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Quick and Easy Membrane Characterization with GPC-SEC
June 1st 2008Size exclusion chromatography is a powerful tool for the characterization of molecules differing in size and molar mass. It is widely used and well known for the determination of molar mass distributions and molar mass averages. For membranes GPC-SEC is a useful characterization method as it can measure the membrane characteristic pore size distribution, average pore size and molecular cut-off significantly faster than other methods.
Aminoglycoside Antibiotics in Feed: Apramycin and Neomycin
June 1st 2008Aminoglycoside antibiotics are among those commonly used in animal feeds to manage intestinal microorganisms. The beneficial effects include improved growth and generally healthier animal populations. Use of antibiotics creates a demand for analytical procedures to verify concentrations in pre-mixes and feeds and in some instances for residue analysis in animal products.
Analysis of Deoxynivalenol in Beer
June 1st 2008Mycotoxins, toxic secondary metabolites of several fungal species, represent food safety issues of high concern. Deoxynivalenol, the most abundant trichothecene mycotoxin, can be found worldwide as a contaminant of wheat, barley, maize and other cereals (1,2). The transmission of deoxynivalenol from barley into beer has been reported in several studies (3,4). Therefore, its levels should be controlled.
Quantitative LC–MS Analysis of Pefluorochemicals
June 1st 2008This application note describes a fast and sensitive LC-MS method using a Hypersil GOLDâ„¢ column on a Thermo Scientific LC-MS system for the quantitative analysis of two widespread PFCs, perfluorooctanoic acid (PFOA) and perfluorooctansulfonate (PFOS).
Isolation and Purification of Polysaccharides
June 1st 2008In the last few decades, the novel functions of polysaccharides have provided a major impetus for increasing scientific attention. Among the most promising aspects are their immunomodulatory and antitumor effects, thickening agents and stabilizer effects.
Rapid and Rugged Determination of Glucosamine in Dietary Supplements Using HPAE-PAD
June 1st 2008Glucosamine (GlcN) is a major structural component in the biosynthesis of glycosaminoglycans, compounds involved in normal joint function. Use of GlcN as a dietary supplement in the management of osteoarthritis has attracted considerable attention; it is one of the five nonvitamin, nonmineral supplements most frequently used by US adults (1). The US FDA currently regulates dietary supplements to ensure that they are produced under cGMP (2).
Direct Determination of Cyanate in a Urea Solution and a Urea-Containing Protein Buffer
June 1st 2008Urea is commonly used in protein purification, including large-scale purification of recombinant proteins for commercial purposes, and in recombinant protein manufacturing to denature and solubilize proteins (1). In aqueous solutions, urea degrades to cyanate and ammonium, with the maximum degradation rate occurring at neutral pHs commonly used in biological buffers (2). Cyanate is problematic in urea solutions because it carbamylates proteins, which causes unwanted modifications that can alter the protein's stability, function, and efficiency. Therefore, an accurate, sensitive method for determining cyanate in urea-containing buffers is required.
Metabolic Profiling of Peanut Plant Material by LC–TOFMS
June 1st 2008There 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.
Increasing LC–MS-MS Sensitivity with Luna® HILIC
June 1st 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:
Method 6040D, Odors in Drinking Water, Using SPME on the Supelco SLB-5ms Capillary Column
June 1st 2008A 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).
Branching in High Molar Mass Synthetic Amyloses
June 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.
Analysis of Melamine and Cyanuric Acid in Food Matrices by LC–MS-MS
June 1st 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.
Determination of Urea and Allantoin in Cosmetics
June 1st 2008Urea and allantoin are added to cosmetic products for skin protection and regeneration, especially for the treatment of dry skin, and analyzed for QC purposes. As polar compounds, they are not ideal for reversed-phase HPLC separations. Neutral hydrophilic compounds like urea and allantoin are best analyzed by hydrophilic interaction chromatography (HILIC). Traditional HILIC columns use silica modified with a hydrophilic group such as diol or cyano. Analytes are adsorbed and subsequently eluted with mobile phases containing high percentages of organic solvent (>75%).
Automated Sample Cleanup of Olive Oil
June 1st 2008Gel permeation chromatography (GPC) has been used as an effective cleanup procedure for removing high molecular weight interfering molecules such as lipids, pigments, proteins, and polymers before GC or HPLC analysis. The GPC cleanup method has been extensively documented (1–3) and is also recommended in US EPA SW-846 Method 3640A. To demonstrate the efficacy of this method to extract polar and nonpolar substances by using the KNAUER Smartline GPC Cleanup Unit 6500, olive oil samples were investigated by spiking these with different types of organic pollutants, including PAHs, phthalates, phenols, and triazine.
The Pharma QC Column: OROSIL C18
June 1st 2008The QC for the pharmaceutical industry is based on methods developed on a variety of columns. At Orochem, we have attempted to address method development utilizing unique chemistries such as the OROSIL C18 to analyze a wide range of acidic, basic, and neutral compounds. Data is presented on a few representative compounds and unique separation criteria with their associated chromatograms.
Fast Enantioselective Chromatography with 3-µm Particles
June 1st 2008The continuing and growing trend toward high-speed analysis in all fields of chromatography is also reflected in enantiomer separations. A variety of new 3-μm columns has been designed to meet this need. Applications of CHIRALCEL® OD-3 and CHIRALPAK® AD-3 in some enantiomer separations demonstrate the benefits of transitioning to such media.
High Sensitivity Analysis of 12 Synthetic Food Colorants by U-HPLC with Diode Array Detection
June 1st 2008The natural colors of the food we eat add greatly to the enjoyment of life. Consequently, the art and science of recreating food's natural colors through the use of synthetic colorants is an important success factor in the food industry.
Direct Plasma Analysis of Drug Compounds Using Onyx Monolithic Columns
May 10th 2008The tandem use of liquid chromatography and mass spectrometry has become the principal mode of pharmaceutical analysis, especially for high throughput analysis employed in DMPK studies. Rapid analytical data generation is pivotal during these early stages of drug discovery.
Overcoming Compound Volatility with Sub-ambient ELSD
May 10th 2008Polymer Laboratories, now a part of Varian, Inc. has published an application note on Overcoming Compound Volatility with Sub-ambient ELSD. Sub-ambient evaporative light scattering detection is valuable in the analysis of semi-volatile compounds. The Varian 385-LC has been specifically developed to operate at sub-ambient evaporation temperatures, using a Peltier cooled evaporation tube. This application note shows that sub-ambient ELSD at 20 ?C, as delivered by the new Varian 385-LC, increases the accuracy of measurement by minimizing compound volatility effects.