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.
The silica-based packing in reversed-phase columns is not inert. Here we consider what happens when the mobile-phase pH is too high or too low.
Data integrity issues are changing the way that we should be undertaking computerized system validation (CSV) of our chromatography data systems (CDSs). Do you understand what is required in the brave new world of CSV?
The selectivity of different combinations of organic modifiers, pH, and types of reversed-phase liquid chromatography (LC) materials has been characterized using Tanaka column characterization, linear solvent energy relationships (LSER), and selectivity correlations. The three characterization techniques highlighted the potential complementary selectivity of these phases and conditions as well as the type and dominancy of some of the retention mechanisms involved. Subsequently, selectivity differences were proven to be valid in the practical separation of acids, bases, and neutral analytes. This paper aims to assist chromatographers in producing highly efficiency method development strategies for reversed-phase LC separations in a relatively short time frame.
Since their beginnings in 1986, UCT has evolved into a major competitor in the field of silica based solid phase extraction technology. The first to pioneer commercially available ‘mixed-mode’ SPE products, 30 years later UCT is still optimizing sample analysis for forensic, pharmaceutical, clinical, environmental and agricultural laboratories. Michael J. Telepchak, founder and CEO UCT, Inc., has laid the foundation for this powerful technology and has truly served as a catalyst for its transformation from a novel technique to an industry gold standard. From fundamental chemistry to manufacturing and business development, he has bared witness to all facets of the evolution of solid phase extraction and will speak on the monumental impact it has made on the scientific community.
Since their beginnings in 1986, UCT has evolved into a major competitor in the field of silica based solid phase extraction technology. The first to pioneer commercially available ‘mixed-mode’ SPE products, 30 years later UCT is still optimizing sample analysis for forensic, pharmaceutical, clinical, environmental and agricultural laboratories. Michael J. Telepchak, founder and CEO UCT, Inc., has laid the foundation for this powerful technology and has truly served as a catalyst for its transformation from a novel technique to an industry gold standard. From fundamental chemistry to manufacturing and business development, he has bared witness to all facets of the evolution of solid phase extraction and will speak on the monumental impact it has made on the scientific community.
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).
Some modern HPLC systems resemble spacecraft in terms of their technology, designed as they are to operate to the highest efficiencies, compared to traditional systems.
A fully tested LC-MS/MS workflow for rapid and robust quantification of more than 250 pesticides below maximum residue limits (MRLs) with sensitivity, accuracy, and precision that meets stringent EU guidelines.
The use of ion-exchange sorbents for the preconcentration, separation and determination of metal ions is well established in the literature. Selection of an appropriate sorbent ensures both high efficiency in metal chelating while minimizing the mass of sorbent required for a particular analytical task. A high efficiency sorbent means that a smaller bed mass may be used thereby reducing the quantity of solvent required for elution yielding greater analytical sensitivity.
New research into flow modulation methods in valve-based two-dimensional gas chromatography (GC×GC) has produced an effective alternative to traditional pulse modulation.1 Described as “pattern modulation”, this new method increases effluent to the secondary column with flow rates compatible with most chromatographs and spectrometers.
Summary of the Eastern Analytical Symposium 2015.
A detection method for early-stage ovarian cancer has been developed using ultrahigh‑pressure liquid chromatography–high-resolution mass spectrometry (UHPLC–HRMS) in combination with tandem MS–MS.
Incognito talks about reproducibility in research.
The inherent sensitivity and selectivity of time-of-flight mass spectrometry (TOF-MS) can be augmented by soft electron ionization (EI) to provide ultratrace-level quantitation of organotins in complex environmental extracts. These organotin species are a focus of current concern as environmental contaminants, but analysis using conventional 70 eV ionization energies is made difficult by their propensity to undergo extensive fragmentation. The use of soft EI helps to solve this problem by producing simplified spectra with enhanced diagnostic ions.
Column overload is a very commonly encountered issue in gas chromatography (GC) for beginners. Changes in peak symmetry, generally observed as peak fronting, can be subtle in the sharp peaks generated by GC, but the result can be significant shifts in retention times, loss of resolution, and error in peak integration. LCGC Blogger Kevin Schug explains more.
A review of the 10th Balaton Symposium on High-Performance Separation Methods, which was held 2–4 September 2015 at the Hotel Azúr, Siófok, Hungary.
Click the title above to open The Column January 19, 2016 Europe & Asia issue, Volume 12, Number 1, in an interactive PDF format.
Click the title above to open The Column January 19, 2016 North American issue, Volume 12, Number 1, in an interactive PDF format.