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Branching in High Molar Mass Synthetic Amyloses
September 1st 2008Amylose is an occasionally-branched biopolymer and, together with amylopectin, the hyper-branched component, a constituent of starch. Determination of branching in amylopectin on the basis of amyloses may be performed with the help of synthetic amyloses. Synthetic amyloses from enzymatic (phosphorolytic) reaction were checked for their linearity.
Increasing LC–MS–MS Sensitivity with Luna HILIC
July 2nd 2008The 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
A Highly Selective Method for the Analysis of Drospirenone in Human Plasma
July 2nd 2008Several 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.
"Polymer Status" of Synthetic Oil Under REACH Context
July 2nd 2008Under the registration, evaluation and authorization of chemicals (REACH) Regulations (EG) no. 1907/2006 the producer, manufacturer or importer of chemical substances/formulations have to register their products (more than 1 ton/year) at the chemical agency.
Characterization of PEGylated Lysozyme by Size Exclusion and Ion Exchange Chromatography
July 2nd 2008PEGylation, the process by which polyethylene glycol (PEG) chains are attached to protein and peptide drugs is a common practice in the development of biopharmaceuticals to prolong serum half-life and improve pharmacokinetics of a drug. There is increasing demand for chromatographic methods to separate the modified isoforms from the native protein. This application note describes the use of size exclusion and ion exchange chromatography for the characterization of PEGylated lysozyme.
Analysis of Melamine and Cyanuric Acid in Food Matrices by LC–MS–MS
July 2nd 2008In 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.
Quantitative LC–MS Analysis of Perfluorochemicals
July 2nd 2008This 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).
LCxLC: Comprehensive Two-Dimensional Liquid Chromatography
July 1st 2008Guest 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.
Flexible Fused Silica Capillary: A Review of Internal Surface Chemistry
June 1st 2008Synthetic fused silica capillary tubing has proven to be a vital component in many separation science techniques. Recently, it has expanded to serve an array of scientific markets. In most cases, an understanding of the internal surface chemistry is of fundamental importance.
On-site Sample Preparation Using MEPS for Waste Water Analysis
June 1st 2008MEPS uses a barrel insert and needle (BIN) device to reduce Solid-Phase Extraction (SPE) to a micro-scale suitable for small volume samples and for the online adaptation of conventional SPE techniques. Because the SPE cartridge (BIN) is incorporated into the needle assembly of a gas-tight syringe, MEPS is also a simple field-portable SPE device that may be operated manually without need for sampling pumps or, alternatively, may be incorporated into robotic samplers. MEPS devices are of glass and stainless steel construction allowing them to be fully immersed for sampling at depth or, alternatively, used at needle depth to avoid perturbing the stream from which the sample was drawn. An extension pole allowed MEPS to be used to sample back along pipes or down inspection vents. When sampling from drainage pits and open sumps, there was minimal requirement to remove grates to gain access. An extension pole also allowed sampling from outflows that were offensive and could be readily adapted for safe sampling of..
Extraction of Basic Drugs from Plasma Using EVOLUTE CX 96-Well Plates and Columns
June 1st 2008his application note describes the extraction of a variety of basic drugs from plasma using EVOLUTE CX mixed-mode resin-based SPE. The analyte suite includes basic drugs with wide ranging pKa and logP values.
Rapid Analysis of Flavors and Fragrances Using High-Efficiency GC Columns
June 1st 2008There are many misconceptions about what it means to perform fast gas chromatography (GC) and what the term fast GC implies. Fast GC is often associated with the use of hydrogen as a carrier gas and, although this is certainly a good approach, it is not always necessary to shorten the analysis time. A second misconception is that changing column dimension results in time-consuming method development. Using high-efficiency GC columns can greatly reduce the analysis time and when coupled with the method translation software, the time spent on method development can be greatly minimized.
SELS — Solvent Enhanced Light Scattering
June 1st 2008Viscotek has been a strong advocate of good chromatography as a prerequisite for GPC (Gel Permeation Chromatography) data accuracy. Our recent work in application development has been driven by extremely difficult samples from industrial, biopharmaceutical, and academic sources. These samples present challenges ranging from sample solubility, column adsorption as well as detection issues. This report will attempt to highlight a new approach that could be very helpful in certain advanced GPC applications.
Determination of Organic Compounds in Drinking Water Using Atlantic SPE Disks for EPA Method 525.2
June 1st 2008EPA Method 525.2 describes the procedure to determine low ppb levels of semi-volatile organic material in drinking water using solid phase extraction (SPE) or liquid-solid extraction (LSE) techniques. The City of Fort Worth, Water Department implemented an automated SPE process for the analysis of semi-volatiles by EPA Method 525.2, using the Atlantic "Certified for Automation" SPE Disk for EPA Method 525.2. Ethyl acetate, methanol, and water were used to condition the Atlantic disk prior to the extraction step. The extraction solvents used were a 1:1 mixture of methylene chloride and ethyle acetate. Extracts were then analyzed by GC–MS using a splitless injection technique.
Analysis of Hydrophilic Molecules in Biological Fluid with Novel Mixed-Mode Column
June 1st 2008In pharmaceutical development, it is important to analyze small molecules or their metabolites in biological fluids. For this purpose, the analytical methods such as sample pretreatment, 2D-LC and LC–MS have been developed. However there are still problems of resolution and protein adsorption. As a result, satisfying analytical results have not always been achieved.
Automated Extraction Technique for Improved Recovery of Phenols
June 1st 2008Dionex has developed a new standard for flow-through solvent extraction which allows accelerated solvent extraction (ASE®) of matrices that have undergone acid or alkaline pretreatment or digestion. The new ASE 150 and ASE 350 systems use extraction cells and post-cell solvent pathways constructed of Dionium™ material. This pH-hardened substance resists corrosion under acidic or alkaline conditions used in standard pretreatments, widening the scope of ASE applications and significantly expanding its capabilities.
A Highly Selective Method for the Analysis of Drospirenone in Human Plasma
June 1st 2008Several 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.
Using pH-LC to Control Selectivity of Acidic and Basic Compounds on Gemini-NX
June 1st 2008The use of mobile phase pH to control analyte ionization states (pH-LCâ„¢) in reversed phase HPLC separations is a highly effective way to change selectivity. The ionized species of an analyte is shown to have higher polarity (less hydrophobicity) than the neutral species, which results in a loss of expected retention for that analyte. This can be attributed to less interaction with the hydrophobic stationary phase and greater affinity with the aqueous portion of the mobile phase. Ionized species also participate in ionic interactions with exposed and activated silanols, which impact peak shape and reproducibility.
Techniques for Reducing Purge-and-Trap Cycle Times in VOC Analysis
June 1st 2008The purge-and-trap (P&T) technique for analysis of volatile organic compounds (VOCs) was pioneered in the 1970s at the United States Environmental Protection Agency (USEPA) research laboratory in Cincinnati. Many of the operational parameters developed during this time period are still included in USEPA methods. While these parameters still produce good analytical results, they do not take advantage of advances in instrumentation that enable analysis of emerging contaminants such as fuel oxygenates, and increased sample throughput.
HPLC Analysis and Preparative Scale Purification of Synthetic Bradykinin
June 1st 2008Bradykinin, a 9 amino acid peptide, is a physiologically and pharmacologically active peptide of the kinin group of proteins, which is used in the development of antagonists and therapies for hereditary angioedema. In this application, 50 mg of crude bradykinin, synthesised on a StratoSpheresâ„¢ PL-Rink resin, is purified using an HPLC method that can be scaled from the laboratory through to full production.
The Use of Accurate Mass and MS-MS for the Analysis of PPCPs in Water
June 1st 2008The 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.