suitable, in the form of stepwise decision trees and flow diagrams.