The Column-06-11-2018

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The Column

While gel permeation chromatography/size-exclusion chromatography (GPC/SEC) of uncharged molecules in organic eluents in most cases is a straightforward task, aqueous GPC/SEC of polyelectrolytes usually requires more parameters to be considered and optimized. This instalment of Tips & Tricks explains more.

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Metabolomics, a word coined in 1998, is the study of small molecules (that is, organic chemicals with a molecular weight of 50–2000 Daltons) present in a given biological fluid, tissue, organ, organism, and environment at a given time. Using the power and high throughput of analytical platforms, such as mass spectrometry (MS) or nuclear magnetic resonance (NMR) spectroscopy, metabolomics promises to be a cornerstone in innovations and discoveries in the areas of medicine, agriculture, biomedical, space, and environment. Thus, science, technology, engineering, and mathematics (STEM) graduates and doctorates who interface with analytical chemistry need to prepare for the challenges of academia or industry as metabolomics research takes a centre stage in this big data era.

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Ethylene glycol is a particularly difficult compound to analyze because it is not easily extracted from water. Many environmental samples originate from water runoff at airports, where ethylene glycol is used as a de‑icing agent for airplanes during winter months. Hydraulic fracturing is a technique where pressurized fluid and sand or other solids (proppant) are used in gas drilling to allow gas extraction. Glycols are a common ingredient in most hydraulic fracturing fluid and play a key role in preventing emulsifications and stabilizing the solutions. The direct aqueous injection of ethylene glycol is challenging because it can be difficult to attain reproducibility and good peak shape. The large expansion volume of water can cause backflash, carryover can cause inconsistent results, and excess water can extinguish the flame ionization detection (FID) flame. This article describes a robust approach to analyze glycols in aqueous samples, which reduces downtime and maintains sensitivity.

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Peak intensity enhancement is one highly desirable outcome of comprehensive two-dimensional gas chromatography (GC×GC). When coupled to mass spectrometry (MS), such enhancement is usually achieved with a thermal modulator using a technique called cryogenic zone compression (CZC). Differential flow modulation is a simple and cost-effective alternative to thermal modulation, but the requisite high flow rates are generally perceived as being incompatible with most (electron ionization [EI] and chemical ionization [CI]) mass spectrometers. The past decade has witnessed resurgent interest in coupling GC to atmospheric pressure chemical ionization (APCI), which requires high gas flows to assist ionization. This article reports on the modification of a GC–APCI system with a flow modulator and evaluates its potential to enhance the sensitivity towards selected trace organics.

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Josef Heiland has been awarded the 2018 Eberhard Gerstel Prize for his publication “Temperature Gradient Elution and Superheated Eluents in Chip-HPLC” (1), which was published in the journal Analytical Chemistry.

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Analyzing drugs of abuse (DoA) in human bodily fluids is crucial for clinical research and forensic toxicology. In these routine analyses, a large number of samples must be investigated, with a potentially high laboratory cost for each sample. As such, a reliable and affordable method is required for analysis. In this article, a fast, robust, and reliable method is presented for routine, high-throughput drug screening of urine samples.

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LabConnect LLC, a global provider of central laboratory and support services for biopharmaceutical, medical device, and contract research organization, has completed phase one of a 11,000 square foot facility expansion in Johnson City, Tennessee, USA.