Liquid Chromatography (LC/HPLC)

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.

I remember reading a study on learning in the all-day short-course format. Because teaching liquid chromatography (LC) classes is a significant part of my work, my attention was captured. The writers claimed that in a 6–8 h class, only three points would be remembered. One of my LC troubleshooting classes has approximately 200 slides - what does this say about how effective a short course is at conveying critical knowledge? As the saying goes, I have tried to make lemonade out of these lemons, and use the "only three things" concept to help reinforce what I think are the key points. So, this month's "LC Troubleshooting" instalment will use these points to form the core of a preventive maintenance programme for your LC system.

Waters Corporation (Milford, Massachusetts) has unveiled its new brand showcase celebrating the achievements of customers and their scientific advancements made possible with Waters technology.

Nysa Membrane Technologies, Inc., announced Natrix Separations, Inc. as the company's new name.

Ronald E. Majors, a senior chemist at Agilent and LCGC's "Column Watch" and "Sample Preperation Perspectives" columnist, received the Chromatographic Society?s 2007 Martin Gold Medal at HPLC 2008.

Researchers conducting clinical research trials of patients with bladder cancer have discovered a non-invasive way to detect the cancer by using HPLC/MS.

The Pittsburgh Conference announces the launch of its 2009 website, www.pittcon.org, containing relevant information for conferees and exhibitors about Pittcon 2009 which will be in Chicago, Illinois, McCormick Place, March 8 -13, 2009.

Agilent Technologies Inc. (Palo, Alto, California) announced it has acquired substantially all of the assets of Taiwan-based Escort Instruments Corp., an established supplier of low-cost test and measurement instruments and a subsidiary of Unitech Printed Circuit Board Corp.

What do you do when the method can't be reproduced?

Many HPLC analyses could be performed at lower expenditure. This could involve a combination of reducing the analysis time, reducing the resolution between critical peaks, and lowering the consumption of mobile phase. Successfully optimizing the method in such instances - as well as in situations where it is necessary to transfer the method to another laboratory that lacks the same selection of columns - can save the analyst time and money.

This article investigates the different methods that can be used to compare the performance of liquid chromatography (LC) columns to assess the advantage of using them at high pressures and/or high temperatures. The main focus is on the kinetic plot method. This method, which is based on two simple equations, allows the user to transform the more common Van Deemter curve into a curve describing the ultimate separation speed as a function of the required plate number, or the required peak capacity or the required resolution.

John Dolan has discovered that check-value problems have jumped to the top of the list with LC users. He takes a look at them in this month's installment of "LC Troubleshooting."

Guest columnsist and LCGC Emerging Leader award recipient Gert Desmet considers the different methods that can be used to compare the performance of LC columns.

Thermo Fisher Scientific Inc., the world leader in serving science, announced that they have been presented with two 2008 Frost & Sullivan Best Practices awards for Market Leadership and Competitive Strategy Leadership in Informatics.

In the first reported study of skeletal muscles in hibernating creatures by two-dimensional gel electrophoresis (2-DE), scientists from Korea have attempted to shed some light on the molecular processes behind atrophy prevention.

Scientists in China have devised a GC-ECD procedure that involves bromination of acrylamide to give a derivative that is more easily detected at low levels than acrylamide itself. Their research comes in response to the discovery of acrylamide in many types of cooked food in 2002. This discovery made news due to the link between acrylamide and cancer. From a scientific point of view, the acrylamide discovery ensured the creation of a new generation of research grants, many of which involve mass spectrometry, using GC?MS or LC?MS.