TESTA Analytical Solutions is purely focused on polymer characterisation and particle sizing, offering the most advanced solutions and equipment for these tasks. For 30 years we have collected our experience in the field, and we are happy and proud to share our knowledge with researchers worldwide assisting in the most demanding applications.
TESTA Analytical Solutions is one of the few manufacturers focused on GPC/SEC instrumentation. For Particle Sizing, SLS ad Zeta Potential we have partnered with Brookhaven Instruments Corp. , we distribute and service their full portfolio in a number of different countries of northern and central Europe.
GPC/SEC is without a doubt the most flexible technology available today for a compleate characterisation of polymers.
It can be easily adapted to any application by optimizing separation and selecting the detection methods.
Static light scattering is a technique in physical chemistry that measures the intensity of the scattered light to obtain the average molecular weight Mw of a macromolecule in solution. Measurement of the scattering intensity at many angles allows calculation of the root mean square radius Rg. It also allows determination of the second virial coefficient A2.
Size determination of Nanoparticles is nowadays unthinkable without DLS. A solid method for many applications.
Zeta Potential is one of the major parameters of interest when stability of suspensions is investigated.
TESTA Analytical Solutions is fully focused on Polymer Characterization and Particle Sizing Technologies, offering the most advanced and refined equipment for the most challenging research, development and QC Tasks. TESTA Analytical Solution´s experts are known for their ability to help users solve the most intricate problems and applications, worldwide.
Our know-how is the fundament of our success.
and the most advanced technologies in Light Scattering (DL/SLS), Viscometry and GPC/SEC Chromatography
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TESTA Analytical Solutions e.K.
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Introduction
Testa Analytical Solutions e.K. has introduced a Surface Zeta Potential option for its NanoBrook range of zeta potential analysers.
Adding the new surface zeta potential option to a Nanobrook analyser allows you to measure the electrical charge on materials like coated glass, plastic, tape, or other flexible surfaces. The system uses known probe particles and purpose-designed electrode to calculate surface zeta potential.
NanoBrook Omni
Brookhaven's NanoBrook Omni instrument combines the best technology from our particle/protein sizer and zeta potential analyzer in to one powerful and accurate solution for sizing and zeta potential analysis. Measure samples in nearly every possible suspension environment from high salts such as PBS and sea water to organic solvents and of course aqueous solutions. Particle and protein sizing, with the highest sensitivity, utilizing three measurement angles for truly unbiased measurement results. The NanoBrook Omni utilizes a backscattering angle as well as 90° and 15°.
NanoBrook 90Plus ZETA
Brookhaven's NanoBrook 90Plus Zeta instrument combines our NanoBrook 90Plus and NanoBrook ZetaPlus instruments into one versatile package for routine sizing and zeta potential analysis. It employs Dynamic Light Scattering (DLS) for particles/molecules size and Electrophoretic Light Scattering (ELS) for particles/molecules surface charge evaluation. This package not only allows rapid measurements of the effective size and zeta potential of samples, but also provides further information on multimode distribution in size and surface charge in polydisperse samples. Based on the proven technologies of Brookhaven, the NanoBrook 90Plus Zeta guarantees excellent mobility measurement performance in aqueous suspensions and low salt environments
NanoBrook 90Plus PALS
Brookhaven's NanoBrook 90Plus PALS instrument combines our NanoBrook 90Plus and NanoBrook ZetaPALS instruments in to one powerful package for sizing and zeta potential analysis. With over a decade of proven records in diverse applications, Brookhaven's pioneer Phase Analysis Light Scattering (PALS) technology remains a step ahead of the competition. This package delivers unparalleled zeta potential (surface charge) measurement sensitivity and accuracy. It also provides unique real-time (in-situ) monitoring capability for electrophoretic response of particles/molecules under an electric field, a valuable tool ONLY from Brookhaven for delicate biological entities like proteins and exosomes. It has been successfully utilized in nearly every possible suspension environment from high salts such as PBS and sea water to organic solvents and of course aqueous solutions
NanoBrook ZetaPALS
For measurements of very low mobilities, the NanoBrook ZetaPALS is the answer. The only answer! With concepts developed at Bristol University and Brookhaven Instruments, the NanoBrook ZetaPALS determines zeta potential using Phase Analysis Light Scattering: A technique that is up to 1,000 times more sensitive than traditional light scattering methods based on the shifted frequency spectrum. Electrostatic repulsion of colloidal particles is often the key to understanding the stability of any dispersion. A simple, easy measurement of the electrophoretic mobility "even in nonpolar liquids" yields valuable information. Measurements made in water and other polar liquids are easy and fast with the NanoBrook ZetaPlus. Such measurements cover the range of typically ± (6 to 100) mV, corresponding to mobilities of ± 0.5-8x10-8 m 2 /V·s. The NanoBrook ZetaPALS covers this full range, of course, and extends it by a factor of 1000 in sensitivity!
NanoBrook ZetaPlus
The NanoBrook ZetaPlus is the simplest and most accurate particle electrophoresis system available. This revolutionary instrument has been designed to eliminate the short coming inherent in other zeta potential instruments. The ZetaPlus software is simple and intuitive to operate but yet offers flexibility and a full range of means for those that whish to tune their experiments to specific circumstances. The unique cell configuration eliminates the electroosmotic effect: No stationary levels, no alignment, and no calibration are required; as evidenced by the excellent agreement with NIST1980, a standard reference material. The NanoBrook ZetaPlus uses low cost, disposable sample cells. There is no assembly or maintenance required: Cross contamination is eliminated. Glass and quartz cells are available optionally. The same basic cell design is used with the NanoBrook 90Plus Zeta, ZetaPALS, 90Plus PALS, and Omni
BI-ZTU Autotitrator
The BI-ZTU, autotitrator option for the NanoBrook zeta potential analyzers is ideal for automatic determination of the isoelectric point, the IEP, of colloidal materials. Four pumps provide unparalled flexibility for optimizing reagent use. The dramatic savings of reduced labor costs will also encourage larger scale studies that will produce more valuable results. In addition, the BI-ZTU can be used to evaluate the effect of salt concentration on zeta potential. Also, the surfactant costs can be minimized. Use the BI-ZTU to find the minimum concentration at which the zeta potential does not significantly change.
Surface Zeta Potential Electrode
The Surface Zeta Potential feature allows the user to measure the electrical charge on materials like coated glass, plastic, tape, or other flexible surfaces. A series of measurements are taken on probe particles at different distances from a surface and the Surface Zeta Potential is calculated as shown above.
Particle Solution software
Designed to operate with NanoBrook series particle characterisation instruments, Particle Solutions software suite integrates characterisation of 5 different particle measurement technologies - DLS, SLS, Phase Analysis Light Scattering (PALS), micro-Rheology and Molecular Weight Determination in one package. The new version of this popular software suite for NanoBrook series particle characterisation instruments includes a host of useful new features. New features include Laboratory Information Management System support, Surface Zeta Potential measurement capability, Multimodal Size Distribution refinement, Health Mode post-measurement analysis, and Statistical Process Control. Safeguarding the investment of existing users - measurements made with earlier versions of the software can be imported into Particle Solutions, and then analyzed with the same powerful tools.
Note: Particle Solutions is only usable with Brookhaven Instruments light scattering systems.
Within a GPC/SEC Chromatography system, a viscometer allows use of a universal calibration. Molecular weights obtained with this method are therefore independent of the polymer standards used to build the calibration and can be considered to be close to absolute values. Also, a viscometer will allow determination of further molecular parameters giving insight about the physical structure of the investigated polymer and even opening the gate to determination of branching parameters. All viscometers for GPC/SEC currently on the market, including the AYE Viscometer, base their principle on the measurement of the differential pressure across a capillary network. TESTA has been able to dramatically reduce the noise level and increase sensitivity by more than an order of magnitude compared to any viscometer available. This allows usage at much lower flow rates than it has been possible. Detection of lower molecular weight and at lower concentration are now also possible. Semi-micro applications are currently easily reached.
Refractive Index - Viscometer GPC/SEC detector combo
The AYE Combo Refractometer /Viscometer sets a new standard for the detection of intrinsic viscosity of highly diluted samples. The Refractometer is integral part of the viscometer, therefore both concentration and viscosity are measured at exactly the same time on the very same sample segment. The AYE Combo allows a much more accurate determination of molecular parameters and is particular suited for those application focused on the structure and branching of the investigated polymer.
ParSEC advanced GPC/SEC software
ParSEC is a powerful new suite of software for multi detector, macromolecular characterization and represents the most significant development in GPC/SEC analysis. ParSEC is compatible with ALL GPC/SEC systems and detectors. Many attractive and practical features have been written into the new software for the benefit of chromatographers, including "function specific" views, ensuring the uncluttered display of information relevant to the task at hand, customizable display and annotation options for all graph types, plus a Database approach for practical storage and archiving of data and results associated with any application.
ReadyCal polymer standards
GPC/SEC Chromatography is impossible without Polymer Standards. For QC Applications which mostly uses a single concentration detector, Polymer Standards are required for Calibration of the Columns which then allows calculation of Molecular Weights. More complex GPC/SEC Systems with Viscometers and MALS, require Polymer Standards for the determination of Instrument Constants and for System Validation. 
These are the facts which make GPC/SEC without Polymer Standards impossible. A ReadyCal™ Kit combines highest quality standards with easy and fast handling, reducing errors in sample preparation practically to zero. Three sets each of four different pre-mixed standards in 1.5 mL screw cap Vials build the strong backbone of a reliable calibration curve. Just add the desired amount of solvent, shake according to instruction and inject. Column calibration cannot be easier.
NanoBrook Omni
Brookhaven's NanoBrook Omni instrument combines the best technology from our particle/protein sizer and zeta potential analyzer in to one powerful and accurate solution for sizing and zeta potential analysis. Measure samples in nearly every possible suspension environment from high salts such as PBS and sea water to organic solvents and of course aqueous solutions. Particle and protein sizing, with the highest sensitivity, utilizing three measurement angles for truly unbiased measurement results. The NanoBrook Omni utilizes a backscattering angle as well as 90° and 15°.
NanoBrook 173Plus
Brookhaven's’ NanoBrook 173Plus instrument is the go-to-solution for characterization of proteins, antibodies, nanoparticles, macromolecular assemblies and other molecules/particles of small sizes. The NanoBrook 173Plus uses backscattering detection for the highest sensitivity and accuracy optimized for molecules and particles less than a few tens of nanometers. Detection at 90° is used for larger particles.
NanoBrook 173
Brookhaven's NanoBrook 173 instrument is the go-to-solution for characterization of proteins, antibodies, nanoparticles, macromolecular assemblies and other molecules/particles of small sizes. The NanoBrook 173 uses backscattering detection for the highest sensitivity and accuracy optimized for molecules and particles less than a few tens of nanometers.
NanoBrook 90Plus
The NanoBrook 90Plus particle size analyzer incorporates all you need for fast, routine, sub-micron measurements. Based on the principles of Dynamic Light Scattering (DLS), most measurements only take a minute or two. Choose the optional avalanche photo diode (BI-APD) for weak scatters. The instrument can be upgraded later on to include zeta potential measurement. Please see the 90Plus Zeta and 90Plus PALS for instruments combining sizing and zeta potential.
BI-DCP centrifuge
The Brookhaven BI-DCP is a digitally controlled, high resolution, particle size distribution analyzer. It yields high resolution results in the size range from 0.01 to 30 microns with typical analysis times ranging from 5 to 30 minutes. The DCP softwareprovides easy instrument control, data analysis, and database management. The software is menu-driven and permits a variety of report formats.
Particle Solution software
Designed to operate with NanoBrook series particle characterisation instruments, Particle Solutions software suite integrates characterisation of 5 different particle measurement technologies - DLS, SLS, Phase Analysis Light Scattering (PALS), micro-Rheology and Molecular Weight Determination in one package. The new version of this popular software suite for NanoBrook series particle characterisation instruments includes a host of useful new features. New features include Laboratory Information Management System support, Surface Zeta Potential measurement capability, Multimodal Size Distribution refinement, Health Mode post-measurement analysis, and Statistical Process Control. Safeguarding the investment of existing users - measurements made with earlier versions of the software can be imported into Particle Solutions, and then analyzed with the same powerful tools.
Note: Particle Solutions is only usable with Brookhaven Instruments light scattering systems.
BI-200SM Goniometer System
With a Brookhaven Instruments BI-200SM Research Goniometer System this rich field of exploration is open to you for studies of both Static Light Scattering (SLS) and Dynamic Light Scattering (DLS). The Bl-200SM Research Goniometer System provides access to all of these studies with an automatic,modular and versatile system. It is a precision instrument designed for exacting scattering measurements. Based on a special turntable with precision ball bearings and stepping motor, the Bl-200SM's modern design and quality construction guarantee precise measurements due to the wobble-free movement of the detector. It is field proven in hundreds of laboratories. It is ideal for macro-molecular studies and submicron particle sizing. The BI-200SM's modularity simplifies system expansion. Featuring a standard optical rail, the BI-200SM can be used with neutral density filters, a polarizer, an analyzer, and a reference detector. Special sample requirements can often be met by changing the cell holder design or size.
NEW Particle Explorer Software Suite NEW
NEW Particle Explorer Software for the 200SM Goniometer System for DLS and SLS experiments NEW
BI-MwA 7-Angles MALS Detector
Quickly, easily, and accurately determine absolute molecular weights of proteins and polymers. Eliminate SEC/GPC column calibration and improve data quality. Rapidly reduce uncertainty with no assumptions required and true extrapolation to zero angle. Best of all, the BI-MwA has the highest performance/price ratio of any light scattering detector used for molecular weight determination. There are two ways to use the BI-MwA: Determine the molecular weight distribution (flow mode); or determine the average molecular weight (batch-mode).
UV Detectors provide unsurpassed sensitivity and selectivity as concentration detectors in GPC/SEC. The only limitation is that the sample must contain chromophoric groups and that the solvent used provide a window in the absorption range of UV light. With these conditions fulfilled, a UV Detector is of great use as a single concentration detector in GPC/SEC or, combined with a DRI Detector, for the determination of composition distribution of copolymers. The AYE Rapid Scanning UV combines high sensitivity, a huge linear range of more that 4 orders of magnitude and fl exibility in the application, with solid physical base of clearly defined bandwidth and wavelength precision. It allows detection at two wavelengths, optional four wavelengths, at the same time and is therefore best suited for application where complex copolymers need to be characterized.
ParSEC Advanced GPC/SEC Software
ParSEC is a powerful new suite of software for multi detector, macromolecular characterization and represents the most significant development in GPC/SEC analysis. ParSEC is compatible with ALL GPC/SEC systems and detectors. Many attractive and practical features have been written into the new software for the benefit of chromatographers, including "function specific" views, ensuring the uncluttered display of information relevant to the task at hand, customizable display and annotation options for all graph types, plus a Database approach for practical storage and archiving of data and results associated with any application.
ReadyCal Polymer Standards
GPC/SEC Chromatography is impossible without Polymer Standards. For QC Applications which mostly uses a single concentration detector, Polymer Standards are required for Calibration of the Columns which then allows calculation of Molecular Weights. More complex GPC/SEC Systems with Viscometers and MALS, require Polymer Standards for the determination of Instrument Constants and for System Validation.
These are the facts which make GPC/SEC without Polymer Standards impossible. A ReadyCal™ Kit combines highest quality standards with easy and fast handling, reducing errors in sample preparation practically to zero. Three sets each of four different pre-mixed standards in 1.5 mL screw cap Vials build the strong backbone of a reliable calibration curve. Just add the desired amount of solvent, shake according to instruction and inject. Column calibration cannot be easier.
BI-MwA 7-Angles MALS detector
Quickly, easily, and accurately determine absolute molecular weights of proteins and polymers. Eliminate SEC/GPC column calibration and improve data quality. Rapidly reduce uncertainty with no assumptions required and true extrapolation to zero angle. Best of all, the BI-MwA has the highest performance/price ratio of any light scattering detector used for molecular weight determination.
Differential refractive index GPC/SEC detector
GPC/SEC Chromatography with MALS Detector is a very powerful tool capable of delivering absolute values of the compound under investigation. To achieve this, it is absolutely necessary to obtain concentration data along with the molar mass. In this scenario, a common DRI will lack the capability to deliver data measured at the same wavelength as the laser used in the MALS Detector. This fact will introduce a non-neglectable error in all calculations performed, thus questioning the obtained results. The AYE DRI operates at the very same wavelength your MALS Detector does, thus improving reliability of your results.
ParSEC advanced GPC/SEC software
ParSEC is a powerful new suite of software for multi detector, macromolecular characterization and represents the most significant development in GPC/SEC analysis. ParSEC is compatible with ALL GPC/SEC systems and detectors. Many attractive and practical features have been written into the new software for the benefit of chromatographers, including "function specific" views, ensuring the uncluttered display of information relevant to the task at hand, customizable display and annotation options for all graph types, plus a Database approach for practical storage and archiving of data and results associated with any application.
ReadyCal polymer standards
GPC/SEC Chromatography is impossible without Polymer Standards. For QC Applications which mostly uses a single concentration detector, Polymer Standards are required for Calibration of the Columns which then allows calculation of Molecular Weights. More complex GPC/SEC Systems with Viscometers and MALS, require Polymer Standards for the determination of Instrument Constants and for System Validation.
These are the facts which make GPC/SEC without Polymer Standards impossible. A ReadyCal™ Kit combines highest quality standards with easy and fast handling, reducing errors in sample preparation practically to zero. Three sets each of four different pre-mixed standards in 1.5 mL screw cap Vials build the strong backbone of a reliable calibration curve. Just add the desired amount of solvent, shake according to instruction and inject. Column calibration cannot be easier.
Introduction
GPC/SEC Chromatography with MALS Detector is a very powerful tool capable of delivering absolute values of the compound under investigation. To achieve this, it is absolutely necessary to obtain concentration data along with the molar mass. In this scenario, a common DRI will lack the capability to deliver data measured at the same wavelength as the laser used in the MALS Detector. This fact will introduce a non-neglectable error in all calculations performed, thus questioning the obtained results. The AYE DRI operates at the very same wavelength your MALS Detector does, thus improving reliability of your results.
BI-MwA 7-Angles MALS Detector
Quickly, easily, and accurately determine absolute molecular weights of proteins and polymers. Eliminate SEC/GPC column calibration and improve data quality. Rapidly reduce uncertainty with no assumptions required and true extrapolation to zero angle. Best of all, the BI-MwA has the highest performance/price ratio of any light scattering detector used for molecular weight determination.
ParSEC Advanced GPC/SEC Software
ParSEC is a powerful new suite of software for multi detector, macromolecular characterization and represents the most significant development in GPC/SEC analysis. ParSEC is compatible with ALL GPC/SEC systems and detectors. Many attractive and practical features have been written into the new software for the benefit of chromatographers, including "function specific" views, ensuring the uncluttered display of information relevant to the task at hand, customizable display and annotation options for all graph types, plus a Database approach for practical storage and archiving of data and results associated with any application.
ReadyCal Polymer Standards
GPC/SEC Chromatography is impossible without Polymer Standards. For QC Applications which mostly uses a single concentration detector, Polymer Standards are required for Calibration of the Columns which then allows calculation of Molecular Weights. More complex GPC/SEC Systems with Viscometers and MALS, require Polymer Standards for the determination of Instrument Constants and for System Validation.
These are the facts which make GPC/SEC without Polymer Standards impossible. A ReadyCal™ Kit combines highest quality standards with easy and fast handling, reducing errors in sample preparation practically to zero. Three sets each of four different pre-mixed standards in 1.5 mL screw cap Vials build the strong backbone of a reliable calibration curve. Just add the desired amount of solvent, shake according to instruction and inject. Column calibration cannot be easier.
The specific refractive index increment (dn/dc) is one of the values required for the determination of absolute molecular weight with Static Light Scattering (SLS). The importance of this parameter becomes clear when observing the composition of the Debye Constant used for calculations, where the dn/dc is a squared term. As such, a relatively small error in dn/dc will lead to twice the error in molecular weight. It is important to notice that the dn/dc value must be obtained at the same wavelength as the Laser used for Light Scattering or a further unknown error will be introduced. Determination of the specifi c refractive index (dn/dc) of any dissolved sample can be easily achieved in batch mode with the AYE dn/dc Refractometer, with just a few syringes needed. Measurement of a set of concentrations of the sample under investigation with the AYE dn/dc Refractometer will lead to reliable and reproducible results within minutes. A huge number of wavelength options are available to perfectly match the Laser used in SLS, making sure your results will be perfect.
BI-MwA 7-Angles MALS Detector
Quickly, easily, and accurately determine absolute molecular weights of proteins and polymers. Eliminate SEC/GPC column calibration and improve data quality. Rapidly reduce uncertainty with no assumptions required and true extrapolation to zero angle. Best of all, the BI-MwA has the highest performance/price ratio of any light scattering detector used for molecular weight determination. There are two ways to use the BI-MwA: Determine the molecular weight distribution (flow mode); or determine the average molecular weight (batch-mode).
Interview: Insights from Industry
Why are Testa Analytical involved in polymer characterization and particle sizing? In the eyes of Testa Analytical polymer characterization in terms of chromatography and particle sizing using DLS are just two ways of looking at the same subject. We look at the same material from two different points of views which in turn gives us a better understanding of the whole material which is exactly what Testa Analytical strives to provide the solution for.
Common detectors for GPC/SEC Chromatography
This article provides an overview about the detectors most commonly used in GPC/SEC applications, explains differencies within each detector class, provides inforamtions about pro's and con's of each detector and also explores combination of detectors for the most useful hyphenated techniques in GPC/SEC.
Determination of specific refractive index increment (dn/dc)
The specific refractive index increment (dn/dc) is a fundamental parameter for the determination of molecular weight with Static Light Scattering. Its importance will become clear by observation of the Debye's constant in the SLS equation, where the dn/dc is a squared term. As such, any error in the specific refractive index increment will strongly effect the molecular weight results. This is true for both cases, when SLS is used in batch mode, like in case of a goniometer system, or in flow mode like in case of a MALS Detector in GPC/SEC. This work explains and shows how dn/dc can be determined with extremely high accuracy with help of a specialized dn/dc Refractometer and Software.
Guide for DLS sample preparation
This document is intended to help the user determine the best way to prepare samples for dynamic light scattering (DLS) measurements. If the user wants to know how to prepare the 92nm latex standard for best measurements, please refer to the document entitled "A Guide to Proper Sample Preparation: Electrostatically-Stabilized Nanoparticles in Water.”
Particle Sizing using DCP for ASTM Carbon Black
The principles of particle sizing using a disc centrifuge photosedimentometer are reviewed. The importance of the extinction correction for accurate measurements is emphasized. Results on the ASTM A4 through F4 series of reference blacks is presented. Comparisons between reference materials are made. Different sample preparations are discussed. Stability of such preparations with time is shown.
Studying Protein Aggregation Using ASEC
Exploiting the potential of protein therapeutics requires the ability to identify and quantify the protein aggregation that can yield inconsistent activity and provoke immune response. The sensitivity of light scattering to small numbers of large particles (aggregates) makes light scattering an unsurpassed tool for studying aggregation.
New advances in the Zeta Potential measurements of proteins
Introduction Stability of protein formulations is of critical importance for the rapidly emerging areas of protein therapeutics and vaccine production from recombinant antigens. Zeta potential, or the surface charge density at the shear plane, is one of the parameters used in predicting the stability of these preparations. Zeta potential has also been used as an indication of conformational changes in response to ligand addition. Traditional means of zeta potential measurements have employed classical laser Doppler velocimetry to derive the electrophoretic mobility of suspended proteins.
A Guide to Proper Sample Preparation
Introduction: Sample preparation is the most important step in obtaining the best results for both dynamic and static light scattering. While the instrument or software is the easiest to blame for poor results, improper sample preparation is usually the culprit. This guide will outline in detail the steps necessary to acquire relatively dust-free samples.
A Guide to Determination of Particle Size
When any material of one phase is dispersed into a second phase, an “interface” is created between the two phases (1). The total extent of this interface, which will depend on exactly how the dispersion is made (2), controls the fundamental behavior (stability and structure) of the dispersion. And, it applies equally to particles in air as to particles in liquids.
A guide to choosing a Particle Sizer
Introduction: The choice of a particle Size analyzer has never been more difficult. There are several techniques from which to choose and variations within each technique. Sales literature claims of specification and performance have become highly inflated, confusing the first-time buyer; the result has been to hinder and not help the decision-making process. Many particle sizing instruments were originally designed to address specific problems. Although some have found additional uses, there is still some truth to the notion that certain techniques are best suited for particular tasks. The idea that one instrument will suit every particle sizing need, and hence solve all problems, is not supported in practice.
What is Particle Size Distribution Weighting
Introduction: Some particle size instruments determine the size of individual particles. They are single-particle counters. Some instruments determine the surface area as a function of particle size. Some instruments determine mass or volume vs size. And some instruments determine various functions of scattered light intensity as a function of size. All can produce particle size distributions. And, in principle, one can transform from one type to the other in order to compare results. For example, if a measurement with a single particle counter produced a differential number-weighted Size distribution and you wanted to compare the results to a measurement with another type of instrument that produced a differential volume-weighted size distribution, what would you do?
What is a particle
Elementary vs Fine Particles: The question embodied in the title might seem strange until you consider the many different ways particles play a part in science and engineering. For example, if you do a web search using just the word particle, you will get more hits for atomic, nuclear, and elementary or subatomic particles than you will for pharmaceutical particles, nanoparticles, clay particles, etc. You will get a lot of hits for particle accelerators, particle colliders, particle physics as well as a few hits that really interest you.
Characterising Liposomes & Liposome-drug Conjugates
Liposomes or Lipid-drug conjugates used as targeted drug delivery systems are hot topics in the field of pharmaceutical research. The size and charge at the surface of the particle plays a deciding role for proper gastrointestinal uptake of the synthesized Liposome Drug Conjugates (LDC) nanoparticles and their systemic clearance by the reticuloendothelial system. It is therefore always important to determine the size of LDC nanoparticles accurately. A new application note is available describing how the Nanobrook ZetaPALS instrument, using a phase analysis light scattering technique, has been used to accurately determine the size and surface charge of liposomes, exosomes and microvesicles.
Aggregation Detection by Dynamic Light Scattering
Testa Analytical Solutions e.K reports on how its NanoBrook Omni particle size analyser and BI-ZTU autotitrator can be used together to detect the onset of aggregation in nanoparticles. The NanoBrook Omni instrument offers a single powerful and accurate solution for particle sizing and zeta potential analysis. The instrument allows users to measure samples in nearly every possible suspension environment from high salts such as PBS and sea water to organic solvents and aqueous solutions. The instrument offers unmatched particle sizing, with the highest sensitivity, utilizing three light scattering measurement angles for truly unbiased measurement results. The BI-ZTU autotitrator option for the NanoBrook Omni provides an ideal solution for automated measurement of particle size as a function of pH.
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TESTA Analytical Solution is a manufaturer and supplier of analytical instrumentation for polymer characterization, particle sizing and zeta-potential measurements. Our portfolio covers our line of GPC/SEC Chromatography equipment, developed and manufactured in Germany, and the full product range of Brookhaven Instruments Corp.including research grade Static Light Scattering (SLS) instruments known as goniometers, MALS Detectors for GPC/SEC, Dynamic Light Scattering (DLS) devices, analytical centrifuges with visible and x-ray sources and instruments for the determination of Zeta-Potential with both ELS and PALS methods.
TESTA Analytical Solutions also offers replacement parts, accessories, maintenance, validation and repair service for all products in the portfolio and, in rare cases, for third-party products.
Talk to us, we create Solutions.
By experience we know that any application, no matter how similar to others it might seem to be, is a challenge by its own, requires specific attention and a taylored solution. We also know that technology by itself will not solve any problem; Users solve problems by understanding and applying the technology appropriate to the problem. We help users selecting the right technology and discuss the practical use of it including interpretation of results. We supply knowledge accumulated in the past 30 years of operation in polymer characterisation and particle sizing. 
The columns in a size exclusion or gel permeation chromatography experiment fractionate the injected solution as the pump keeps the eluent flowing at a constant rate. A simple Setup utilizing a concentration Detector like DRI or UV, will allow determination of relative molecular weights, relative because dependent on the polymer standards used to calibrate the system. With an SLS detector, the intensity and Rayleigh ratio are determined. Add a concentration detector, mostly a DRI, and Debye’s equation can be used to determine Mw, if and only if the excess scattering is high enough. A viscosity detector (mostly called viscometer) in combination with a concentration detector, will however allow construction of a universal calibration. While molecular weights obtained with this method are not strictly absolute, the values obtained are indipendent of the polymer standards used to calibrate the system. 
Debye made the first measurements of the weight-average molecular weight, MW, of small polymers. As long as the radius of gyration, Rg (a z-average if there is a distribution of chain lengths), is less than about 12 nm, the polymer or protein acts like a point dipole when it comes to scattering the electric field of the light source. Within a few years of Debye’s first paper, the interference effect from larger molecules and particles on SLS was developed and with it a means to determine size in the form of Rg. For batch-mode, SLS measurements, an instrument with half a dozen or more angles spread from 30° to 150° offers all the flexibility required for multi-angle SLS and the determination of most Rg values. Single angle devices can never be used to determine Rg. The overwhelming majority of manufactured industrial products and increasingly those for healthcare purposes involve, either in the final state or at some stage of their production, suspensions of particulate materials; indeed, nanoparticulate dispersions are typically created in situ. The importance of the process of dispersion and its profound effect on the economics and quality of the subsequent product has long been recognized. Thorough characterization of particulate suspensions is, therefore, paramount in obtaining optimum performance features and cost effective benefits from such systems. 
Zeta potential is the charge that develops at the interface between a solid surface and its liquid medium. This potential, which is measured in MilliVolts, may arise by any of several mechanisms. Among these are the dissociation of ionogenic groups in the particle surface and the differential adsorption of solution ions into the surface region. The net charge at the particle surface affects the ion distribution in the nearby region, increasing the concentration of counterions close to the surface. Thus, an electrical double layer is formed in the region of the particle-liquid interface. 
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