In the previous installments of this series on efficient development of LC methods (1?5), we have concentrated on improving resolution by modifying the mobile phase, choosing a different stationary phase, or changing some other condition, such as column temperature. In this month?s "LC Troubleshooting" installment, we take a look at trading some of that resolution for a faster separation.
In this installment of "Column Watch," columnist Ron Majors examines the role of pressure in high performance liquid chromatography (HPLC) from two viewpoints: the impact of the ultrahigh pressures encountered in ultrahigh-pressure liquid chromatography (UHPLC) on chromatographic parameters and increases in column pressure encountered in normal daily use. The latter is of more practical consequence to HPLC users since increased back pressure usually implies that something has gone wrong with the column. Pressure increases due to physical and chemical contamination are explored and practical approaches to solve these problems are suggested.
Basic information on stereochemistry is provided in this article to help readers develop a better understanding of the separation mechanisms that come into play in various separation methods used for chiral compounds. This knowledge can allow readers to select a desirable chiral separation method, based upon the molecular structure of the chiral compound of interest. Logical reasons for the selection process are discussed later in this article.
Faster isn't always better.
High performance liquid chromatography–solid phase extraction–nuclear magnetic resonance (HPLC–SPE–NMR) is a novel hyphenation technology that concentrates single chromatographic peaks to elution volumes matching those of NMR flow probes. The SPE unit facilitates the solvent exchange from the mobile phase of the optimized HPLC assay to a deuterated NMR solvent. The well-defined NMR solvent conditions make spectra comparisons feasible, which means databases and spectra catalogues can be used to swiftly identify analytes. The ability to accumulate analytes on the SPE cartridges by multiple trapping reduces the need to perform residual solvent suppression experiments and allows heteronuclear NMR experiments to be performed overnight. Structure elucidation of natural products directly from crude extract HPLC samples has become the key application of this technique.
This month, Chromatography Online's Technology Forum looks at the topic of HPLC/TLC and the trends and issues surrounding it. Joining us for this discussion are Eike Reich from Camag, Gerda Morlock, from University of Hohenheim, and Colin poole, from Wayne University.
Polymer-based columns still are widely used in size-exclusion chromatography (SEC) and ion chromatography-ion-exchange chromatography - they have always been used in these modes, even back in 1987.
The unique features of silica hydride-based columns are described with a focus on how these columns can expand a laboratory's capabilites in HPLC and LC-MS. Of particular interest is the ability to retain both polar and nonpolar compounds and provide an orthogonal method of analysis for currently existing procedures.
Shimadzu Scientific Instruments (Columbia, Maryland) and Groton Biosystems (Boxborough, Massachusetts) recently announced a collaboration effort to interface Groton’s online sampling monitors with Shimadzu’s high performance liquid chromatography (HPLC) system to form a closed-loop solution for online analysis.
Gilson, Inc. (Middleton, Wisconsin), an industry leader in purification systems for high performance liquid chromatography (HPLC), solid phase extraction (SPE), and gel permetation chromatography (GPC) clean-up, now offers direct support and sales in the United States.
Thermo Fisher Scientific Inc., a leader in the separation sciences and chromatography industries, announces the launch of its enhanced partner program. The program is designed to support the expansion of the companies' informatics activity via its partners around the globe, the world class program will utilize business partners to better meet customer needs in multiple industries. Thermo Scientific?s informatics offerings include laboratory information management systems, chromatography data systems, and spectroscopy software.
This article describes the factors that affect the selection of columns for two-dimensional (2D) LCÃ-LC separations. The maximum increase in peak capacity compared with single-dimension (1D) separations is obtained by using "orthogonal" systems employing various combinations of separation mechanisms to provide as different separation selectivities as possible for the sample compounds in the first and in the second dimension systems. To obtain best results, matching the chemistry of the stationary phase, column dimensions and mobile phases in the first and in the second dimensions is essential for successful separations, especiall for comprehensive LCÃ-LC.
Getting started on the right foot is important for efficient method development.
How to avoid an expensive shot in the dark.
An ultrahigh-pressure liquid chromatography (UHPLC) method was developed to separate paroxetine from several of its related compounds using a systematic screening protocol that monitors combinations of selectivity factors including column chemistry, organic modifier, and pH. When the best combination of these factors was selected, the method was optimized by varying gradient slope and temperature.
HPLC 2007 was held in Ghent, Belgium in June. Last month, columnist Ron Majors summarized some the important column developments as well as other Symposium highlights. This month, he winds up coverage with additional highlights in the areas of technology and applications. Among the topics covered are stationary phase preparation and characterization, multi-dimensional and comprehensive LC, temperature studies, detectors and an application overview.
This report shows the steps involved in the development of a new polymethyl methacrylate (PMMA) calibration standard for polar organic GPC applications.
The Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, an event that features the newest applications and technologies in the chromatography industry, have announced the 2008 Pittsburgh Conference Memorial National College Grants (PCMNCG) Program.
Eksigent, a developer of advanced low-flow fluid delivery liquid chromatography technologies, announced distribution agreements with three companies in Europe for sales and service of the company's high performance liquid chromatography (HPLC) and liquid chromatography (LC) product lines.
Leipziger Messe, organisers of L.A.B. - the trade fair and conference devoted to analysis, bio and laboratory equipment - have announced that the show will host 88 exhibitors from countries including the UK, US, France, Italy, Finland, the Netherlands, and Germany. L.A.B. takes place from 2-4 October 2007 at ExCeL London.
Ronald E. Majors, LCGC North America columnist and Senior Chemist for the Columns and Supplies Division of Agilent Technologies, Inc., has been awarded the 2007 Martin Gold Medal by the Chromatographic Society in the United Kingdom for outstanding contributions to the chromatography field.
Waters Corporation (Milford, Massachusetts) and Lambda Therapeutic Research Ltd (Mumbai, India) recently announced a joint cooperative agreement that provides innovative analytical laboratory equipment designed to enhance research quality service and business solutions for Lambda and its clients.
Science Daily, a website that features news revolving around the sciences, has published an article that describes new chromatographic techniques for the analysis of pesticides and antibiotics in food and beverage samples.
Applied Biosystems (Foster City, California) recently announced three new value-added services for laboratories that are utilizing Applied Biosystems/MDS SCIEX mass spectrometry (MS) instrument systems as part of an overall workflow solution.
Nanostream, provider of products and services that increase productivity in laboratories at pharmaceutical and biotech companies, extends its global reach to Europe by establishing a sales and support office in The Netherlands.
