Liquid Chromatography (LC/HPLC)

Micellar liquid chromatography (MLC) is a reversed-phase liquid chromatographic mode with a solution of surfactant forming micelles as the mobile phase. The interaction of solutes with the stationary phase coated with surfactant monomers, combined with the increased solubilization capability of micelles, have profound implications with regard to retention, selectivity and efficiency. Practical steps that a chromatographer involved in MLC should consider when developing an analytical procedure are described, including mobile phase preparation, column conditioning and cleaning.

The move from conventional particle sizes (5 μm or higher) to smaller diameter packing materials is one of the most attractive approaches to achieve higher separating efficiency. Recently developed 3 μm polysaccharide-derived chiral stationary phases demonstrate characteristics of favourable mass transfer kinetics, high column efficiency and good column permeability. This allows the fast analysis of enantiomers using conventional HPLC instruments.

The National Center for Research Resources, a branch of the National Institutes of Health, has granted the University of Wisconsin- Madison a $1.6 million federal grant to purchase a mass spectrometer, a nuclear magnetic resonance spectrometer, and a liquid-chromatography system, integrated into a single instrument.

JASCO and Princeton Chromatography have announced a collaboration in the areas of Supercritical Fluid Chromatography (SFC) instrumentation and column manufacturing.

Scientists from Taiwan have developed a method for dispersive liquid-liquid microextraction of ionisable compounds that renders it compatible with reversed-phase HPLC by combining it with in-syringe back extraction. The new system was demonstrated with the removal of the drug clenbuterol from water.

Currently papers are being accepted for the 9th Csaba Horvath Medal Award Symposium to be held on April 28-29, 2009 at the Hartford Convention Center in Hartford, Connecticut.

HPLC 2008 was held in Baltimore in May. Columnist Ron Majors covers the highlights of this major symposium, held in the U.S. every two years.

After returning from Israel, John Dolan dedicates this month's column discussion to three problems that know no international boundaries: how to condition a new column, the effect of washing a column with water, and ...

Advanced Materials Technology (Wilmington, Delaware), a manufacturer and developer of columns for HPLC, and the Berlin-based Capsulution NanoScience AG signed a license contract for the use of the LBL? Technology in June.

Quantum Analytics (Foster City, California) and LEAP Technologies (Carrboro, North Carolina) have announced a co-marketing partnership to offer efficiency improving chromatography and mass spectrometer systems, including new developments in front-end automation.

Nanostream, Inc. (Pasadena, California), a developer of microfluidics-based parallel HPLC technology and a provider of assay development has closed all business operations.

FEI Co. ( Hillsboro, Oregon), a manufacturer of high-resolution imaging and analysis technology, has signed Shimadzu Corp (Kyoto, Japan), a leading provider of analytical instrumentation, as its sales agent in Japan.

Ameritox, Ltd. (Midland, Texas), a U.S. leader in pain prescription urine drug monitoring, announced its addition of an LC-MS-MS method for detecting prescription pain medications.

The analysis of polar compounds in support of clinical and preclinical pharmacokinetic studies requires an analytical methodology capable of achieving ultra-low detection and quantification limits. The high sensitivity afforded by coupling HPLC with tandem mass spectrometry (MS–MS) has made it the technique of choice in this environment, but it is subject to the following limitations when reversed-phase liquid chromatography (RPLC) is used

An effective UHPLC–MS method for high throughput separation, identification and quantification of pseudoephedrine was developed on a Hypersil GOLD PFP 1.9 µm, 2.1 Ã- 100 mm column.

Several common birth control formulations contain both drospirenone and ethinyl estradiol. A highly selective and sensitive analytical method for the analysis of drospirenone in human plasma has been developed for use in bioequivalence studies. The solid-phase extraction (SPE) and UPLC–MS–MS methodologies are described as well as performance against validation parameters.

In March 2007, several North American manufacturers of pet food voluntarily issued nationwide recall notices for some of their products that were reportedly associated with renal failure in pets. The raw material wheat gluten, used to manufacture the pet food, was imported from China and was identified as the source of contamination.

This application note describes a fast and sensitive LC–MS method using a Hypersil GOLD column on a Thermo Scientific LC–MS system for the quantitative analysis of two widespread PFCs, perfluorooctanoic acid (PFOA) and perfluorooctansulphonate (PFOS).

Ramipril impurities D and E are well-known degradation products of ramipril in the finished dosage form. A significant amount of an additional impurity was detected in ramipril tablets by an isocratic reversed-phase high performance liquid chromatography (HPLC) method on a short column. The structure of this impurity was proposed based on liquid chromatography–mass spectrometry (LC–MS) data using an electron spray ionization source. Structural elucidation using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy was facilitated by a newly developed preparative isolation method. This impurity was characterized as (2R,3aR,6aR)-1-[(R)-2-[[(R)-1-(ethoxycarbonyl)-3-phenylpropyl]amino]propanoyl]octahydrocyclopenta[b]pyrrole-2-carboxylic acid (impurity L). Its identification, synthesis and characterization are discussed.

Automated solid-phase extraction (SPE) has been used extensively with liquid chromatography–tandem mass spectrometry (LC–MS-MS) to facilitate high-throughput analysis in the pharmaceutical, diagnostic, and forensic toxicology areas. In this work, we demonstrate the use of a systemized approach to SPE method development and LC–MS-MS analysis. This approach provides dramatic savings in analysis time and takes advantage of new innovations in high performance liquid chromatography (HPLC) columns to provide the cleanest extracts for LC–MS injection.

The authors meet the need for a method for the determination of cytosine purity by developing a hydrophilic interaction chromatography (HILIC) method with demonstrated advantages in comparison to other separation techniques.

This month's column will consider two problem areas; peaks that have severely tailing peaks, or split or doubled peaks, and the peaks that front badly.

Liquid chromatography with tandem mass spectrometry (LC–MS-MS) led to a revolution in environmental testing. The coupling of liquid chromatography with tandem mass spectrometry created a powerful analytical tool for the analysis of emerging environmental contaminants. Pharmaceuticals and personal care products, perfluorinated compounds, brominated flame retardants, and disinfection byproducts were chosen as examples to illustrate the use of this new technique in environmental analysis.

Guest Editor Peter Schoenmakers provides an introduction to LCxLC, and then goes on to talk about peak capacity, sample dimensionality, phase orthogonality, and some of the successes of the technique and the obstacles yet to be overcome.

In gradient mode, the quality of the analysis will be influenced by the performance of the proportioning and mixing of the eluents at any time during a given chromatogram.