Gel permeation/size-exclusion chromatography (GPC/SEC) is the standard method for separating samples by molecular size and determining molar mass distributions. However, GPC/SEC instruments can also be used to investigate porous materials and to learn more about pore size distributions, as a powerful alternative to nitrogen gas (N2) adsorption or mercury (Hg) intrusion porosimetry.
Contaminants in surface water and drinking water supplies arising from pharmaceutical and personal care product use as well as other compound sources pose a difficult challenge for analytical chemists. Thomas Letzel from the Technical University of Munich in Germany, spoke to The Column to discuss collaborative research taking place in Europe to address contaminants of emerging concern in water analysis.
Researchers from Imperial College London and the University of Aberdeen have identified disease markers for Human African Trypanosomiasis (HAT), commonly known as “sleeping sickness”. Using reversed-phase ultrahigh‑performance liquid chromatography coupled to mass spectrometry (UHPLC–MS) and proton nuclear magnetic resonance (1H NMR) spectroscopy researchers found 53 discriminatory metabolite markers.
Sciex (Framingham, Massachusetts, USA) has announced a co‑marketing agreement with Pressure BioSciences, Inc. (South Easton, MA, USA), which aims to address the challenges arising in complex sample preparation.
Crawford Scientific (Strathaven, UK) has announced that it will become YMC Europe’s (Dinslaken, Germany) sole authorized distributor within the UK.
A glimpse of what’s on offer for chromatographers at Pittcon 2016, which will be held from 6–10 March 2016 at the Georgia World Congress Center in Atlanta, Georgia, USA.
The key variables and instrument setup requirements needed to achieve success in gas chromatography–mass spectrometry (GC–MS).
Click the title above to open The Column February 08, 2016 Europe & Asia issue, Volume 12, Number 2, in an interactive PDF format.
Click the title above to open The Column February 08, 2016 North American issue, Volume 12, Number 2, in an interactive PDF format.
A team of researchers based in France has examined the consequences of microwave and electron-beam treatments on food and its packaging using high performance liquid chromatography (HPLC) and gas chromatography (GC)
Click the title above to open the LCGC North America February 2016 Application Notebook Issue, Vol 34 No s2, in an interactive PDF format.
Click the title above to open the LCGC North America February 2016 Chromatography and Sample Preparation Terminology Guide, Vol 34 No s2, in an interactive PDF format.
The winner’s of LCGC’s 9th annual awards are highlighted
Recently several states have legalized recreational and medical marijuana. This has created a confusing set of circumstances due to legalization at the state level, but cannabis is still an illegal schedule 1 drug at the federal level. This confusion also affects the development of analytical methods because there are no clear guidelines available to laboratories. This whitepaper will discuss the following topics: • Overview of state analytical requirements • Discussion of analytical method development for cannabinoids and related compounds of interest • Discussion of method performance
UV technologies are being increasingly used in water purification systems, taking advantage of the germicidal properties of UV and also its effect in reducing organic contaminants. This paper discusses the effectiveness of using UV technologies along a water purification chain and the parameters and configurations to be considered when selecting UV lamps for water purification systems.
Volatile organic compounds (VOCs) are carbon containing compounds that evaporate easily at normal temperatures. They are typically generated from petroleum products, plastics, paints and solvents,. Other sources are the disinfecting agents used to control microbial contaminants in drinking water. Disinfecting agents react with naturally occurring organic matter in the source water to produce VOCs known as trihalomethanes. When VOCs are spilled or improperly disposed of a portion will evaporate, but some will soak into the ground and eventually end up in drinking water supplies
Ion chromatography (IC) has been recognized as one of the most competitive techniques for trace analysis, based on results from continuing research and development work into different types of instrumentation. Ultratrace analysis requires the use of extremely clean reagents, including water. The ionic content of water was monitored by IC along a water purification chain, from tap water to ultrapure water. This study shows that ultrapure water from a Milli-Q system is suitable for trace analysis by IC.
Semivolatile calibrations on this column dimension often range from 1.0 to over 100 ng/µL; however, a 0.25 mm ID column usually experiences peak overload as the mass on column approaches 10 ng. As shown in Figure 1, isobars that elute close together-such as benzo[b]fluoranthene and benzo[k]fluoranthene-quickly become unquantifiable as mass on column increases. Under split conditions, the resolution requirement (50% valley) is met for all nine calibration standards, and the peak apices shift less than 0.04 min, indicating only minor peak overload. Conversely, under splitless conditions, the three highest concentration calibration standards fail the resolution criterion. The peak fronting and resulting overlap from column overload make it impossible to generate a linear calibration including these points. Additionally, the peak apex of benzo[b]fluoranthene shifts more than 0.2 min, which could result in an erroneous compound identification.
Integration of RI peak areas enabled calculation of the AMY:AMP ratios, in excellent agreement with the nominal values. The values for Mw and Rz fall within the generally accepted limits found in the literature. Conformational plots for the AMP component verify its branched nature.
Pavel Jandera spoke to Frantisek Foret about building his own liquid chromatograph, the birth of “modern” high performance liquid chromatography (HPLC), the importance of exploring (and understanding) earlier research papers, current trends in contemporary chromatography, and his inspiring advice for aspiring chromatographers.
Fluorinated stationary phases, especially those including a pentafluorophenyl (PFP) moiety, have become popular alternatives to the more traditional alkyl (C8 and C18) phases. Many modern column lines have, in fact, been initially introduced with the standard C18 and a PFP phase because of their orthogonality. In this instalment, the differences between alkyl phases and PFP phases are discussed in terms of fundamental interactions. The origin of the interactions is also interpreted to better understand how analysts can use and control them to develop effective and rugged analytical methods.
An excerpt from LCGC’s e-learning tutorial on sample preparation troubleshooting at CHROMacademy.com
Click the title above to open the LCGC Europe February 2016 regular issue, Vol 29, No 2, in an interactive PDF format.
Click the title above to open the LCGC North America February 2016 regular issue, Vol 34 No 2, in an interactive PDF format.
Ultrahigh-pressure size-exclusion chromatography (UHPSEC) can potentially offer a new direction and overcome some of the disadvantages (for example, limited resolution and long analysis time) associated with conventional SEC analysis. UHPSEC is based on using sub-3-µm silica-organic hybrid particles under elevated pressures (often above 400 bar) to improve the separation efficiency and increase analysis speed. In spite of the benefits promised by the chromatographic theory, there are some uncertainties that may limit the proliferation of UHPSEC in polymer analysis. As a result of possible issues associated with the use of a different stationary phase - including secondary interactions and polymer degradation - it is unclear whether UHPSEC will provide results comparable to those of traditional SEC methods. In this article, the advantages and challenges of UHPSEC for the analysis of different engineering thermoplastics are discussed, as well as a comparison of results obtained with UHPSEC and conventional SEC.
A glimpse of what’s on offer for chromatographers at Pittcon 2016, which will be held from 6–10 March 2016 at the Georgia World Congress Center in Atlanta, Georgia, USA.
This is the third “LC Troubleshooting” column in a series related to problems that we associate with liquid chromatography (LC) columns. This month is the first of several discussions looking at problems that are caused by chemical problems with the column.
Mark Schure spoke to LCGC Europe’s Lifetime Achievement Award winner, Hernan Cortes, about his career with Dow Chemical, multidimensional chromatography, the evolution of mass spectrometry (MS), and the direction that liquid chromatography (LC) is taking.
Thermal desorption sampling often provides a means for bringing otherwise intractable samples to a gas chromatography (GC) column for separation and detection. In this instalment, John Hinshaw describes the principles of thermal desorption sampling in relationship to other analysis techniques for volatile solutes.
Cloud-point extraction (CPE) manipulates temperature and surfactant concentration to move aqueous solutes into a micelle phase for separation. Although CPE has been around for some time, it is still considered an emerging technique. Much of the development, and most applications, of CPE have dealt with extraction and preconcentration of inorganic solutes. More recently, attention has turned to the use of CPE in the isolation of organic solutes. This month, we review how CPE works and focus on applications for extracting organics.
