Investigation of Reequilibration in Hydrophilic Interaction Liquid Chromatography
December 1st 2016Interest in chromatography using hydrophilic interaction liquid chromatography (HILIC) has continued to build in recent years. Adoption of the technique has been slowed by experiences of poor reproducibility. In particular, reequilibration times in HILIC have been reported as being exceptionally long as compared to reversed-phase chromatography. In this study, reequilibration times in HILIC for both aqueous–organic gradients and buffer gradients are systematically explored. The results not only promise to improve method development practices, but also provide insight into HILIC retention mechanisms across mechanistically differing polar stationary phases.
Analysis of Synthetic Opiates and Novel Analgesics in Urine Using SPE and HPLC–MS/MS
December 1st 2016Opiate abuse is drastically on the rise in the United States. In addition to traditional naturally occurring opiate compounds, forensic toxicologists also need to be able to rapidly identify synthetic opioid-like drugs. A rapid, three-step solid-phase extraction (SPE) procedure for the identification and quantification of fentanyl and its major urinary metabolite norfentanyl, in addition to four “designer” compounds, U-47700, W-18, W-15, and furanyl fentanyl, is presented here. As a result of the rapid use and abuse of fentanyl in medical and recreational settings, respectively, it is important to develop a method that can accurately extract this Schedule II drug from any other novel compounds that may be present.
Identifying EDCs in Paper Mill Wastewaters
December 1st 2016Researchers investigating paper mill effluents and their impact on surface waters in Slovenia have identified endocrine disrupting compounds (EDCs) and their mutagenic and genotoxic properties using gas chromatography–mass spectrometry (GC–MS).
Tips & Tricks GPC/SEC: Polydispersity — How Broad is Broad for Macromolecules?
December 1st 2016The vast majority of macromolecules exhibit a molar mass distribution that is often described by the polydispersity index (PDI). This Tips & Tricks instalment offers practical advice to consider when analyzing macromolecules using liquid chromatography (LC).
Label-Free Characterization of the Reversible Self‑Association of Insulin
December 1st 2016The degree and strength of self-association are critical quality attributes for insulin and its analogues. In this article we present the label-free determination of these quantities using composition-gradient multi-angle light scattering (CG-MALS), enabling the formulation of engineered insulin optimized for stability and efficacy.
Optimizing SEC for Protein Characterization
December 1st 2016The 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.
Nasal Spray Evaluation Using Thin Layer Chromatography
November 17th 2016Research on nasal spray formulation has yielded an improved in vitro analytical test method utilizing thin layer chromatography (TLC). The research used simulated nasal mucus with varying properties and a TLC apparatus to assess the dripping behaviour of nasal formulations to improve the nasal spray development process.Nasal Spray Evaluation Using Thin Layer Chromatography