Tag Archives: Laser Diffraction

5 Fascinating Careers in Industrial Science

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Careers in industrial science continue to expand with positions opening up in both government and private institutions, especially in the area of research and manufacturing. Graduates can choose from a range of careers in agricultural and biological sciences, the information and technology sector, food and pharmaceutical companies, as well as mining and mineral exploration.

With the unparalleled expansion of scientific knowledge, industrial scientists have the opportunity of working at the leading edge of scientific developments no matter whether they have a leaning towards biology, chemistry or physics.

There will be a career path in industrial science in a variety of fields, and this article looks at five fascinating careers to consider.

1. Industrial Microbiology

If you have a penchant to work in a multidisciplinary scientific environment, then industrial microbiology or biotechnology could interest you. Processes and production problems often take scientists in a variety of directions which means that an industrial microbiologist has to be adaptable across such fields as bioengineering, biochemistry and molecular biology. Career pathways can lead you into fields such as antibiotics and vaccines as well as many other healthcare products and even food and beverages which are produced by microbial activity, for instance, cheeses, yoghurts.

2. Environmental Engineering

Environmental engineering suits graduates who are concerned about the man-made environment and issues relating to water quality, waste disposal, air quality and dealing with contaminated land. Today, research into the prevention of pollution is supported by government and private agencies alike and graduates can expect to work with mechanisms of sustainability in either private companies or government research facilities.

3. Chemical Engineering

Chemical engineering provides a practical link between the theory of science and manufacturing. Industrial scientists with a preference for working in this area will be involved in designing of equipment and development of large chemical manufacturing processes in a variety of industries including photography and photographic equipment, manufacturing chemicals and health care products

4. Academic Research

Most academic careers in the area of industrial science will attract high achieving practitioners looking to develop their research and, naturally, to teach within universities. Professorial appointments are highly regarded and provide satisfying careers for experienced scientists. Although opportunities are limited, with the expansion in industrial scientific jobs as a whole, academic posts are becoming more frequently advertised.

5. Nanotechnology

Within the emerging realm of nanotechnology, jobs are being created across a diverse range of activities. From creating cosmetics and researching the nature of matter, to medical diagnostics and developing better batteries are just a few opportunities that provide blossoming careers for industrial scientists. It is safe to say there is a revolution in manufacturing and in production of new materials. The new ways in which these are made is largely under the direction of a highly qualified industrial scientist. You could find yourself working for a sports equipment company or the army. The choices are almost endless.

Industrial Science Growth

The outlook for employment in the area of industrial science is rapidly increasing. Government predictions of job growth show that this growth will continue for at least the next three years unabated. Even in times of slower employment growth, it is apparent that many companies will continue to research and develop new products requiring industrial science expertise.

Your future

Regardless of the field chosen, most people working in industrial science will gain first hand experience with cutting edge analytical measurement techniques. Measurement technologies such as Laser Diffraction, Dynamic Light Scattering, Spectroscopy, HPLC and Rheology are widely used in industrial science jobs. With the help of these cutting-edge technologies supplied by ATA Scientific, people around the world are expanding development of exciting new products that will shape our future world.

Looking for the perfect analytics instrument for YOUR next big discovery?

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3 Things to Consider when Purchasing a Quartz Crystal Microbalance

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A quartz crystal microbalance or QCM measures a mass per unit area by measuring the change in frequency of a quartz crystal resonator. The sensor, which is the crystal, oscillates at a constant frequency and as the mass on the crystal changes, so does the resonance frequency. The addition or abstraction of the mass is due to oxide growth or film deposition at the surface of the acoustic resonator. The QCM works under vacuum, in gas and even in liquid environments. Under vacuum, it is useful for monitoring the rate of deposition in thin film deposition system and in liquid; it is effective at determining the affinity of molecules to surfaces functionalised with recognition sites. Simply put, QCM is the mass measurement standard, just as laser diffraction is essential for the measurement of particle size.

A basic QCM includes a source of alternating current — the oscillator, a quartz crystal, two metal electrodes on opposite sides of the thin crystal wafer and a frequency counter. According to most experts, choosing a QCM is a matter of finding the right match for the analytical objective and sample conditions. There are however, three important things that play critical roles in the equipment’s functionality that you should consider.

1. The Crystal

There are a few parameters that you have to determine when purchasing QCM crystals.

Frequency

Although higher frequencies will provide better resolution, these crystals will be more difficult to handle. A crystal’s frequency ranges from 1.00 to 30.000MHz.

Blank Diameter

The standard blank diameters are .538”, .340” and .318”.

Electrode Diameter

The electrode diameters available include aluminium, carbon, chromium, cobalt, copper, molybdenum, nickel, palladium, platinum, silicon, silver, tin oxide, titanium, tungsten, zinc.

Mounting and Bonding

While most crystals will be bonded to a base that provides a physical and electrical connection, you may request for the crystals to be un-bonded and coated with material from your facility.

2. Crystal Accessories

For a QCM crystal to work, you must have some type of oscillator circuit to enable a connection. In most cases, an enclosure or liquid/static cell for the crystal is necessary. There are two main types of high-quality oscillators specially designed for use with QCM crystals. They are standard (clock) oscillators used in gaseous applications and lever oscillators used in liquid applications.

3. QCM Components

In addition to the crystals, there are also a variety of components to complement the QCM. Some components are limited to manual control while others have different levels of electronic module. A QCM with the additional measurement of dissipation is called QCM-D. Dissipation provides information about the structure and viscoelasticity of the film. The measurement of particle size which can be done with a particle size analyzer and the study of surface properties are essential for a better understanding of the way in which materials interact, making the QCM-D very useful and effective as it is a real-time, label-free, surface-sensitive technique.

Microscopy

QCM-D can be combined with light microscopy using the window module. This visual entry allows correlation of real-time microscopy to changes in mass and viscoelastic properties. Studies of light-induced reactions and cell adhesion are also enabled.

Electrochemistry

As electrochemistry and QCM-D are surface techniques, they form an ideal pair. Electrochemistry can be the stimulus of an interaction or provide information about interfacial charge transfer while QCM-D can provide real-time information on mass and structure of these films. One such application is electrostatic interactions of biomolecules with surfaces.

Make an informed purchase

Do you need a Quartz Crystal Microbalance for your processes? ATA Scientific offers quality scientific instruments and can help you decide which instrument best fits your needs. Contact ATA Scientific today.

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Protein Analysis Techniques Explained

Biomolecular Science - Guide,

Proteins Explained

Proteins, also known as polypeptides, are organic compounds made up of amino acids. They’re large, complex molecules that play many critical roles in the body.

Proteins are made up of hundreds of thousands of smaller units that are arranged in a linear chain and folded into a globular form. There are 20 different types of amino acids that can be combined to make a protein and the sequence of amino acids determines each protein’s unique 3-dimensional structure and its specific function.

Proteins do most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs. Essential parts of organisms, they participate in virtually every process within cells. Many proteins are enzymes that catalyse biochemical reactions and are vital to metabolism. The size of a protein is an important physical characteristic and scientists often use particle size analysers in their studies to discuss protein size or molecular weight.

THE STRUCTURE OF PROTEINS

To be able to perform their biological function, proteins fold into one or more specific spatial conformations driven by a number of non-covalent interactions such as hydrogen bonding, ionic interactions, Van der Waals forces, and hydrophobic packing. This understanding is the topic of the scientific field of structural biology, which employs traditional techniques such as X-ray crystallography, NMR spectroscopy, and Circular Dichroism spectrometry to determine the structure of proteins.

Most proteins fold into unique three-dimensional structures. The shape that a protein folds into naturally is known as its native conformation. While most proteins can fold unassisted through the chemical properties of their amino acids, others require the aid of molecular chaperones. There are four distinct aspects of a protein’s structure:

  • Primary structure: The amino acid sequence.
  • Secondary structure: Regularly repeating local structures stabilised by hydrogen bonds.
  • Tertiary structure: The overall shape of a single protein molecule; the spatial relationship of the secondary structures to one another.
  • Quaternary structure: The structure formed by several protein molecules which function as a single protein complex.

Protein structures range in size from tens to several thousand amino acids. By physical size, proteins are classified as nanoparticles, between 1 – 100nm. Very large aggregates can be formed from protein subunits. For example, many thousand actin molecules assemble into a microfilament.

TRADITIONAL PROTEIN ANALYSIS TECHNIQUES

Proteins differ from each other according to the type, number and sequence of amino acids that make up the polypeptide backbone. Hence, they have different molecular structures, nutritional attributes and physicochemical properties.

There are three major protein analysis techniques: protein separation, western blotting and protein identification.

1. PROTEIN SEPARATION

Protein electrophoresis is the process of separating or purifying proteins by placing them in a gel matrix and then observing protein mobility in the presence of an electrical field. It’s an important approach to studying protein function and the effect of a particular protein on development or a physical function by introducing it into an organism.

The most commonly used technique for protein separation is sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Proteins can be separated according to solubility, size, charge and binding affinity. SDS-PAGE separates proteins mainly on the basis of molecular weight as opposed to charge or folding. It’s a technique that’s widely used in biochemistry, forensics, genetics and molecular biology.

Other methods include:

  • Isoelectric Focussing: In this method, different molecules are separated by their electric charge differences. This technique is a type of zone electrophoresis that is usually performed in a gel and takes advantage of the fact that a molecule’s charge changes with the pH of its surroundings.
  • Chromatic Methods: There are two chromatic methods frequently used for protein separation – high-performance liquid chromatography and thin-layer chromatography. Both these methods are particularly useful adjuncts to gel-based approaches. Although chromatography is a common technique in biochemistry laboratories used for purification, identification and quantification of protein mixtures, laser diffraction is traditionally used for pre-column size and polydispersity management.
  • Two-dimensional Gel Electrophoresis: This is a powerful gel-based method commonly used to analyse complex samples in the interest of characterising the full range of proteins in the sample, not just a few specific proteins.

2. WESTERN BLOTTING

The western blot technique uses three elements to identify specific proteins from a complex mixture of proteins extracted from cells: separation by size, transfer to a solid support, and marking target protein using a proper primary and secondary antibody to visualise.

The most common version of this method is immunoblotting. This technique is used to detect specific proteins in a given sample of tissue homogenate or extract. The sample of proteins is first electrophoresed by SDS-PAGE to separate the proteins based on molecular weight. The proteins are then transferred to a membrane where they are probed using antibodies specific to the target protein.

3. PROTEIN IDENTIFICATION

There are two methods that are commonly used to identify proteins: Edman Degradation and Mass Spectrometry.

Developed by Pehr Edman, Edman Degradation is a method of sequencing amino acids in a peptide. Here, the amino-terminal residue is labeled and cleaved from the peptide without disrupting the peptide bonds between other amino acid residues.

Protein Mass Spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles for determining masses of particles and the elemental composition of a sample of molecules as well as for elucidating the chemical structure of molecules such as peptides. Protein mass spectrometry is an important method for the accurate mass determination and characterisation of proteins, and a variety of methods and instrumentations have been developed for its many uses. The application of mass spectrometry to study proteins became popularised in the 1980s after the development of MALDI and ESI. These ionisation techniques have played a significant role in the identification of proteins. Identification can be made via:

  • Peptide mass fingerprinting uses the masses of proteolytic peptides as input to a search of a database of predicted masses that arise from digestion of a list of known proteins. The main advantage of this method is that it doesn’t depend on protein sequencing for protein identification. The limitation of this method is that it requires the database to have the protein which is already characterised on another organism.
  • De novo peptide sequencingis performed without prior knowledge of the amino acid sequence. This method can obtain the peptide sequences without a protein database and uses computational approaches to deduce the sequence of peptide directly from the experimental MS/MS spectra. It can be used for unsequenced organisms, antibodies, peptides with posttranslational modifications (PTMs) and endogenous peptides.

MODERN PROTEIN ANALYSIS TECHNIQUES

Protein complex analysis involves extensive interpretation of the structure and function of proteins, which are present in complex biological samples. Though recent protein complex analysis methods are efficient in identifying the structure of protein complex, there are some limiting factors.

The ever-increasing number of alternative ways to detect protein-protein interactions (PPIs) speaks volumes about the creativity of scientists in hunting for the optimal technique. Modern techniques are continually allowing us to study protein more effectively, efficiently and at reduced costs and include:

1. LIGHT SCATTERING

Light scattering techniques are particularly sensitive to larger molecules in preparations of smaller molecules. Any increase in the size of a protein will most likely be the result of aggregate formation. The sensitivity of the light scattering measurement to larger proteins means that the earliest stages of denaturation, leading to the formation of a few aggregates, will result in changes in the mean hydrodynamic size.

Batch Dynamic Light Scattering (DLS): Size measurement is the primary measurement of proteins that can be performed with batch-mode DLS. Since proteins have a very consistent composition and fold into tight structures, the hydrodynamic size relates predictably with molecular weight. The activity and function of a protein is closely related to correct folding and structure. As such, activity is also directly related to the size of the protein, meaning size can also be used as a predictor of activity. DLS the most sensitive technique for detecting small quantities of aggregates in preparations. Zetasizer software has a model to predict the molecular weight of a protein from its hydrodynamic size by DLS. Request a demo.

Static Light Scattering (SLS): Following on from DLS measurements, SLS measurements can also be made of proteins. Often highly purified, many protein samples should be applicable for batch measurements of molecular weight using SLS, as long as the concentrations are accurately known. By measuring the amount of light scattered at different concentrations of sample, the molecular weight, which is proportional to the amount of light scattered, can be calculated by creating a Debye plot. The slope of the line in the Debye plot is 2x the 2nd virial coefficient (a measure of molecular interaction within a solution) so this technique can also be useful for studying crystallisation conditions. A strongly positive value indicates good solubility while a strongly negative value indicates a propensity to aggregate. Request a demo.

Charge and Zeta Potential: Using a suitably sensitive instruments such as the Zetasizer Ultra, and an appropriate method such as the patented diffusion barrier technique, Zeta-potential measurements of proteins are also possible. A significant number of the functional groups on amino acids can be charged and any combination of these may be in their charged or uncharged states in the protein. This will change depending on the conditions in the local environment and it is important to note that zeta-potential can be different from the calculated net charge based on the likely state of the charged residues in the molecule.

Charge is of particular interest to protein chemists and Zeta potential should be able to compete with iso-electric focusing, currently one of the primary methods for determining protein charge, as it allows the protein to be kept in conditions far nearer to its native state. It should be noted, however, that proteins are subject to being denatured by the applied electric field, which can make zeta-potential measurements difficult. The diffusion barrier technique is a method that’s used to reliably measure the electrophoretic mobility of proteins by reducing the impact of the measurement process. For more information, contact us.

Overall, Zeta potential is a measure of the strength of the repulsive forces between molecules in solution. Conventionally, this has been used as a primary indicator of the stability of a sample preparation. With high Zeta potential, and consequently, high intermolecular repulsive force, a drug or protein preparation can be expected to be stable for longer periods than a similar preparation with low Zeta potential. Request a demo.

2. MULTI-DETECTION GPC/SEC

While DLS can be used to characterise the oligomeric state of a protein, it is unable to resolve a mixture of oligomers. Adding SEC capabilities to a light scattering detector is a way to greatly improve its resolution.

The Malvern OMNISEC Resolve and Reveal system separates molecules based on their size making it an excellent partner for light scattering. By separating the molecules before measuring them, using DLS or SLS, this technique can be used to identify the different components in a mixture. At known concentrations, measured with a refractive index or a UV detector, molecular weight can be related directly to the amount of light scattered by a molecule. This can be combined with data from a viscometer, which measures viscosity allowing size and some structural aspects to be determined. Thus, a large amount of information can be obtained for a single protein sample using this method.

The Malvern OMNISEC also adds another dimension to the detection of aggregates. By separating them from the primary sample, it’s possible to further characterise and quantify them. Manufacturers of protein solutions routinely use SEC as the final step in purification. SEC is used to separate samples in order to remove any aggregates formed in the sample preparation. The same is true when purifying a single protein from biological samples. Request a demo.

3. Circular Dichroism Spectrometry

Circular Dichroism (CD) is an absorption spectroscopy method based on the differential absorption of left and right circularly polarized light. Optically active chiral molecules will preferentially absorb one direction of the circularly polarized light. The difference in absorption of the left and right circularly polarized light can be measured and quantified. UV CD is used to determine aspects of protein secondary structure. Vibrational CD, IR CD, is used to study the structure of small organic molecules, proteins and DNA. UV/Vis CD investigates charge transfer transitions in metal-protein complexes.

JASCO J1000 series CD spectrometers provides maximum signal-to-noise under high absorbing, low light intensity conditions of the far-UV spectral region to explore the structure and stability of biomolecules. It provides unparalleled optical performance and versatile flexibility for advanced biomolecular characterisation and stereochemical analysis. The Dual Polarizing Prism Monochromator covers the entire region required for routine analysis of biomolecules with excellent stray-light rejection for accurate results. Enhanced vacuum UV measurement enables the measurement of a CD spectrum in the vacuum UV region can go down to 163nm which is of critical importance for biomolecules. Request a demo

4. Isothermal Titration Calorimetry

Isothermal titration calorimetry (ITC) is a physical technique used to determine the thermodynamic parameters of interactions in solution. It is most often used to study the binding of small molecules (such as medicinal compounds) to larger macromolecules (proteins, DNA etc.). It consists of two cells which are enclosed in an adiabatic jacket. The compounds to be studied are placed in the sample cell, while the other cell, the reference cell, is used as a control and contains the buffer in which the sample is dissolved.

The MicroCal PEAQ-ITC offers the highest sensitivity for label free measurements of binding affinity and thermodynamics with low sample consumption for the study of biomolecular interactions. It delivers direct measurement of all binding parameters in a single experiment and can analyze weak to high affinity binders, using as little as 10µg sample. Semi-automated maintenance minimizes operator intervention and the system is upgradable to the fully automated MicroCal PEAQ-ITC Automated, making it ideal for laboratories where speed, sensitivity and the ability to accommodate higher workloads in the future are paramount. Request a demo

PROTEIN ANALYSIS MADE EASY

Crystallisation of proteins is a necessary step for elucidating their detailed 3-dimensional structure. Crystallisation is a difficult process that requires a highly purified protein kept in ideal conditions. In DLS measurements, polydispersity is a measure of the purity of a sample. A protein sample with a very low polydispersity indicates that it is highly purified, that all the protein is in one particular oligomeric conformation and that its structure is very well controlled under these conditions, all of which are required for crystallisation. By identifying a protein sample with the lowest polydispersity, a researcher can find the most suitable conditions for crystallisation.

Size can also be used as a predictor of activity and quaternary structure of the protein can also be studied. When proteins oligomerise, their size and molecular weight will increase in discrete increments corresponding to the addition of separate proteins. By measuring the protein under different conditions the oligomeric state of the protein can be assessed. Many proteins rely on correct quaternary structure in order to function, so again, hydrodynamic size can be used as a predictor of activity.

In adverse conditions such as extremes of temperature and pH, a protein will become denatured. By controlling these conditions, and measuring the hydrodynamic radius, the melting point of the protein can be established. This is related to the stability of the protein and can be used as a predictor of shelf life.

Need the right tools for measurement? ATA Scientific offers a comprehensive toolbox for analysing proteins in a number of ways, including Multi detection GPC/SEC, Circular Dichroism (CD), Microcalorimetry (ITC/ DSC), Dynamic and Static light scattering (DLS/ SLS) and more. Contact us today for a free consultation and make protein analysis easy. We provide the instruments and ongoing support so that you can be confident in your results.

4 Benefits of On-Line Particle Analysis for Mineral Processing

Particle Science - Guide, , , ,

In order to extract valuable minerals from naturally occurring ores, the process of comminution and milling must take place to produce materials of an appropriate particle size. This process is critical in order to ensure operating costs stay low and to ensure the minerals extracted are of high value. Traditionally, particle size analysis has been performed through manual measurement, but increasingly the industry is turning towards on-line particle size measurement methods such as laser diffraction. In this article, we’ll look at four reasons that laser diffraction is the optimum method for particle sizing in the mineral processing industries.

1. Quicker and higher ROI

Most studies have confirmed that return of investment for on-line laser diffraction occurs anywhere between six months and a year following installation. The biggest reason for this is that there is much less reliance on manpower; manual analysis methods generally necessitate highly-skilled individuals to be working around the clock, while on-line systems only require occasional intervention from a semi-skilled worker, lowering costs in terms of both time and expertise. These lowered man hours have the added benefit of minimising the risk of hazard material exposure.

2. Greater levels of process control

With off-line measurement, the frequency of analysis is quite low, occurring an average of once or twice an hour. This has the flow-on effect that operational changes are bound to be much less frequent; the operator will receive the data and make a change (perhaps a very large change), and won’t see the outcome of that change until the next analysis. With online particle size analysis, however, there is a constant flow of information, meaning that smaller changes can be made on a more consistent basis.  Additionally, the on-line method of measurement allows for a steadier stream of automated control. Both of these factors lead to more efficient process control.

3. Faster process optimisation

Since finding the optimal particle size is crucial to extracting the most valuable from the ore, the optimal processes must be put in place. Much like discussed above, off-line particle size analysis requires the analyst to wait until several samples have been taken and analysed before they can see the outcomes of their changes. With an on-line particle size analyser, however, this process is much quicker. Assessing new operating scenarios requires nothing more than a new steady state to be established, meaning the changes can be evaluated in minutes.

4. Immediate upset detection

The impact of an upset can be disastrous for the batch, leading to significant loss of profit. To avoid this kind of situation, it’s important to detect problems as soon as possible. With off-line particle size measurement, problems can go undetected for hours, but with on-line methods such as laser diffraction, there is constant monitoring of the process and upsets can be detected as they occur. Rio Tinto, for example, has enjoyed a two year period without unplanned stoppages, and it’s all thanks to their installation of an on-line particle size analyser. Problems are detected and the appropriate action is taken to remedy the situation before it escalates.

What is Particle Size Analysis?

Particle Science - Guide, , , ,

Particle size analysis: it sounds tricky, but mark our words, it’s something that everyone would be well-served learning more about. Whether you realise it or not, particle size analysis plays an extremely important role in many of the products we use, consume and interact with in our everyday lives. In this article, we’re going to offer you a brief introduction to particle size analysis, listing some of its most common applications as well as its most established methods. We’ll also take a look at zeta potential, a measurement that is often used along side particle size analysis.

What is particle size analysis?

There are a huge number of industries which rely on methods of particle size analysis to ensure products are of the highest quality. From powders to creams, gels, lotions, and other mixtures, the size and characteristics of the particles contained within can have dramatic effects on properties such as stability, appearance, flow and chemical reactivity. As a result, a highly important industry has developed centred on particle size analysis, with constant innovation in methods that provide more and more accurate ways of analysing particle size.

What are the applications of particle size analysis?

As we’ve already mentioned, the applications of particle size analysis are numerous; too numerous to mention here. However, some of the industries that rely heavily on the understanding of particle size distribution include:

  • The cosmetics industry
  • The pharmaceutical industry
  • The cement industry
  • The food and beverage industry
  • The plastics industry
  • The pigments and inks industry
  • The ceramics industry
  • The metal powders industry

What are some common particle size analysis methods?

Probably the most popular method of particle size analysis is laser diffraction , which involves particles being illuminated by a laser beam, causing the light to be scattered in various directions. The scattering patterns are then measured with specially-designed detectors and particle size distribution can be calculated from this data. For example, larger particles bring about a higher intensity of scattering at lower angles to the beam, while smaller particles offer a low intensity of scattering at higher angles.

Laser diffraction has the advantage of offering real-time particle analysis that allows for several benefits, including:

  • Increased return of investment
  • Lower energy consumption
  • Better troubleshooting
  • Increased efficiency
  • Reduced operator risk

What is Zeta Potential?

When measuring particle size distribution, it’s also important to consider the particle’s zeta potential or ‘charge’ measurement. Most particles will gain a charge on their surface when dispersed in an aqueous system. These charges change the distribution of the surrounding ions, leaving a layer around the particle that does not have the same properties as the rest of the solution. Zeta potential determines how particles interact within solution and measurement of zetapotential can give valuable insight into stability and reactivity of a material.

The Best Ways to Measure and Analyse Particles

Particle Science - Guide,

For many people, the thought of measuring and sizing particles (that are often too small to be visible) can seem completely baffling. Just the thought of how this could possibly be done can seem daunting.

These days there are several types of particle size analyser instruments available that operate using different measurement techniques. laser diffraction is one such technique that can give us great insight into the properties of different materials.

Of course, there is no single measurement technique that can be used to measure all materials and all particle sizes. As such, some industries use a range of different techniques to measure different materials.  The problem with this is that different techniques measure different dimensions of particles, so when they often yield different results.

In order to understand more about the different results that are obtained through particle measurement and analysis, it is useful to be aware of some commonly used methods. These include:

Sieves:

This is one of the oldest and most traditional of all the methods of measuring particle size and is so often used because it is cheap and reasonably effective when measuring larger particles. The measurement of large particles occurs in a number of industries, including the mining industry.

However, the use of a sieve makes it impossible to measure particles within sprays or emulsions.  Even dry powders become very difficult to measure when particle are very fine. A further disadvantage is that the ability to reproduce results is difficult, particularly when the technique of wet sieving is applied.

In order for particle size results from sieves to be useful and informative, the operating methods and measurement times need to be standardised.

Sedimentation:

This is another technique which has been around for a long time and has historically been used in certain industries.  Soil scientist have long used sedimentation to measure course grained soils (ie.sand) and it has also been widely used in the ceramics industry. While some industries have a long history with sedimentation, it has also provided these industries with some problems.

For a start, the calculation of size from sedimentation rate is only valid for spherical particles.  If the particles are not spherical then the results reported can be very different from reality.  It is also necessary to know the density of a material.  If density is not known, or if a sample contains a mixture of materials, it is difficult to obtain accurate results. It is impossible to determine the size of emulsions particles, where the material does not settle. Similarly, it is difficult to get accuratete measure of large and very dense materials where the material quickly settles.

Electrozone Sensing:

This technique is particularly useful for measuring the size of blood cells but it poses some problems as a technique for measuring industrial materials. Samples must be suspended in a salt solution so it is not possible to measure emulsions and many dry powders.  Measuring the particle size within sprays simply cannot be done.

Laser Diffraction:

A popular and preferred measurement technique, laser diffraction also has the advantage of being one of the most accurate ways of measuring particle size. Other advantages of laser diffraction include:

  • It provides a great degree of flexibility for different materials
  • Results and answers can be provided quickly (in less than one minute)
  • It is an absolute method of particle analysis
  • There is no need to calibrate instruments against a standard
  • It is possible to measure dry powders, suspensions, emulsions, sprays and many other materials
  • The technique provides a wide and dynamic range of measurement
  • The measurement of an entire sample is possible
  • The technique can be repeated easily.

While there are a range of ways to measure and analyse particle size, the most appropriate way of measuring any given material will and should depend on the type of material that is being measured.

Looking for the perfect analytics instrument for YOUR next big discovery?

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Facts About Laser Diffraction

Particle Science - Guide,

As a technique of particle size analysis, laser diffraction is widely used and has many advantages. It offers a high level of precision, a fast speed of response, high potential for the repetition of results and a wide measurable particle diameter range. Particle size analysers offer a sophisticated way of measuring particle size and enable incredible insight and understanding of the particles that make up materials used in a range of industries.

Laser diffraction is an important technique for measuring particle size. Here we offer a range of facts about this technique:

  • It is also known as Low Angle Laser Light Scattering (LALLS).
  • Considered a standard method in many industries because of its ability to characterise particles and for reasons of quality control.
  • Huge advances have been made in instrumentation over at least the last two decades.
  • The method is founded on the fact that the angle of diffraction is inversely proportional to particle size.
  • The instrument consists of a laser (as a source of coherent intense light that has a fixed wavelength), a detector (typically an array of photo sensitive silicon diodes) and a means of passing the sample through a laser beam.

Laser diffraction is so popularly and extensively used because it offers a number of advantages. These advantages include:

An absolute method grounded in fundamental scientific principles – In this method it is not necessary for an instrument to be calibrated against a standard. However, validation of equipment is possible to prove that it is performing to a standard that can be traced.

Wide and dynamic range – In measuring particle size, good equipment will allow the user to measure particles sized between approximately 0.1 and 2000 microns.

Flexibility – Laser diffraction offers new possibilities for measuring materials. It is even possible to measure the paint that is sprayed from a nozzle in a paint booth. The pharmaceutical and agricultural industries are two of the many industries that have benefited greatly from such advances.

Dry powders – Even dry powders can be measured through the technique of laser diffraction. Although this may result in a poorer level of dispersion than if a liquid dispersing medium was used, it is an advance that dry powders can be directly measured. In combination with a suspension analysis, it can support the assessment of the amount of agglomerated material in a dry state.

Liquid suspensions and emulsions – It is possible to use a recirculating cell to measure liquid suspensions and emulsions. This technique promotes a high level of reproducibility and facilitates the use of dispersing agents and surfactants to determine the primary particle size. If it is possible to do so, it is preferable to take measurements in a liquid suspension.

Sample measured – This technique allows for the whole of the sample to be measured. As the sample passes through the laser beam, diffraction is measured for all particles.

Rapid – This technique is so rapid that results can be derived in one minute or less. Feedback can therefore quickly be provided to plants and repeat analyses can also be made quickly.

Repeatable – This technique is highly repeatable and knowing that the results can be relied upon provides peace of mind.

A sophisticated method for determining particle size, laser diffraction is widely used and offers distinct advantages that are beneficial for many industries.

Looking for the perfect analytics instrument for YOUR next big discovery?

Speak with the ATA Scientific team today to get expert advice on the right instruments for your research

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Particle Size Analysis Basics

Particle Science - Guide,

In many industries, the ability to determine the size of particles is not only useful but can be very important. A Laser diffraction particle size analyser is commonly used to provide this sort of information but the processes used to obtain particle size can be quite complex. Sampling, dispersion processes and the shape of materials all contribute to the complexity of particle size analysis.

Here we provide key information for understanding particle size analysis.

What does it mean to describe a particle?

When dealing with a three dimensional shape, one unique number cannot accurately be given to describe its size. While this remains true in so many situations and circumstances, it is particularly relevant when seeking to describe complex shapes such as a grain of sand or even a particle within a can of paint.

While many of us may question why this information is so important, it is imperative and influential for people such as Quality Assurance Managers within particular industries and organisations. For example, a Quality Assurance Manager may need to know whether the average size of particles has increased or decreased since the last production run.

The equivalent sphere

So often we seek to describe a shape by only one number. As has been mentioned, this is problematic as there is only one shape – a sphere – that can be accurately described by one number.

In order to arrive at a particular number to explain the size of a shape, equivalent sphere theory is frequently used. Using the equivalent sphere theory, some property of the particle is measured and it is then assumed that this refers to the diameter of a sphere to describe the particle. Essentially, this means that three or more numbers do not have to be used to describe a three dimensional particle. Although it is more accurate to describe three dimensional particles with three or more numbers, it is also inconvenient and can become unmanageable.

Using different techniques

When a particle is examined under a microscope, a two dimensional image is seen and the information that is deduced relates to the two dimensional shape. Consequently, there are a number of different diameters that can be reported. If the maximum length of the particle is used, then the result relates to a sphere with diameter of the maximum dimension. Conversely, if the minimum length is used for the calculation, then the result pertains to a sphere with diameter of the minimum dimension.

It is therefore important to note that each technique used to measure a particle will provide a unique result because it measures a different property of a particle.

In light of this, there is no absolute right or wrong answer. All answers are correct for the techniques that are used and the dimension of the particle that they are measuring.

What does this all mean?

For those to whom particle size analysis is important, different techniques for measuring particle size mean that there can be no standard size for particles such as grains of sand. If meaningful comparisons are to be made between different techniques, it must be done with standards containing spherical particles. Further to this, characterisation of particle size standards is only possible when the same technique has been used and this allows comparison between instruments that use the same technique.

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Laser Diffraction – Why is it Such an Important Particle Sizing Technique?

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As a technique of particle size analysis, laser diffraction offers the ability to learn more about particle size and shape with a high level of accuracy. This information is incredibly useful to industries and for research and the information generated is influential in streamlining and enhancing processes used.

Particle sizing technologies are intended to provide a reliable measurement (that can be reproduced) for different sized particles. There are multiple technologies for particle size analysis and it is vital to appreciate that no one piece of technology is appropriate for every job. There are advantages and also drawbacks to each piece of measurement technology and different devices are best suited to particular industries or tasks.

Why is measuring particle size and shape important?

Today, many industries rely on the ability to use a particle size analyser to measure the size of particles of varying sizes, including those that are incredibly fine. We know that for all materials that are milled or ground, the resulting particle size is typically the factor that determines performance of the product and efficiency of the process.

As a result, analysis of particle size has become crucial to industries such as the pharmaceutical, food and beverage, building and chemical industries.

Why is laser diffraction one of the most important and used particle size analysis techniques?

As it can be used to determine particle size of liquid suspensions, dry substances and aerosols, laser diffraction is most popular for its dynamic nature and range.

However, different particle size analysis technologies can quite often produce different results for the same sample. There is a logical reason for this, being that each particle analysis measurement technique measures a different part of aspect of the same material. For this reason, all particle size analysis results must be considered as the best indications possible rather than definitive and exact measurements.

Why is ‘Equivalent Sphere’ Theory used?

Even the smallest particles are multi-dimensional and it is very hard, not to mention problematic, to describe a multi-dimensional particle using one dimension only.

As only one shape, a sphere, can be described by one dimension, all techniques that measure particle size relate this to an ‘equivalent sphere’.

What are the most common particle sizing techniques used?

  • Sedimentation techniques
  • Sieve technique
  • Aerodynamic sizing technique
  • Laser diffraction
  • Image analysis technique

With so many techniques for measurement available, which should be used?

Ultimately, there is no simple and definitive answer to this question. Because different products and processes can be measured, the most suitable measurement technology for the product and process needs to be chosen and applied. Having said this, of all of the technologies, the one that can be used most widely is laser diffraction.

The advantage of laser diffraction as a tool for determining particle size and shape is that it can be used to gain information about a wide range of particle sizes and sample types. This technique is suitable for materials such as sprays, powders, suspensions and emulsions and results are able to be delivered in the form of a ‘volume’ distribution, which is the most significant and logical description when bulk material properties are being analysed.

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Seven Facts About Laser Diffraction

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Laser diffraction is one type of particle size analysis and is a technique known and respected across many applications for its ability to provide fast and reliable particle size data. In this type of particle size analysis, a cloud (or ‘ensemble’) of particles that is representative of the greater collection, travels through a broadened beam of laser light which scatters the light on to a specialised lens. Information about particle size and shape can then be deduced from the scattered pattern of light.

The laser diffraction technique assumes that the particles that pass through a laser beam will scatter light at an angle that directly corresponds with their size. It then follows that as the size of particles decreases, the scattering angle that is observed will increase. Essentially, light scattered at narrow angles with high intensity indicates large particles and particles scattered at wider angles and with low intensity suggest smaller particles.

A laser diffraction system requires the following:

  • A laser – this is necessary as a source of intense and coherent light that is of a defined wavelength
  • A sample presentation system – this ensures that the material being tested successfully travels through the laser beam as a stream of particles that have a known state of dispersion that can be reproduced
  • Detectors – specialised detectors are applied to measure the light pattern produced across a range of angles.

Facts About Laser Diffraction:

  1. Over the last twenty years, laser diffraction has, to a large extent, replaced traditional methods of particle size analysis, such as sieving and sedimentation.
  2. Laser diffraction has replaced microscopy (including optical and electron) for particles that are larger than tens of nanometres.
  3. Laser diffraction offers many advantages, including: efficient and fast operation and ease of use; the capacity to reproduce results; a vast size range that spans up to five orders of magnitude.
  4. Laser diffraction analysers do not only measure simple diffraction effects. Light sources that do not make use of lasers are sometimes used to enhance the primary laser source to reveal extra information about particle size and shape.
  5. Particles that relate to or are measured for particular industries commonly resemble spheres and corners and edges of these particles are generally smoothed as a result of the rolling and turning motion originating from sample circulation as particle size and shape is measured.
  6. While modern equipment can give quite precise results, it can never be assumed that the size of particles (produced through laser diffraction or any other type of particle sizing measurement) will not differ from their true dimension.
  7. The spherical modelling theory remains the only accepted and logical choice used in a commercial device intended to analyse a wide range of samples, regardless of the real particle shape and size.

Laser diffraction is a particle size analysis technique that generates results that are incredibly useful for processes used for research and in various industries. Providing details about particle size and shape, this technology can be used to provide fast and accurate results.

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