HPLC

The functional principles of AF4 and HF5 are discussed.

A global lipid method has been developed using a charged aerosol detector that resolves and detects numerous classes of lipids in a single analysis. The method was used to characterize complex oil samples.

The use of UHPLC has triggered a remarkable increase in efficiency and throughput of LC and LC –MS methods. The fastest growing market segment in the pharmaceutical industry is biopharmaceuticals, with an increased interest in applying UHPLC to biopharmaceutical analysis.

Achieving a high quality sample separation is critical to the success of UHPLC analyses. Numerous practical factors must be considered to achieve this.

A new method to optimize liquid chromatography (LC) methods using a Quality by Design (QbD) approach is presented. This method is based on the use of design of experiments (DOE) and independent component analysis (ICA) to accurately estimate the modeled responses (that is, the retention times at the beginning, the apex, and the end) of each peak, even for coeluted peaks. This method was applied to the optimization of the separation of nine compounds in a mixture, yielding the design space and the demonstration of robustness of the method.

The underlying principles of gradient elution HPLC are very different from those of the isocratic mode. Appreciating the differences can lead to better methods.

The underlying principles of gradient elution HPLC are very different from those of the isocratic mode. Appreciating the differences can lead to better methods.

Evidence to demystify HPLC and UHPLC column myths

A method is described that incorporates a mobile-phase gradient consistent with a HILIC separation mechanism and uses a mixed-mode column, which provides reversed-phase and cation-and anion-exchange properties, and charged aerosol detection.

Can anything be done to correct for baseline drift in gradient separations?

Can anything be done to correct for baseline drift in gradient separations?

The fundamental concepts of HPLC are re-examined.

Gradient methods can offer unique solutions to separations problems, but transferring a gradient method from the literature, between laboratories, or even within the same laboratory can be a challenging process.

This article will explore what is meant by "complete data" in the context of a chromatography data system and, with an analysis of FDA 483 citations, explore the problems when a laboratory fails to understand this phrase.

How can the gradient dwell volume impact results?

Recombinant monoclonal antibodies (MAbs) are a growing class of therapeutic molecules. Early in the development of MAbs, a large number of harvest cell culture (HCC) samples must be screened for immunoglobulin G (IgG) titer, aggregations, and charge variants. This study describes a two-dimensional (2D) high performance liquid chromatography (HPLC) workflow for afinity, size-exclusion, and ion-exchange analysis.

Click here to view the complete E-Separation Solutions newsletter from May 16, 2013.

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!

Click here to view the complete E-Separation Solutions newsletter from May 2, 2013.

Many different column characterization probes and databases exist. The art of using in-silico column selection lies in knowing what the probes tell us about the column characteristics.

Some "rules of thumb" can be applied to selecting stationary-phase type and column dimensions.

Part I of Ron Major's report on new products introduced at Pittson. This month, columns are highlighted, covering all modes of high performance liquid chromatography (HPLC), ultrahigh-pressure liquid chromatography (UHPLC), and liquid-phase separations.

A novel method for analysing mercury in sediment is described.

Sometimes when changes are made to gradient conditions, the result isn't what was expected.

Fabrice Gritti of the Department of Chemistry at the University of Tennessee (Knoxville, Tennessee, USA) discusses results from his and Georges Guiochon's research on the kinetic mechanisms of chromatography columns packed with core-shell particles.