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Particle sizing with static laser scattering
When determining particle sizes a wide variety of techniques are used in which sieving may be the most popular. Sieving is a relatively simple technique, despite the fact that of course different instrumental approaches can be used. The main advantages of sieving are the low price of the instrumentation and the fact that different fractions of the original sample can be prepared for further use. On the other hand, sieving is very time consuming and yields results only for a very limited number of particle sizes. Results from sieving typically vary due to several factors: the method of moving the sieve, the period of operation, the number of particles on the sieve and some physical properties such as shape or stickiness of the sample. In addition, the actual size of the mesh gaps of the sieves can have large variations from the nominal size...
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Characterization of micelles and liposomes using the Eclipse 3+ AF4 separation system coupled to a DAWN HELEOS II MALS detector
Micelles and liposomes can serve as vehicles used to solubilize and carry bioactive compounds to their site of action, thus increasing their bioavailability. First experience has been made using vitamins and enzymes as functional food additives. Moreover, micelles could be useful to deliver drugs to a defined site of action, thus reducing frequently occurring side effects of systemic drug administration. Micelles are true nano-materials with a size range of 10 to 30 nm in diameter. Ideally, they should have a narrow size distribution. Furthermore, they have to be stable and should release their active compound only in the target region. Characterization of the micelle suspensions is vital to guarantee these properties and has to cover several aspects. One important point is size distribution, which has to be determined with high resolution...
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Automated Dynamic Light Scattering
DLS analysis is a widely applied, non-invasive method for measuring the effective size of molecules in solution. This technique yields valuable information for the characterization of molecules and particles. It facilitates formerly laborious and time consuming measurements, e.g. screening for aggregates or determining optimal crystallization conditions for proteins. The Wyatt Plate Reader is the instrument of choice for any application where molecular size, stability and aggregation are of interest. It reads industry standard microplates with up to 1536 samples automatically and temperature-controlled, if desired. The applications of the technique are wide ranging and include many of the fastest growing areas of research - proteins, biomaterials, liposomes and micelles as well as the established uses for particle sizing and aggregation detection. Conscious of the numerous characterization challenges in the area of drug delivery systems and therapeutic antibodies...
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Asymmetric Flow Field Flow Fractionation (AF4) - A Powerful Method for Polymer Characterization
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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Particle Analysis: Quality Control of Catalysts with Digital Image Processing
Catalysts are widely used as an important auxiliary material in the chemical and petrochemical industry. They are able to accelerate chemical reactions by lowering the activation energy, i.e. they change reaction kinetics. Thus, using catalysts in industrial processes has the advantage of higher productivity combined with less energy consumption....
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