Enhancing PLGA Characterization with Multi-Angle Light Scattering and Differential Viscometry
September 21st 2018The 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.
Automated Multicolumn Purification of a Histidine-Tagged Protein
September 21st 2018Approximately 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.
The LCGC Blog: Solve Carryover Problems in Gas Chromatography
September 11th 2018Let’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.
The LCGC Blog: Analytical Chemistry is Central to All Modern Research
September 5th 2018I 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.
Instrument Considerations in the Transfer of Chromatographic Methods, Part I: Method Considerations
September 1st 2018In 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
Safely Delivering the Best Possible Carrier and Detector Gases to Your GC System
September 1st 2018The 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.
Data Integrity and USP , Part 2: OQ Supervision and Execution
September 1st 2018This 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.
LC–MS Sensitivity: Practical Strategies to Boost Your Signal and Lower Your Noise
September 1st 2018Liquid 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.