Columns | The LCGC Blog

Researchers coupling high performance liquid chromatography to mass spectrometry face the challenge of segregating the ionized, typically nonvolatile analytes from a large amount of solvent, and the mobile phase is an important component in the process. LCGC Blog editor Kevin Schug discusses factors to consider when choosing a mobile phase for LC-MS.

Chromatography can be approximated by a series of equilibrium events between the mobile phase and stationary phase. Here, LCGC Blog editor Kevin Schug discusses an exceptional spreadsheet macro written by an undergraduate researcher that helps users visualize the development of chromatographic separations.

Chromatography can be approximated by a series of equilibrium events between the mobile phase and stationary phase. Here, LCGC Blog editor Kevin Schug discusses an exceptional spreadsheet macro written by an undergraduate researcher that helps users visualize the development of chromatographic separations.

Split/splitless injectors typically vaporise a sample dissolved in a suitable organic solvent under increased temperature. The sample vapours are entrained into the carrier gas flow inside a "liner" or "sleeve" within the inlet and from there pass into the column or out of the inlet via "split" line / valve. Splitless injection is used to perform an "on-instrument" dilution and the relative amounts of sample which enter the column or discarded to waste via the split line are adjusted using the relative carrier and split flow rate ratio.

J. Calvin Giddings provided one of the most practical discussions of the advantages of temperature programming in GC over isothermal analysis back in 1962. Here, Kevin Schug describes some of the salient points of that discussion and how they still apply today.

This month we take a look at the important topic of buffer choice for HPLC separations, how to the choose the correct buffer type and concentration as well as how to avoid variability in retention and selectivity.

J. Calvin Giddings provided one of the most practical discussions of the advantages of temperature programming in GC over isothermal analysis back in 1962. Here, Kevin Schug describes some of the salient points of that discussion and how they still apply today.

This month we take a look at the important topic of buffer choice for HPLC separations, how to the choose the correct buffer type and concentration as well as how to avoid variability in retention and selectivity.

It's important for chromatographers (particularly those who are also graduate students) to understand the fundamental aspects of separation science. In this installment of the LCGC Blog, Kevin Schug discusses the connection between thermodynamics and chromatography.

The nature of retention time changes in HPLC tends to fall into categories. Firstly, the retention time may "drift" over several injections or several analytical campaigns and secondly, the retention time may suddenly "jump to a different value between injections or between analytical campaigns (i.e. analyte retention times are very different to when that method was run last).

The physical characteristics of silica-based HPLC columns can affect the performance of the separation almost as much as the bonded phase. This month's technical tip re-visits some of the lesser known or remembered facts relating to silica particles used for chromatography.

This month we'll have a look at some tips and tricks on how to tighten up the robustness of our gradient methods and offer some quick calculations to check we're getting it right!

Kevin Schug discusses the power of MS for resolving an enormous number of compounds in a sample.

The physical characteristics of silica-based HPLC columns can affect the performance of the separation almost as much as the bonded phase. This month's technical tip re-visits some of the lesser known or remembered facts relating to silica particles used for chromatography.

Oceanographers have extremely challenging analysis problems to overcome. Can analytical chemists help? The Collaborative on Oceanographic Chemical Analysis workshop, sponsored by the National Science Foundation, connects scientists in these two fields to exchange ideas. And that is good, because the needs are great. Kevin Schug takes a look at where that collaboration might lead.

A number of retention time issues can cause problems in HPLC. Here's advice on how to handle common ones, such as retention time drift, temperature variability, problems arising from column equilibration, and difficulties validating a method.

Method validation is a concept that has been ingrained (or should have been ingrained) in the minds of most analytical chemists. Any new method that is created has to be proven reliable and provide some level of performance under well-defined conditions.

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Should HPLC eluent additives be added to one or both of the constituent mobile phase reservoirs - both organic and aqueous, when mixing gradients online?

The Technical Department at Crawford Scientific are regularly asked for analytical conditions or applications in the hydrophilic interaction liquid chromatography (HILIC) mode. Here?s a short primer on what you need to understand about this separation mode from a practical perspective, using some of the questions that we regularly get asked.

Derivatization of the analytes targeted in an HPLC-ESI-MS separation can help improve detection limits.

In this months technical tip we answer some often asked questions and dispel some myths regarding HPLC column abuse and reconditioning

In this months technical tip we answer some often asked questions and dispel some myths regarding HPLC column abuse and reconditioning

Restricted-access media (RAM) offer many advantages and can make it easier to achieve efficient and reproducible on-line sample preparation. In spite of this, these media have been underutilized. It is time for more research into RAM.

A review highlighting the recent development on flow-injection analysis (FIA)–mass spectrometry (MS) to bring more attention to this effort.