The functional properties of polymers, such as poly(lactic-co-glycolic acid) (PLGA), relevant to drug delivery and biomedical devices, are governed by the molecular properties of molar mass, composition, conformation, and branching. This article demonstrates how such polymers are fully characterized, quickly and absolutely, using gel permeation chromatography (GPC) with multi-angle light scattering (MALS) and online viscometry.
Approximately 40% of recombinant proteins that are purified use a histidine tag for easy capture. This article covers how to automate the purification of histidine-tagged proteins and how purification conditions can be optimized to an automated four-step purification scheme that uses affinity-, ion exchange-, and size-exclusion columns. Using a multistep purification scheme removes the manual steps that cause loss of precious proteins and take more time, like dialysis, collection, and reinjecting samples. The final purification scheme reduces a 3–4-day process to 11.5 h from start to finish, all while improving reproducibility, yield, and comparable purity.
Click the title above to open The Column September 2018 North American issue, Volume 14, Number 9, in an interactive PDF format.
Click the title above to open The Column September 2018 Europe & Asia issue, Volume 14, Number 9, in an interactive PDF format.
Click the title above to open The Column September 12, 2017 Europe & Asia issue, Volume 13, Number 13, in an interactive PDF format.
Let’s first properly define carry-over in the context that I’d like to discuss here. An injection is made and a chromatogram obtained. On injecting a “blank” as the next injection, one or more of the components of the previous injection appear in the “blank” chromatogram.
I just finished a 10-month stint as Interim Associate Dean for Research and Development in the College of Science at The University of Texas Arlington. I was afforded that opportunity when some restructuring in another college left a temporary vacancy, which I was asked to fill. I certainly considered it an honor to be asked to serve in that role, but the temporary nature of that role also piqued my interest. For me, it seemed like a chance to do an internship in administration, to see if I liked it or not. I worked with great people, I did not really like the role.
Click the title above to open the LCGC Asia Pacific September 2018 regular issue in an interactive PDF format.
Click the title above to open the LCGC Europe September 2018 regular issue in an interactive PDF format.
The recent relocation of a laboratory yielded a number of insights as to how to ensure a quality environment to deliver quality gas separation and detection within a safe working atmosphere.
Various strategies to improve LC-MS sensitivity in order to enhance signal-to-noise ratio, and help you realize the hidden potential of this method are discussed.
This article describes and tests a dynamic DHS−TD−GC−MS method for the fingerprinting analysis of mobile volatile organic compounds in soil.
In the first of a three part series, we discuss challenges associated with successful transfer of chromatographic methods and how to best circumvent and remove ambiguities and contradictions
The final part of the series discusses the importance of an open culture, training, and monitoring metrics in the establishment and support of a regulated laboratory.
Column-based liquid phase separation techniques, such as liquid chromatography (LC) in reversed phase separation mode and capillary electromigration techniques, using continuous electrolyte systems, are widely used for the identification and quantification of phenolic compounds in plants and food matrices of plant origin. This paper is the first of a two-part review article discussing fundamental and practical aspects of both LC and capillary electromigration techniques used for the analysis of phenolic compounds occurring in plant-derived food and in edible and medicinal plants. The chemical structure and distribution of the major phenolic compounds occurring in the plant kingdom, as well as the main methods used for their extraction and sample preparation, are also discussed. Part 1 will focus on liquid chromatography.
Several new materials and columns have been introduced in recent years for size-exclusion separations of proteins. How do I know which one to choose, and which separation conditions will be the best for my protein separation?
Click the title above to open the LCGC North America September 2018 regular issue in an interactive PDF format.
The quality of a gas chromatogram depends heavily on the quality of the separation and detection gases, among many other factors. In this month’s instalment, “GC Connections” discusses ways in which chromatographers can ensure a safe working environment while delivering gases that are up to the requirements of the separations at hand, in the context of moving a laboratory to a new location.
This is the second of three articles looking at the impact of the new United States Pharmacopeia (USP) on analytical instrument qualification (AIQ) on data integrity in a regulated chromatography laboratory. This part focuses on how the laboratory should supervise the execution of operational qualification (OQ) protocols by a third-party service provider. The principles described also apply to in-house metrology departments.
Liquid chromatography–mass spectrometry (LC–MS) has become the preferred analytical technique for many challenging assays based on its selectivity, sensitivity, and broad applicability to compounds of varying polarity. Despite its advantages, the complexity of LC–MS systems often leaves analysts struggling to meet method detection limits. In this instalment of “Column Watch”, several strategies will be discussed to improve method sensitivity through the reduction of contaminants, the careful selection of LC method conditions, and the optimization of MS interface settings. By understanding the relationship between these parameters and ionization efficiency, analysts can enhance their signal-to-noise ratio and realize the hidden potential of their LC–MS.
The 38th International Symposium on the Purification of Proteins, Peptides and Polynucleotides (ISPPP 2018) will be held on November 4–7 2018 in Berlin, Germany.
Column-based liquid phase separation techniques, such as liquid chromatography (LC) in reversed phase separation mode and capillary electromigration techniques, using continuous electrolyte systems, are widely used for the identification and quantification of phenolic compounds in plants and food matrices of plant origin. This paper is the first of a two-part review article discussing fundamental and practical aspects of both LC and capillary electromigration techniques used for the analysis of phenolic compounds occurring in plant-derived food and in edible and medicinal plants. The chemical structure and distribution of the major phenolic compounds occurring in the plant kingdom, as well as the main methods used for their extraction and sample preparation, are also discussed. Part 1 will focus on liquid chromatography.
While capillary gas chromatography has been undergoing a renaissance, with new columns, detectors, data systems, and multidimensional separations, the classical inlets have remained the same: We are still injecting liquid samples with syringes into split and splitless inlets, as we have for nearly 50 years. Split and splitless injections present several well-known and some not-so-well known challenges, mostly arising from heating of the inlet, that make sample injection and inlets a major hurdle for gas chromatographers. These challenges and some ideas for mitigating them are discussed and a case is made for renewed exploration of the cool inlets and injection techniques: cool on-column and programmed temperature vaporization.
