Static Light Scattering
Static light scattering (SLS) is a technique to measure absolute molecular weight using the relationship between the intensity of light scattered by a molecule and its molecular weight and size, as described by the Rayleigh theory.
Dynamic Light Scattering, Electrophoretic light scattering, Meet the Experts, Static Light Scattering, Zeta potential, Zetasizer »
Recently, I hosted a webinar which discussed what surface zeta potential is and how it can be measured. The webinar attracted huge interest and it was a pleasure to see so many people attending and asking some excellent questions. In fact, there were so many questions asked, that we ran out of time at the end of the webinar and had to answer many of them via e-mail. Some of these are listed below.
The webinar discussed the zeta potential of solid, planar surfaces (rather than colloidal dispersions or molecular solutions) …
Binding affinity and Kd, Differential Scanning Calorimetry, Dynamic Light Scattering, Français, Gel permeation chromatography, Image Analysis, Isothermal Titration Calorimetry, Laser Diffraction, Meet the Experts, Molecular size, Nanoparticle Tracking Analysis, Particle concentration, Particle size, Rheological and Viscosity, Rheometry - Rotational, Size Exclusion Chromatography, Static Light Scattering, Zeta potential »
Afin de vous apporter un support concret pour utiliser votre système de façon optimale, finaliser vos bonnes pratiques de laboratoire et répondre à vos besoins spécifiques, Malvern organise des formations sur site ou en sessions dans nos 3 agences françaises (Orsay, Lyon et Toulouse).
Voici les dates de toutes les sessions programmées pour 2017 :
CARACTERISATION DES PARTICULES PAR DIFFRACTION LASER
Objectifs : Perfectionner les méthodes de caractérisation des particules en voie sèche et liquide, définir les bonnes pratiques de laboratoire et s’adapter aux besoins spécifiques de chaque installation. Comprendre le principe physique …
Dynamic Light Scattering, Français, Laser Diffraction, Malvern Events, Meet the Experts, Nanosight, Particle size, Static Light Scattering, Zetasizer »
Les 20èmes rencontres organisées à Rennes auront lieu du 28 au 30 novembre avec la collaboration l’Institut des Sciences Chimiques de Rennes et la plateforme ScanMat. La directrice de cette plateforme, Maryline Guilloux-Viry, nous fera l’honneur d’accueillir les participants et de présenter les moyens et compétences disponibles au sein de la fédération des 5 plateformes constituant ScanMat (Microscopies électroniques, Analyses structurales et élémentaire, Synthèse et mise en forme, Spectroscopies et Microspectroscopies optiques).
Les nanoparticules seront au cœur de ces rencontres avec une évocation des nouvelles réglementations de REACH qui seront en vigueur …
Corporate, Malvern Events, Meet the Experts, Raman spectroscopy, Spraytec, Static Light Scattering »
You are seriously considering ordering a Zetasizer. An excellent choice! A typical email we often receive at this point is:
“What are the site requirements for the system?”
The Malvern Zetasizer is a compact benchtop measurement system which requires little space on a standard laboratory lab bench. It also requires connection to a computer (either standard PC or a laptop). All requirements are listed in the manual, which is automatically placed on your computer in PDF format, along with the software and available under
Start –> All Programs –> Malvern Instruments –> Zetasizer Software –> Documentation …
You may have noticed that the Zetasizer instrument range is available in two different optical configurations: the ‘traditional’ 90 degree setup and the ‘NIBS’ 173 degree setup.
An obvious question for a dynamic light scattering (DLS) user is:
“Will I get the same results from both systems?”
This can be a tricky concept to understand, so we’ll do our best to explain here. First though, we should not that, aside from its larger scattering angle, the NIBS (Non-Invasive Back Scatter) system also has a much larger concentration range than the 90 degree system, meaning the NIBS system …
Looking over an old powerpoint file from Viscotek, an interesting slide on a unique application stood out. Investigating samples of the 20S Proteasome by light scattering in conjunction with refractive index RI was able to clearly determine whether a particular sample contained ‘filled or empty’ proteasomes.
In that case, both the empty and the loaded proteasome showed an RI peak at the same elution volume. Thus with conventional calibration, one would have had to conclude that these samples had the same molecular weight. However light scattering revealed that the filled proteasome …
Dynamic Light Scattering, Meet the Experts, Molecular weight, Particle size, Static Light Scattering, Zetasizer »
In dynamic light scattering (DLS) we are usually mostly concerned with the level of intensity fluctuations – nevertheless we do need to see a good signal before we can analyze it. The signal strength is the scattering intensity and it is measured in photons per second, or most often as in the Zetasizer in kilo counts per second, kcps for short. The actual average number of photons per second arriving at the detector is also called the mean count rate, the actual count rate, or just the scattering intensity.
What is the mean count rate?
If the detector …
Gel permeation chromatography, Molecular weight, Size Exclusion Chromatography, Static Light Scattering, Viscotek »
How to get the latest OmniSEC GPC software
One of the new developments at the Malvern exhibit at Pittcon is the OMNISEC system. If you are in New Orleans, come by our booth 3545 and take a look. We have already talked with quite a few existing users of our TDA and 270 systems. Did you know that the latest sofware version for our GPC / SEC systems is available for download from our website?
Where can I find and download the latest version of the OnniSEC software?
How to update your OmniSEC software:
Quick answer: OmniSEC software version 5.10
Dynamic Light Scattering, Molecular size, Molecular weight, Size Exclusion Chromatography, Static Light Scattering, Tech Talk, Viscotek, Zetasizer »
The term polydispersity (or more recently dispersity without the poly, as per IUPAC recommendation) is used to describe the degree of “non-uniformity” of a distribution. In the field of molecular/nanoparticular characterization there are in principle two different definitions of polydispersity, depending on the underlying property of interest.
In Gel Permeation Chromatography (GPC) and Size Exclusion Chromatography (SEC) we are interested in the molecular weight of the sample. The distribution obtained from GPC/SEC is typically a molecular weight distribution describing how much material there is present of the various molecular weight “slices.” The …
Last week we offered a webex presentation titled “Speed your way through protein formulation screening by automating your measurements: A2/B22 with the Zetasizer APS”
The presentation had a focus on protein formulation, where often the objective is to assess protein stability as a function of various parameters. Here, light scattering can be used as a tool to assist in screening conditions:
Monitor: Aggregation temperature, Dynamic Light Scattering (DLS) vs temperature
Predict: Interaction parameter, DLS vs concentration
Predict: Second Virial Coefficient, Static Light Scattering (SLS) vs concentration
While the Zetasizer APS has previously been used for dynamic …Read the full story »
When is Single Angle Light Scattering (LALS/RALS) the right detection technique to use, and when do you need Multi Angle Light Scattering (MALS)?
Size Exclusion Chromatography (SEC) is a well-established tool for the measurement of the molecular weight and purity of proteins and polymers. It is based on the separation of molecules based on their hydrodynamic volume and size – not their molecular weight.
In its simplest form, sometimes called Conventional Calibration, SEC uses an RI or UV detector, and the elution volume is calibrated against known standards. Sounds pretty easy, however, the …
When light scattering (low-angle LALS, right-angle RALS, or multi-angle MALS) is used for molecular weight detection in chromatography, the eluting mobile phase should be free of any material or particulates other than the sample. Even the best chromatography columns can shed some particulates from their packing material and this shedding often scatters a significant amount of light and can create noise in the light scattering detector signals adversely affecting results. This noise isn’t present in other detectors because they are not sensitive to particulates in the same way.
To mitigate against …
Dynamic Light Scattering, Meet the Experts, Molecular size, Molecular weight, Static Light Scattering »
ATA Scientific Pty Ltd, distributor of Malvern Instruments products throughout Australia, will be an active exhibitor at the upcoming Lorne Proteins Conference (9th – 13th February). An informative 1 hour workshop, entitled “The illumination of protein structure using light scattering” will be given by me, Michael Caves, from 1.30 – 2.30 pm on the 10th, and a poster on the same subject will be presented. Following this, ATA host a seminar series on the use of light scattering technologies to probe the structure of polymers and proteins from 13th – 18th February. I will …Read the full story »
Corporate, Gel permeation chromatography, Laser Diffraction, Size Exclusion Chromatography, Static Light Scattering »
Fragment antigen binding (Fab) proteins are fragments of monoclonal antibodies (mAb) which can be obtained by enzymatically digesting mAb with papain. About a third in molecular weight, Fabs have been used to treat macular degeneration, cardiovascular diseases, and snake bites, where the faster tissue penetration is an advantage after the administration of anti-venom.
In scientific research, Fabs have been of interest in structural biology to for example help understand antibody-antigen interactions, or obtain molecular structures through Fab-mediated protein crystallization.
This is an example of an Antibody fragment. The run conditions and some …
Corporate, Gel permeation chromatography, Molecular weight, Size Exclusion Chromatography, Static Light Scattering, Tech Talk, Viscotek »
A list of historic Viscotek models
When Viscotek became part of Malvern in 2008 it had already been a market leader in Gel Permeation Chromatography GPC, Flow Injection Polymer Analysis FIPA as well as dilute solution viscometry DSV for over 20 years. Founded in 1984 by Dr. Max Haney who invented the four capillary differential viscometer detector, the company had continuously innovated a portfolio of state-of-the-art instrumentation suitable for addressing unique molecular characterization challenges. Due to their solid build quality we still encounter some of the older generation Viscotek models today – …
Refractive index increment dn/dc values when you need them?
In light scattering a crucial parameter which appears together with the Rayleigh Ratio RΘ is the refractive index increment, also known as “dn/dc”. Typically Kc/RΘ is plotted versus concentration to extrapolate to zero concentration and obtain the molecular weight in a batch SLS (static light scattering) measurement. The factor K consists of
where n is the refractive index of the solvent, λ the wavelength of the laser, and NA is Avogadro’s number. The refractive index increment applies to the sample under a specific condition. For example, …Read the full story »
Malvern Events, Molecular size, Molecular structure, Molecular weight, Size Exclusion Chromatography, Static Light Scattering, Tech Talk, Viscotek, Zetasizer »
Earlier this month Mark Pothecary and Paul Clarke (Product Manager and Product Group Manager respectively for Nanoparticle and Molecular Characterization) presented a webinar on a variety of analytical technologies suitable and of interest to biopharmaceutical industry. The recorded event touched on well-established characterization techniques, including light scattering (LALS/RALS/DLS) and size exclusion chromatography (GPC/SEC) and illustrated the benefits of combining complementary information for protein scientists.
This webinar was very well attended, and can still be viewed on the C&EN website here. However, due to the significant number of attendees, not all questions could be answered ‘live’ – so we thought it might be useful …
Dynamic Light Scattering, Malvern Events, Size Exclusion Chromatography, Static Light Scattering »
Now firmly back in the UK, this is my final post about last week’s Pittcon activities. Not only was this one of the first occasions where people had the opportunity to learn about the Morphologi G3-ID, Pittcon was also a launch pad for the new Zetasizer µV with OmniFACE and OmniSEC, a new SEC-LS (size exclusion chromatography – light scattering) detector package dedicated to protein analysis.
In this short video, shot on Malvern’s Pittcon booth, Jason Sanchez, Product Manager, GPC/SEC Technologies takes you through the system
And for even more detail visit …