October 29th 2024
Manitoba Centre for Proteomics and Systems Biology scientists produced a new means of predicting peptide retention times for hydrophilic interaction liquid chromatography (HILIC) at acidic pH in formic-acid based eluents.
Ultrahigh-efficiency separations based on the presence of one deuterium in benzene, toluene, and naphthalene were achieved by recycle chromatography using C18 silica columns. Larger isotopic separation factors, α(H/D), were observed in methanol–water than in acetonitrile–water, when the mobile phases provided similar retention factors (k), or similar methylene selectivity, α(CH2). Isotopic resolutions between nondeuterated and perdeuterated aromatic hydrocarbons at long separation times were estimated by using the plate counts obtainable by recycle operation as a function of a cycle time, along with the retention factors and the separation factors experimentally observed.
The Progress Made in Peak Processing
May 1st 2019This article gives a brief overview of the advantages and limitations of recently introduced mathematical procedures such as the Fourier deconvolution of extracolumn effects, iterative curve fitting, multivariate curve resolution, modified power law, and use of first and second derivatives in enhancing resolution. High-throughput analyses in gas chromatography (GC), LC, and supercritical fluid chromatography (SFC) could benefit from these simple and effective approaches in many challenging separations applications.
Reversed-Phase Liquid Chromatography and Water, Part I: How Much is Too Much?
February 1st 2019In reversed-phase separations, retention generally increases as the fraction of water in the eluent increases. When we encounter situations where retention is too low for an analyte of interest, we tend to use eluents with higher and higher levels of water. But how much water is too much?
High-Flow Weak Cation Exchange for Charge Variant Analysis
November 12th 2018Within the broad scope of analytical techniques required to characterize a protein, chromatographic methods have shifted towards high-flow analyses that can drop development time significantly. However, fast analytical methods for charge heterogeneity have lagged in development because current column technologies are ultrahigh-pressure liquid chromatography (UHPLC)-incompatible. This article will demonstrate the development of a high-flow method for charge variant analysis made possible through a bioinert titanium column flow path.
Scaling LC Methods Using Porous Particle Stationary Phases
October 1st 2018The use of ultrahigh-pressure liquid chromatography (UHPLC) is now commonplace among pharmaceutical laboratories. However, until depreciation cycles replace traditional high performance liquid chromatography (HPLC) systems that operate at a maximum pressure of 400 bar, the advantages of UHPLC cannot be realized worldwide. Thus, product methods developed using UHPLC capabilities cannot directly transfer these methods to receiving laboratories without qualified UHPLC availability.
Two-Dimensional Liquid Chromatography Does More Than Increase Peak Capacity
July 16th 2018Two-dimensional liquid chromatography (2D-LC) is drawn out of the chromatographic toolbox if resolution for compounds of interest is insufficient. Recently, several studies have started to highlight 2D-LC as a tool of choice to streamline analytical workflows to increase automation making them less time-consuming. This article highlights two proven cases where 2D-LC does more than simply increase peak capacity.
Robustness Modelling in Ultrahigh-Pressure Liquid Chromatography Methods
July 16th 2018Many workers in pharmaceutical laboratories are unable to change any aspect of their methods, although they often encounter severe problems and create many out-of-specification (OoS) results. They are particularly afraid to investigate these problems from a chromatographic perspective in case they generate new unforeseen problems. In the literature, however, there are numerous examples showing that it is worthwhile trying to understand the reasons for “unexplainable” behaviour in ultrahigh-pressure liquid chromatography (UHPLC) using modelling. By using modelling, problems can be recognized and often eliminated with legal operations according to the allowed tolerance limits mentioned in pharmacopoeia descriptions. The following article aims to show that “visual chromatographic modelling” can be a useful aid.
Chiral Chromatography in Antiepileptic Drug Development and Epilepsy Therapy
April 16th 2018The Column spoke to Arcadius V. Krivoshein, Assistant Professor of Chemistry at the University of Houston–Clear Lake, USA, about his work developing EPP, an experimental anticonvulsant that can help to stop convulsions during epileptic seizures, and the role of chiral HPLC in this research.
New HPLC Systems and Related Products Introduced in 2017–2018: A Brief Review
April 1st 2018This instalment describes high performance liquid chromatography (HPLC) and related products introduced at Pittcon 2018 in Orlando, Florida, USA, and in the year prior. It highlights new HPLC and mass spectrometry (MS) systems, modules, chromatography data systems, and other HPLC-related software and provides brief descriptions of their significant benefits and innovative features.
Biomimetic Chromatography to Accelerate Drug Discovery: Part 1
February 1st 2018The drug discovery process can be accelerated by chromatographic profiling of analogs by measuring their nonspecific binding to proteins and lipids and then by modelling in vivo distribution. A balanced potency and chromatographically determined membrane and protein binding ensure the selection of compounds with the highest probability to show the desired in vivo distribution behaviour for efficacy and reduced toxicity. The first part of the article will discuss the high performance liquid chromatography (HPLC)-based measurements of lipophilicity and biomimetic properties, while the second part will discuss the models derived from the measured data of known drug molecules and drug discovery compounds.