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12 Current white paper about the topic molecular weight

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Characterizing Biotherapeutics with HPLC

Smart Solutions for large Molecules

24-11-2010

As demonstrated here, there are a broad range of HPLC applications used in development, production, validation and release of protein therapeutics for human use. Some of the applications mentioned above are mandatory when submitting a new biopharmaceutical to approval at the regulatory agencies. The introduction of the first so-called biosimilars in Europe further increased the demand for highly efficient analysis methods. The continuous development of new stationary phases for the common modes of biochromatography, such as size exclusion, ion exchange and hydrophilic interaction chromatography support biochemists in increasing lab productivity and establishing high-throughput HPLC analysis not only for small molecules but also for large biopolymers...

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Analysis of water soluble polymers using linear size exclusion HPLC columns and a semi-micro SEC system

16-11-2010

One of the most widely used water-soluble polymers is Polyvinylpyrrolidone (PVP). For more than 70 years it is applied in a variety of applications in medicine, pharmacy, cosmetics and industrial production. PVP binds to polar molecules exceptionally well. It supports the solubility of tablets in water, makes the glue stick adhesive and plays an essential role in the production of membranes. In ceramic, paper and dye applications, it produces visual effects such as gloss and brilliancy. As a food additive, PVP is a stabilizer (E1201). A characteristic feature of a certain polymer is its molecular weight distribution curve, which is usually obtained by SEC Analysis...

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Field-Flow Fractionation - The Universal Separation Principle for Particle and Macromolecule Characterization

22-09-2010

High molecular weight polymers, bio molecules or particles in a range of a few nanometers up to several microns are more and more important in science and technology. Many applications are based on the specific properties of these materials. For this reason, an exact knowledge of the molar mass or particle sizes distribution is essential for later application as well as for optimization of the production processes or quality control. In addition the knowledge about the chain structure of macromolecules or biopolymers as well as about the shape of particles is often necessary. For this reason those samples, which often can be very complex systems, have to be separated according to parameters such as e.g. hydrodynamic volume or molecular weight. After the separation process the resulting narrow dispersed fractions are detected with different techniques....

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Absolute Molar Mass Characterisation

27-11-2009

Multi-angle light scattering coupled to SEC or other fractionation methods can provide an absolute means for measuring the molar mass, size and distribution of proteins, polymers and particles of all sorts. Wyatt Technology's MALS also enables the elucidation of additional data such as branching, conformation, and eluent behaviour. The same instrumentation also allows observation of molecular interactions in a real-time environment. As MALS is an absolute mass and size measuring technique it is insensitive to the separation mechanism and as such is ideal for both highly variable research applications as well as routine quality assurance of previously characterised samples...

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New Silicone Technologies for Skin Care

16-11-2009

In today's competitive skin care market, consumers look for a range of benefits, superior aesthetics and cost effectiveness. In response, formulators strive to create products that are multifunctional, easy to use and effective in small quantities. At the same time, the most successful products deliver benefits that stand out from those of the competition. Creams, lotions and color cosmetics must be easy to spread and comfortable to wear, without feeling tacky or greasy. Silicones have been popular ingredients in skin care products for more than fifty years. These versatile materials are known for their emolliency, wetting and spreading characteristics and ability to provide unique aesthetics. As technology continues to evolve, silicones increasingly offer multifunctional, high performance properties. This article reviews some of the newest silicone technologies available for the formulation of innovative skin care products...

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Asymmetric Flow Field Flow Fractionation (AF4) - A Powerful Method for Polymer Characterization

05-11-2009

The AF4-MALS combined technique can serve as a routine method for polymer analysis and characterization. AF4 provides separation efficiency entirely comparable with traditionally used and so far dominating SEC. In addition, it yields superior separation of branched polymers, polymers containing ultra high molar mass fractions up to at least 108 g/mol, and nanoparticles. This contribution outlines the theoretical background of the method and shows several examples of its use, e.g. separation of high molecular weight polymers and particles. While SEC will certainly continue to be the most frequently employed method of polymer analysis, for many samples the description of molecular structure is more detailed if both SEC and AF4 are used. The possibility to run both SEC and AF4 on the same experimental set-up makes the AF4 method a powerful and versatile tool for the characterization of a variety of synthetic and natural polymers and related materials....

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Bearing grease selection

03-09-2009

Rolling-element bearings are used for the precise guidance of moving parts. Frictional losses are extremely small because the bearings rest on rolling elements, enabling very heavy loads to be adsorbed. Rolling-element bearings may be lubricated with greases or oils depending on the point of use. Lubrication is necessary to prevent direct metallic contact between rolling elements and bearing rings, thereby preventing wear due to welding, friction, material fatigue or corrosion...

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Polyolefins: Determination of Molecular Weight and Branching Structure by GPC/SEC

16-06-2008

Polyethylene and Polypropylene are so-called Polyolefins. They are produced in large amounts every year. Depending on the process and catalyst used linear or branched polymers can be produced. In case of e. g. Polyethylene there are at least three polymer types: HDPE (High Density Polytheylene), LDPE (Low Density Polyethylene) and LLDPE (Linear Low Density Polytehylene). HDPE and LLDPE are made of linear or only slightly branched macromolecules with a high level of crystallinity. They form a dense structure in the final product. LDPE is made of highly branched molecules that form a final structure with low density due to a low degree of crystallinity....

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Measurement of Nano particles and Proteins

08-11-2006

Colloid emulsions in their native environment require particle size determination in high concentration since there are concerns about changes in sample morphology upon dilution eg break up of aggregates. For proteins and other samples with very low concentration and for weakly scattering samples high sensitivity is required. New technologies offer both....

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"Triple Detection" in Gel Permeation Chromatography

11-11-2005

Gel permeation chromatography (GPC) or also named size exclusion chromatography (SEC) is the most often used method for determining the molecular weight of natural and synthetic macromolecules. One specific strength of this method lies in the fact that by the separation process the whole molecular weight distribution is obtained. The molecular weight distribution contains much larger information for the characterization of polymer samples compared to a single value....

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