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The Integration of Microextraction Packed Sorbent (MEPS) into Multidimensional StratagiesLC–GC approaches to analysis are particularly attractive because they combine the selectivity of solid phase sorbents in the first dimension with the separating power and peak capacity of a capillary GC column in the following dimensions. Their widespread use is limited because of the difficultly in desolvating the stream from the LC dimension without the solvent vapour passing down the GC column in significant quantity. An alternative approach to elution chromatography in the first dimension is to harness the specificity of the solid-phase process for digital chromatography using discontinuous changes in solvent polarity. Digital chromatography on a small sorbent bed reduces the volume of mobile phase to discrete plugs that are sufficiently small to be injected directly into a GC with a large volume injector or, alternatively, subsampled into a conventional split/splitless injector.
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Comprehensive Analysis of Human Plasma Using Gas Chromatography–High Resolution Time-of-Flight Mass Spectrometry: A Workflow to Leverage Electron and Chemical IonizationGas chromatography with electron ionization and mass spectrometry (GC–EI-MS) detection is a workhorse among analytical techniques in metabolomics. A major challenge in the utilization of GC–EI-MS in metabolomics is the identification of unknowns.
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Determination of Geosmin in Water Samples Using Person-Portable GC–MS and Sample Preparation InstrumentsTorion Technologies Inc.
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Inside the Personalized Medicine Toolbox: GCxGC-Mass Spectrometry for High-Throughput Profiling...The authors present results that suggest that high-throughput, high-coverage profiling capabilities, such as those afforded by GCxGC-TOF-MS, can impact the development of personalized medicine.
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Enantiomeric Separation of Proton Pump Inhibitors Using Polysaccharide-Based Chiral Stationary Phases in Reversed-Phase HPLC ConditionsThe chiral analysis and purification of proton pump inhibitors (PPIs) has become a popular topic as more of these drugs fall out of patent protection each year. Due to their wide range of enantiomeric selectivity, a set of polysaccharide-based chiral stationary phases (CSPs) was screened to identify methods for the successful enantioseparation of four benzimidazoles; rabeprazole, lansoprazole, omeprazole, and pantoprazole.
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The Use of Accurate Mass and MS-MS for the Analysis of PPCPs in WaterThe United States Geological Survey (USGS) has found pharmaceuticals and personal-care products (PPCPs) containing known or suspected endocrine-disruptors in U.S. rivers. As such, it is important to use adequate techniques to help identify these compounds and possible metabolites.
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Metabolic Profiling of Peanut Plant Material by LC–TOFMSThere has been an increasing interest in the presence and availability of compounds in plant materials that may possess bioactive properties, in particular, antioxidant activity. Some of these compounds have been attributed to possess anticancer, antiaging, and antimutagenic properties as well as other health benefits (1). The types of plants that have been investigated cover a vast range from common foodstuffs to regional or exotic materials. Plant parts under study have included portions that are traditionally known to be edible, as well as sections that are considered "waste" or used for animal forage. Because most screening techniques involve lengthy separations, high throughput HPLC methods are desirable.
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Stability of Formic Acid in Methanol Solutions and the Implications for Use in LC–MS Gradient Elution AnalysisDilute formic acid solutions in methanol were found to decline in acid content with time, the extent of the decline depending upon the initial amount of water present in these solutions. The effect of the formic acid concentration change upon the separation of peptides using high performance liquid chromatography (HPLC) is examined briefly.
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Comprehensive Screening, Confirmation, and Quantification of Organic Pesticides in Foods by GC–MS and LC–MSWith the globalization of trade, food production and distribution have become truly international businesses. When we dine out, the fish might come from Japan, the rice from Australia, the spices from China, and the strawberries from Mexico. We take it for granted that the food we eat is safe and free from contamination that could make us seriously ill.
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Chromatography Applications in Drug Discovery of Therapeutic ProteinsIn this month's installment of "Directions in Discovery," the authors discuss how, with the arrival of combinatorial libraries and high-throughput screening, pharmaceutical firms can develop new models of drug discovery that not only lessen the initial capital outlay involved in drug discovery, but also refine the discovery process.
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Method 6040D, Odors in Drinking Water, Using SPME on the Supelco SLB-5ms Capillary ColumnA method for trace odor components, isopropyl-methoxypyrazine (IPMP), isobutyl-methoxypyrazine (IBMP), methylisoborneol (MIB), and geosmin in drinking water involving the use of solid phase microextraction (SPME) and the SLB-5ms capillary column using gas chromatography/mass spectrometry (GC–MS).
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Ascentis® Express RP-Amide Expands the Selectivity of Fused-Core ™ Particle Technology HPLC ColumnsThe Fused-Core particle consists of a 1.7 micron solid core and a 0.5 micron porous shell yielding a 2.7 micron diameter. One of the benefits of the Fused-Core particle is the small diffusion path (0.5 microns) compared to conventional fully porous particles. The shorter diffusion path minimizes peak broadening. In fact, there have been many reports on the vast improvements in efficiency provided by Fused-Core particles versus conventional particles. These improvements provide sub-2 micron like performance at half of the backpressure allowing Ascentis Express columns to be used in conventional HPLC as well as UHPLC systems.
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Dynamic Extraction: A High-Speed, High-Capacity Purification Process That is Rapidly ScalableThe authors discuss a preparative process using the principles of countercurrent chromatography. This process is faster, capable of loadings from milligrams to hundreds of grams, and uses robust equipment.
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Chemometrical Experimental Design-Based Optimization Studies in Capillary Electrophoresis ApplicationsA synopsis of our work detailing the use of chemometric response surface methodology (RSM) in two capillary electrophoresis (CE) studies is described.
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Asymmetric Flow Field Flow Fractionation: A Powerful Method for Polymer CharacterizationRecent development of the instrumentation for asymmetric flow field flow fractionation (FFF) brings new possibilities for the characterization of synthetic and natural polymers with several advantages over traditionally used size exclusion chromatography (SEC). The main difference of asymmetric flow FFF compared to SEC is that the polymer separation takes place in an entirely empty channel, which eliminates undesirable SEC effects such as shearing degradation of polymers with ultra high molar mass, anchoring of branched macromolecules in SEC column packing, and enthalpic interactions of polymer molecules with a stationary phase.
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Fast Analysis of Third-Generation Cephalosporins in Human Plasma by SPE and HPLC MethodsA fast, selective, and reproducible high performance liquid chromatography (HPLC) method was developed and validated for the analyses of third-generation cephalosporin antibiotics, namely, ceftriaxone, cefixime, and cefdinir in human plasma. The analysis was carried out on a 150 mm Ã- 4.6 mm, 5.0-µm C18 column. The mobile phase used was 80:20 (v/v) 50 mmM phosphate buffer (pH 5.0)–methanol at a flow rate of 1.0 mL/min with 230-nm UV detection.
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Extraction and Detection of Antibiotics in the Rhizosphere MetabolomeRoot diseases caused by soilborne plant pathogens are responsible for billions of dollars of losses annually in food, fiber, ornamental, and biofuel crops. The use of pesticides often is not an option to control plant diseases because of economic factors or potential adverse effects on the environment or human health. For this reason, many Americans are now buying pesticide-free organic foods. Organic agriculture has few options for controlling pests and thus must make full use of natural microbial biological control agents in soils that suppress diseases.
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ICP MS Detection for HPLC Analyses of Pharmaceutical ProductsThe authors investigate applications for ICP-MS detection with reversed-phase HPLC.
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Challenges in Small-Molecule Quantitation by Mass SpectrometryDrug discovery scientists are continually striving to improve productivity and efficiency in their workflows. From early discovery to clinical development, existing workflow bottlenecks represent an opportunity to develop solutions to speed the process and improve productivity. The key requirements for quantitative analysis are precision, accuracy, and linear dynamic range. With any quantitative instrument, the hope is that it will be applicable to a vast range of coumpounds, ruggest, and fast. New mass spectrometry (MS) technologies are being developed that meet these criteria and permit high throughput while enabling its application to areas in which speed limitations previously curtailed its practicality. In particular, in the area of ADME profiling, new MS platforms are becoming available that increase the throughput by at least 25-fold, by combining the speed of matrix-assisted laser desorption ionization (MALDI) with the specificity of triple-quadrupole MS. This is bound to greatly accelerate the ADME..
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ICP MS Detection for HPLC Analyses of Pharmaceutical ProductsThe authors investigate applications for ICP-MS detection with reversed-phase HPLC.
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Robust Oligonucleotide Molecular Weight Confirmation via LC/MSOligonucleotides—therapeutic agents for difficult-to-treat diseases—rely on precise molecular weight confirmation to ensure quality during development. Experts from Agilent Technologies explore the challenges of liquid chromatography-mass spectrometry (LC/MS) analysis in oligonucleotide synthesis, as well as strategies for accurate deconvolution, method development, and optimal equipment selection.
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A New Perspective on the Challenges of Mass SpectrometryFor drug discovery workflows, the issue of metabolite detection and identification in in vivo systems is a critical challenge. The wide range of complex matrices (such as bile, plasma, urine, and fecal extracts), and the ion suppression effects of these biological fluids, can cause a severe decrease in the ability to detect metabolites. Greater instrument sensitivity is necessary to detect these compounds and, at the same time, helps to minimize sample preparation, simply diluting the negative effects of these complex matrices and avoiding the time- and labor-consuming sample cleanup or concentration steps that otherwise might be required.
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Rapid Determination of Azo Dyes from Textile Samples Using Dionex ASE and U3000 HPLC-UV Instruments with MSQ Plus DetectionAzo dyes are used widely in the manufacture of various consumer goods such as leather, textiles, plastics, paper, hair care products, and cosmetics. On September 11, 2003, the European Union enacted European Parliament Directive 2002/61/EC, prohibiting the manufacture and sale of consumer goods containing specified azo dyes (1). The azo dyes of concern are those that can be reduced to aromatic amines. There are 22 aromatic amines classified as carcinogenic or potentially carcinogenic to humans.
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Removal of Endogenous Matrix Components Using EVOLUTE® CX Mixed-Mode Cation Exchange Solid Phase ExtractionSample preparation is an essential technique to remove unwanted matrix components prior to LC–MS-MS analysis of drugs in biological fluids. Plasma matrix components whether endogenous (salts, proteins, and phospholipids) or exogenous (dosing vehicles, e.g. PEG 400), can interfere with compounds of interest leading to regions of ion suppression or enhancement. This can lead to inaccurate quantitation and have adverse effects on sensitivity. Mixed-mode SPE provides cleaner extracts as a result of rigorous interference wash steps, afforded by the dual retention mechanism of the sorbents.
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A New High-resolution Strong Cation-exchange 1 mm i.d. Column for the Separation of ProteinsThe new 1 mm i.d. ProSwift strong cation-exchange (SCX) column is a polymethacrylate-based monolithic column with sulfonate functionality.
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Reversed-Phase HPLC Column at Extreme High Temperature (150°C or Higher)In general, polymer-based columns have a broad pH range (pH 2 to 13), and some have high temperature tolerance (up to 150°C or higher). Considerably large selectivity changes can be obtained by varying analysis temperature and mobile phase pH. Having control on these two parameters over wide ranges can be especially useful in method development.
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A New High-resolution Strong Cation-exchange 1 mm i.d. Column for the Separation of ProteinsThe new 1 mm i.d. ProSwift strong cation-exchange (SCX) column is a polymethacrylate-based monolithic column with sulfonate functionality.
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Dosing Vehicle Removal in Discovery Phase Pharmacokinetic Studies Using High-Field Asymmetric Waveform Ion Mobility SpectrometryThis article describes the ability to increase the sensitivity for a target compound in the presence of high-level background impurities by removing the dosing vehicle using a high-field asymmetric waveform ion mobility spectrometry gas-phase separation before mass spectrometry analysis.
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High-Throughput Profiling of Long Chain Fatty Acids and Oxylipins by LC–MSLong chain fatty acids (LCFAs) function as a source of metabolic energy, substrates for membrane biogenesis, and storage of metabolic energy. Oxylipins, oxygenated derivatives of LCFAs, regulate the activity of many cellular processes. Existing methods for the analysis of LCFAs and oxylipins have limited compound coverage and sensitivity that, therefore, prevent their application in biological studies. In this work, we developed a high-throughput LC–MS method for analysis of 51 LCFAs and oxylipins. LCFAs and oxylipins were first extracted from biological samples via solid-phase extraction. The extracted molecules were analyzed by targeted comparative metabolomics. Saturated and monounsaturated LCFAs were analyzed in single ion reaction mode, while polyunsaturated LCFAs and oxylipins were analyzed in multiple reaction monitoring mode. Using this method, we successfully quantified 31 LCFAs and oxylipins from mouse livers.
