HPLC

In recent articles, we reviewed the basic concepts of extracolumn dispersion and how this phenomenon can impact the quality of an LC separation. We now specifically discuss the effects of dispersion that can occur due to tubing and detectors.

Using ion mobility, analytes that have the same molecular mass can be separated by their shape, centers of mass, and collision cross section, but challenges such as ion loss can still occur. A new development in ion mobility separation, high-resolution ion mobility (HRIM), addresses such problems, and is particularly well suited to challenging applications, such as glycosylation monitoring of biological drugs and vitamin D analysis.

Two-dimensional liquid chromatography (2D-LC) allows much greater resolution of peaks than is possible in a classical single dimensional separation. For the next development in separations, we employed 2D-LC in two highly orthogonal dimensions of separation with four mass spectrometers for detection, with parallel detection in each dimension. We have further broken ground by using three dimensions of separation with four mass spectrometers, using two parallel second dimensions.

We present our annual review of new liquid chromatography columns and accessories, introduced between spring 2020 and spring 2021.

Dispersion of analyte peaks outside of chromatography columns can seriously erode the resolution provided by good columns. Here, we focus on the contribution of the sample injection step to the total level of extracolumn dispersion in an LC system.

Highlights of the new high-performance liquid chromatography, mass spectrometry, and chromatography data systems introduced over the past year.

We present our annual review of new products in gas chromatography, introduced between spring 2020 and spring 2021.

Dispersion of analyte zones outside of the column often compromises the quality of an LC separation—particularly in smaller columns with smaller particles. We explain basic concepts in extra-column dispersion from the point of view of an entire instrument.

Elmar Piel’s pioneering work was pivotal to the development of modern-day high performance liquid chromatography (HPLC).

Over the 17 years since the original Hydrophobic Subtraction Model for HPLC selectivity was published, those who curate the model have collected a huge amount of data as new HPLC stationary phases have been added. Analysis of this new data on almost 600 stationary phases has allowed us to update or adjust several of the stationary phase–analyte interaction terms within the model as well as adding one entirely new term to better describe the dipolar interactions with more modern stationary phases such as the pentafluoro phenyl-type phases.

Mycotoxins are toxic metabolites produced by fungal species often found in agricultural products. An accurate method for analyzing 12 regulated mycotoxins is described using UHPLC–MS/MS. The method demonstrated limits of quantitation (LOQs) for all analytes below stringent regulatory limits, making the method suitable for routine mycotoxin analysis.

LCGC Europe spoke to Stefan Van Leeuwen and Bjorn Berendsen from Wageningen Food Safety Research, The Netherlands, about a novel non-targeted approach to analyze PFASs using LC–HRMS with fragment ion flagging (FIF).

How do the characteristics of the mobile phase waves and retention properties of an analyte of interest impact retention precision?

Many of us have faced the situation where we have analytes that vary widely in their polarity or LogP(D) values and encounter issues with analyte solubility when choosing a suitable sample diluent for our high-pressure liquid chromatography (HPLC) analysis. The more polar analyte will favor aqueous solvents, and the less polar will be more highly soluble in organic solvent—so which do we choose?

This article reviews historical bonding techniques still in use for manufacturing high performance liquid chromatography (HPLC) stationary phases today, and also examines some emerging technologies that may be able to tackle unmet needs in novel platforms and phase construction.

Charged aerosol detection (CAD) is a powerful complement to ultraviolet (UV) absorbance and mass spectrometric (MS) detection for liquid chromatography (LC), particularly for analytes that have no UV chromophore, or do not ionize well by electrospray ionization. This article explores how to successfully use this technique.

The Dal Nogare award honors an awardee who is selected for contributions to the fundamental understanding of the chromatographic process. This year’s award winner is Professor Apryll Stalcup from Dublin City University.

This Friday morning session honors the 2021 LCGC award winners: Paul Haddad of the University of Tasmania, and the foundation director of the Australian Centre for Research on Separation Science (ACROSS); and Erik L. Regalado, of the pharmaceutical company Merck & Co.

Liquid chromatography (LC) pumps produce mobile-phase streams with short-term variations in mobile-phase composition. We explain the impact of these waves on retention time in reversed-phase LC and what to do about it.

A new free simulator is available for students, educators, and trainers to teach and perform virtual HPLC experiments that are applicable to real HPLC instrumentation and method development.

Even after 40 years, we have yet to find a perfect solution to the problem of demonstrating and achieving acceptable column precision for high-performance liquid chromatography (HPLC) packing material.

A UHPLC–MS/MS method is described for rapid quantification of five major bioactive alkaloids in rat urine. The results obtained help lay the foundation for the clinical application and safety evaluation of the bioactive ingredients of menispermi rhizoma, used in herbal medicines.

A review of the operating principles of modern liquid chromatography (LC) pumps based on low- and high-pressure mixing designs, and a look at how these pumps produce mobile phase streams with small short-term variations in mobile phase composition, with a focus on the effect of these mobile-phase composition “waves” on detector baselines.

Mixed-mode chromatography columns are on the rise. This article reviews recent fundamental research, stationary phase development and design, and areas of application.

Ron Majors was the 2020 recipient of the Chromatography Forum of the Delaware Valley (CFDV) Award, which is given to those who have provided exceptional service for the Forum in addition to outstanding contributions within the field of chromatography. Readers of LCGC are well aware of his nearly 60 years of research and leadership in this area (1), but few outside the Delaware Valley region know of his decades of membership on the CFDV Executive Committee, including two terms as president. As part of this well-deserved honor, Ron gave a (remote) address to the organization in October 2020, detailing his many accomplishments in the field and summarizing the current state-of-the-art in high performance liquid chromatography (HPLC) column technology (2). However, it was his introduction describing the early days of HPLC that stood out to me, specifically a name I had not heard before: Elmar Piel. For this month’s blog post, I invited Ron to join me in writing a bit more about this scientist who may be unfamiliar to many chromatographers.

Mixed-mode chromatography columns are on the rise. We review recent fundamental research, stationary phase development and design, and areas of application.

Liquid chromatography (LC) pumps produce mobile-phase streams with small short-term variations in mobile phase composition. We explain the origin of these variations and their effects on chromatographic performance.

Paul Haddad and Erik L. Regalado are the winners of the 14th annual LCGC Lifetime Achievement and Emerging Leader in Chromatography Awards, respectively. We review their achievements.

A method is described using a triple quadrupole LC–MS instrument with isotopic dilution to obtain the highest accuracy and confidence for analysis of per- and polyfluoroalkyl substances (PFAS) in water. Excellent method spike recoveries and robustness were found in wastewater.

Sometimes our approach to troubleshooting specific problems has to change in response to changes in high performance liquid chromatography (HPLC) technology over time. In this installment, we discuss changes in technologies for mobile-phase degassing, silica-based stationary phases, and models for reversed-phase selectivity.