I’m often asked “what reproducibility should I expect to get from my [insert instrument manufacturer and model]?” So, most folks are referring to the repeatability aspects of precision, as in: “what relative standard deviation (usually expressed at %RSD) for peak area or quantitative result should I be able to achieve from repeat injections from a single vial of sample?”
Click the title above to open the LCGC North America June 2017 Application Notebook, Vol 35 No s6, in an interactive PDF format.
Precise and accurate quantitative analysis based on chromatographic measurements has historically relied very heavily on careful peak integration. Seasoned analysts know that while automated algorithms exist in modern chromatography software, it is a best practice to manually check that the integration points-the points at the beginning and end of a peak, between which the peak will be integrated to obtain a peak area-are appropriately specified.
This information is supplementary to the article “Utility of the Summation Chromatographic Peak Integration Function to Avoid Manual Reintegrations in the Analysis of Targeted Analytes” that was published in the June 2017 LCGC North America issue (1).
An excerpt from LCGC’s e-learning tutorial on high performance liquid chromatography (HPLC) methods at CHROMacademy.com
When you want to adjust a United States Pharmacopeia (USP) method for a different size column or to meet system suitability criteria that fail, how much of a change can you make without revalidating the method?
This yearly report on new products introduced at Pittcon 2017 (or in the preceding year) covers sample preparation instrumentation, supplies, and accessories.
In reversed-phase liquid chromatography (LC), C18 alkyl-based stationary phases have been the favourite of method developers. Phenyl stationary phases are an alternative that are thought to benefit from additional π-π mechanisms. Recently, there has been a growing interest in the use of phases based on the biphenyl moiety. This instalment of “Column Watch” looks at the retention mechanisms of biphenyl phases and contrasts them with those of more-common alkyl phases.
The 24th International Symposium on Electro- and Liquid Phase- Separation Techniques (ITP 2017) will be held in Sopot, Poland, at the Sheraton Hotel, 10–13 September 2017.
In biphenyl phases, the surface chemistry often makes it possible to separate compounds not well resolved by C18 or phenyl phases.
How much of a change can you make to a USP method without revalidating the method?
Improve your analysis of ionizable analytes with these hints and tips.
An introduction from the guest editor of this special supplement from LCGC Europe and LCGC North America revealing recent developments in high performance liquid chromatography (HPLC) and ultrahigh-pressure liquid chromatography (UHPLC).
In the 21st century, numerous advances have been made in liquid chromatography (LC) column technology. The best known are columns packed with sub-2-µm porous particles or sub-3-µm superficially particles, and monolithic columns. Another very novel and original development is micro-pillar array columns (µPAC). µPACs are produced by a lithographic etching process to create a perfectly ordered separation bed on a silicon chip. Although the performance in terms of efficiency has been illustrated, the applicability for analysis of real complex samples has yet to be fully demonstrated. This article illustrates that state‑of‑the‑art µPAC columns coated with octadecyl are applicable for a challenging application such as lipidomics. The performance is illustrated with the analysis of human blood plasma lipids.
Mixed-mode high performance liquid chromatography (MM-HPLC) involves the combined use of two (or more) retention mechanisms in a single chromatographic system. Many original stationary phases have been proposed in recent years with promising possibilities, while applications have only started to appear in the literature. In this review, the authors discuss mixed-mode chromatography stationary phases. An overview of applications using mixed-mode chromatography is described, as well as the increased interest in mixed-mode systems for two-dimensional chromatography.
Enantioselective high performance liquid chromatography (HPLC) is slowly adopting the modern particle technologies (sub-2-µm fully porous particles [FPPs] and sub-3-µm superficially porous silica particles [SPPs]) that have been well known in reversed-phase LC for the past decade. The most significant benefit is that enantiomer separations can be performed much faster, which is of interest in high-throughput screening applications and multidimensional enantioselective HPLC analysis. The state of the art is briefly discussed with some examples documenting the potential of core–shell particle technology and comprehensive multidimensional separations.
The aim of this article is to illustrate the current status of computer-assisted method development and retention modelling. This study focuses on the successful method development of typical small pharmaceutical compounds (impurity profiling) and large therapeutic proteins. By choosing appropriate initial conditions, the method development can be performed in less than one day. However, for small molecules possessing different physicochemical properties, the conditions can be multifarious, while for biopharmaceuticals (for example, monoclonal antibodies [mAbs], antibody–drug conjugates [ADCs]), a generic method can easily be developed. In addition to retention modelling and optimization, the potential of simulated robustness testing is also demonstrated. Depending on the applied retention model, the impact of any change among six experimental parameters (tG, T, pH, ternary composition, flow rate, and initial- and final mobile phase compositions) on the separation can be assessed using a 26 or 36 type virtual
Quality and consistency in reagents is critical to successful drug discovery and development. When targeting a particular protein of interest, in vitro experiments should be performed with proteins of biological properties similar to those for in vivo tests. It is important that molecularity, purity, shape, and degree of heterogeneity remain the same when any alterations are made to the model protein or the formulation buffer. Multi-angle light scattering (MALS) combined with size-exclusion chromatography (SEC-MALS) is a very useful technique to monitor the solution properties of the protein as changes to reagents are made.
Click the title above to open the LCGC Asia Pacific June 2017 regular issue, Vol 20, No 2, in an interactive PDF format.
Click the title above to open the LCGC Europe June 2017 regular issue, Vol 30, No 6, in an interactive PDF format.
