Chiral separation screening has become a widely accepted approach for the rapid identification of an appropriate chiral stationary phase for use in more focused enantioseparation optimization. A set of extended screens encompassing various chromatographic modes using HPLC and SFC is presented.
Agilent Technologies
Online SPE–LC–MS/MS combined with the method presented enabled automated cleanup of food extracts and determination of PFAS compounds in the ng/kg range.
This analysis offers insight for optimizing the structure of monoliths.
The ability of size-exclusion chromatography (SEC) to measure critical protein characteristics, such as molecular weight and size, makes the technique valuable from the early stages of novel protein research and development through to formulation and manufacturing support, especially in oligomeric purity and aggregation studies. However, informational output, ease of analysis, and sample requirements all vary considerably depending on whether a system has been truly optimized for protein characterization. This article examines how SEC works and considers how to maximize the productivity, sensitivity, and value of an SEC setup for biopharmaceutical development.
The authors present the most common and fundamental techniques that address common matrix issues and discuss the critical chemistry considerations.
This tutorial on reversed-phase LC explains the role of solvent, chain conformation, solute position, and retention dynamics.
Lactulose, a semi-synthetic disaccharide, is a useful indicator for heat induced modifications in milk. Lactulose can be derived from lactose by alkaline isomerization or enzymatic transgalactosylation of fructose.
The Column spoke to Steve Maynard, Lab Director at LGC's HFL Sport Science, about his work in the world of horse doping and his laboratory's involvement in this years Olympic and Paralympic Games.
Direct sample analysis coupled to high-resolution time-of-flight mass spectrometry (TOF-MS) may be effective at analyzing synthetic cathinones, especially for qualitative analysis, because it does not require potentially tedious sample preparation.
What are the characteristics and relevant considerations for the development and validation of a stability-indicating method?
Detailed examples of light-scattering techniques are presented as well as how their performance compares to MS and other methods.
The interface between the two separation dimensions is a key element of any comprehensive two‑dimensional liquid chromatography (LC×LC) system. LC×LC has typically been implemented by using one or more switching valves, equipped with either sampling loops or trap column(s). Temperature manipulation is a relatively unexplored yet promising route towards non-valve-based LC×LC. The fairly recent emergence of thermal modulation has provided a less conventional method for performing LC×LC separations. This article illustrates the variety of commonly used modulators, paying specific attention to focusing modulators.
This instalment provides an overview of the modern trends and best practices in mobile-phase selection for reversed-phase liquid chromatography (LC). In particular, we focus on selection criteria and rationales for enhancing analytical performance and ease of preparation.
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.
5-Fluorouracil (5-FU) is a low-molecular-weight anticancer drug in clinical use for several solid tumors in humans. Currently, the most widely used methodology for 5-FU quantitation is liquid chromatography–tandem mass spectrometry (LC–MS-MS) with either liquid–liquid extraction (LLE), protein precipitation, or a combination of both as sample cleanup procedures.
The aim of this work was to find the optimal conditions to achieve sufficient limits of detection (LOD) that would permit the detection of neurotransmitters by LC–MS–MS in biological samples. An optimized HILIC–ESI–MS–MS system for the analysis of the 12 selected compounds was proposed.
Analysis time can be reduced 10–30% by switching from constant-flow-rate mode to a constant-pressure gradient-elution mode.
This troubleshooting study of a problem of retention time variation provides a good example of how to track down the source of a problem and how to speculate on probable cause.
A method for the determination of pyrethroids in water at ultra-low-level concentrations of 0.02 and 0.10 ng/mL was developed using solid-phase extraction (SPE) for pre-concentration and subsequent analysis by GC with PTV injection.