Tag Archives: Particle Size Analyser

5 Reasons to Combine Laser Diffraction Particle Sizing and Image Analysis

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Particle size is by far one of the most important physical properties of particulate samples. The measurement of particle size distribution is routinely carried out across a wide range of industries for mainly two reasons; to better understand how particle size will affect their product performance and to optimise and control the quality of products and processes during manufacturing.

In addition to particle size, the shape or morphological surface properties of the particles can be equally as important or even interrelated eg. surface area and particle size. The size and shape of a particle can influence a variety of material properties. From dissolution rates of tablets, stability of paints, the texture of foods and coatings, to the flowability and packing density of powders, understanding particle size and shape can be critical when designing a product for a particular purpose or behaviour.

Why measure particle size using laser diffraction?

Laser diffraction technology for routine particle size analysis remains the method of choice across a diverse range of industrial sectors.  The speed and ease of use of this technology and the wide dynamic range (nm to mm)1 give users access to quick, reliable particle size data with minimal effort. 

Laser diffraction is a non-destructive ensemble technique, meaning it calculates particle size distribution for the whole sample rather than building up a size distribution from measurements of individual particles. A sample, dispersed either in solution or fed dry which is passed through a collimated laser beam, scatters light over a range of angles. Large particles generate a high scattering intensity at relatively narrow angles to the incident beam, while smaller particles produce a lower intensity signal but at much wider angles. Laser diffraction analysers like the Mastersizer 3000 record the angular dependence of the intensity of light scattered by a sample, using an array of detectors. The range of angles over which measurements are made directly relates to the particle size range which can be determined in a single measurement2. 

However, particles are 3-dimensional objects, and unless they are perfect spheres (e.g. emulsions or bubbles), they cannot be fully described by a single dimension such as a radius or diameter3. Therefore, to simplify the measurement process particle size is defined using the concept of equivalent spheres. The equivalent sphere concept works very well for regular-shaped particles, but for particles that are shaped like needles or plates, the size in at least one dimension can differ significantly from that of the other dimensions.

For this reason, many groups also employ low-cost sieve analysis to evaluate the large particle content. However, in addition to being slow and manually intensive, sieving lacks sensitivity at the fine fraction of the distribution, particularly at < 38 µm which is known as the sub-sieve size region4. Excessive fines in this size range tend to cause attraction or bridging of particles and are often combined with humidity or sticking issues. Wet sieving may help, but screen blocking is still common especially in smaller sizes.  Laser diffraction using wet or dry dispersion methods overcomes these issues and enables faster, simpler analysis with better resolution and control of agglomerates. 

How can imaging help measure particle size more accurately?

Imaging allows users to visually see the particles to determine particle size and shape and is complementary to laser diffraction particle sizing, allowing more data to be collected and measured. 

The Hydro Insight is a dynamic imaging tool that sits alongside the Mastersizer 3000 particle size analyser. It provides real-time images of individual particles as well as quantitative data on particle shape at the same time as laser diffraction size measurements. Particles dispersed by the Mastersizer 3000’s wet accessories flow through the Hydro Insight and are then photographed by a high-resolution digital camera at up to 127 frames per second. The camera takes images of the suspended particles in the analysis cell, converts them to a digital format, and sends the information to the software for final analysis in real-time. Individual particle images are viewed directly and captured as image files for post-run processing. More than 30 size and shape metrics available such as circularity, ellipticity, opacity, mean diameter, and aspect ratio allows the user to understand how the combination of particle size and shape affects material behaviour. 

Adding the Hydro Insight to your Mastersizer 3000, combines shape data with size data to enable the following benefits:  

#1 Gain a deeper understanding of why materials behave the way they do 

Hydro Insight provides real-time images of liquid dispersions of individual particles to provide quantitative data on particle shape. Circularity and aspect ratio (width and length) can be used to distinguish between particles that have regular symmetry, such as spheres or cubes, and particles with different dimensions along one axis, such as needle shapes. Other shape parameters that can be used to characterise particle form include elongation and roundness. This plays a significant role in applications such as powder processes where size and shape can influence powder flowability/ blending properties, cohesion/ formation of agglomerates, tableting/ compaction behaviour, porosity/ reactivity, and even health and safety. When assessing pharmaceutical drug products the size and shape of particles can influence drug delivery within the body, dissolution behaviour, bioavailability, and drug efficacy. 

#2 Speed up method development

When setting up a method to measure particle size using laser diffraction, achieving optimal dispersion is important to prevent agglomerates and to ensure the reproducibility of results. This can involve multiple steps from varying the dispersant type or amount of surfactant to the amount of mechanical mixing or ultrasound needed. By combining size analysis with imaging, particles can be seen live in a liquid and any agglomerates that form can quickly be identified and dispersed using optimal conditions. Users can see their dispersion as they develop laser diffraction methods, saving time for other projects.

#3 Build confidence in product quality

Laser diffraction is an ensemble technique able to measure particle size and particle size distribution for a wide range of samples over a wide dynamic range. However, for materials that require narrow polydispersity, the presence of just a few large or outlying particles can make a big difference to their performance. Large particles can block printing nozzles or cause imperfections in coatings or even be a source of immunogenicity when developing pharmaceutical drugs. Adding the Hydro Insight to the Mastersizer 3000 provides images of individual particles and gives a number-based particle size distribution, so it becomes sensitive to even small numbers of oversized particles leading to enhanced resolution. 

#4 Quickly troubleshoot

Laser diffraction offers a simple, fast, and reproducible technique to measure particle size reliably; however, samples can sometimes present results that are unexpected, contain artifacts or simply be “out of spec”. Looking at your material on a microscope often needs a different sample preparation method and that can make the picture more complicated. 

By adding imaging to laser diffraction workflows, the process of troubleshooting can be automated and therefore speed up analytical processes. With Hydro Insight, any anomalies in results can be assessed to determine whether they were caused by oversized particles, agglomerates, bubbles, or something else.

#5 Faster method transfer

Sieving is one of the oldest and simplest techniques for separating particles based on their size. However, the time it takes to obtain accurate results, the poor resolution, and problems associated with particle agglomeration and sieve blockage, have seen sieving being replaced in most industries with laser diffraction. Laser diffraction and sieving can provide similar results when characterising spherical or semi-spherical particles, however, differences can be observed for non-spherical particles because each technique measures different particle properties. Laser diffraction measures light scattering from a group of particles and reports size as a volume distribution of spheres that would produce the recorded pattern. In comparison to sieving, a mixture of size, shape, and density generates a weight distribution. Therefore using sieving, an elongated particle will be reported using the smaller dimension and will appear smaller when compared to laser diffraction results.  

The Hydro Insight provides a window or a set of eyes into the Mastersizer. It records thumbnail images of a dispersion of particles and measures quantitative particle shape data. It can report different size parameters for irregular particles such as particle width and elongation data that may correlate better with sieve analysis and thus simplify the transfer process from sieves to laser diffraction.  

Laser diffraction provides fast, reproducible particle size data for a range of applications. Image analysis is often used in combination with laser diffraction to provide a further understanding of how materials behave as well as being an orthogonal technique that helps with method validation.

So why choose the MASTERSIZER 3000 with the Hydro Insight?

The MALVERN MASTERSIZER 3000 system has a unique, compact design that uses laser diffraction to measure particle size distribution. The Hydro Insight sits alongside the Mastersizer 3000 and provides real-time images of particles, as well as quantitative particle shape data. This enables users to gain a deeper understanding of their products for easier troubleshooting and quicker method development.  Learn more about the Malvern Mastersizer 3000 and Hydro Insight system, speak to ATA Scientific today.

Particle Size Analysers and Their Industry Uses

Particle Science - Guide,

For many industries, the ability to determine and analyse the average size of particles in a sample is important and informative. As a result, particle size analysers have a significant role to play. Able to very quickly and efficiently measure the size of grains or particles in a sample, this equipment provides data that is useful to companies and industries alike. Not only can the size of grains or particles be indicated, information about particle shape and formation can also be deduced.

What is a Particle Size Analyser?

A particle size analyser is a specialised piece of equipment that is used to measure the sizes of grains and particles that make up a particular sample. Capable of quickly measuring the sizes of many particles in a sample, particle size analysers can simultaneously provide information about particle size distributions. This information is useful and significant in many industries.

Where does Particle Size Analysis occur?

Particle size analysis is a branch of Particle Science. Analysis of particle size and shape usually takes place in specialised particle technology laboratories.

Why and how is Particle Size Analysis useful in industry?

In many industries, it is important for particle size and shape to be known and understood. These industries include: the chemical, mining, forestry, agriculture and aggregate industries.

Chemical Industry

Knowledge about particle size is useful in the chemical industry as wet and/or dry materials can range in size from nanometres to centimetres and a huge number of sub-industries are affected. Also, in the chemical industry it is widely understood that different methods of particle size analysis can produce different results depending on the method used to determine its measurement. In light of this, it is very important that the method most relevant to its use is used to determine a particle’s size.

Mining Industry

Mining operations involve the processing of particular materials. It is important to have intelligence about particle size and shape as the use of over-sized materials through processing channels is likely to damage equipment and decrease the rate at which production processes operate. Knowing the size of materials means that the appropriate equipment is used and systems can operate with optimum efficiency. When crushing materials, particle size analysis helps to ensure the effectiveness of Semi-Autogenous Grinding Mills.

Agriculture Industry

In agriculture, contamination of products can occur if unwanted materials are not identified. The use of a particle size analyser allows companies to monitor processes and ensure that unwanted materials are detected and isolated.

Forestry Industry

Particle size analysis of wood products is used to ensure that high quality standards are upheld in the forestry industry and that the products produced are of excellent quality. In this context, particle size analysis assists companies to reduce waste and increase productivity.

Aggregate Industry

The use of particle size analysis supports aggregate companies to create robust, durable and long-lasting roads, as well as other products.

An asset in your industry

Particle size analysis is incredibly useful for determining the size and shape of particles. Without this information, the processes used in a number of industries would be inhibited or drastically slowed.

The equipment used to indicate particle size and shape is sophisticated enough to provide this information quickly and accurately, making it an important asset for companies and industries more generally. ATA Scientific offers a range of particle size analysers, so contact us today to find the right one for you.

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Different Methods of Particle Size Measurement

Particle Science - Guide,

Particle size analysis can seem a complex and intricate area. The thought of attempting to measure and draw conclusions about microscopically small particles can seem incredibly confusing and the techniques used to measure particles can perhaps seem daunting. Particle size analysers are of great use in achieving such measurements and techniques such as laser diffraction assist us to understand more about the properties of materials.

However, in order to understand some of the higher level concepts related to this area, it is necessary to have a sound grasp of the concepts that inform results.

Mean, median and mode

These three terms are too often confused and thought to mean the same thing. Far from being one and the same, these terms require definition:

Mean – Mean relates to the arithmetic average of the data.

Median – When concerned with particles, median is the value of the particle size that precisely divides the population into two halves. This means that there is 50% of the population above and 50% of the population below the value.

Mode – Mode defines the most common value in a frequency distribution. This also corresponds to the highest point of the frequency curve.

Common methods of particle size measurement

Because different dimensions of the particle are measured when different techniques are used, different results are obtained. Of the different methods of measurement, each has its own advantages and disadvantages.

Sieves

While this is an old technique, it has the advantage of being cheap and particularly useful for the measurement of large particles. In industries such as mining, this can be particularly useful.

The main disadvantages associated with this technique include: it is not possible to measure sprays or emulsions and measurement of dry powders is also difficult when particles become small. Wet sieving can help to overcome this problem, but it is then very difficult to reproduce results. Materials such as clay, which are cohesive and agglomerated, are also difficult to measure.

As particles tend to orientate themselves through the sieve, operating methods and measurement times need to be standardised if accurate and meaningful results are to be obtained.

Sedimentation

This has been a common method used (historically) in clay and ceramics industries.

There are two main problems with this process: the density of the material is needed and so it is not useful for determining particle size of emulsions where the material does not settle or for dense materials where the material settles quickly. Samples containing components of mixed density can not be accurately resolved. Measurement of small particles is very slow and therefore the process of repeating testing can be tedious.

Electrozone testing

This technique is very good for measuring red blood cells, but for real, industrial materials there are quite a few problems. It is very difficult to measure emulsions and dry powders and it is impossible to measure sprays. It is necessary to measure in an electrolyte and the required calibration standards are expensive.

Laser Diffraction

This is an often favoured technique that is considered to be one of the most accurate and reliable. It has a number of important advantages:

  • It is very flexible and can measure all types of particles (powders, emulsions, suspensions and sprays)
  • It is very rapid (answers can be produced in less than sixty seconds)
  • It offers an absolute method of particle analysis that is grounded in scientific principles and makes it possible for measurements to be taken without the need to calibrate any instrument against the standard
  • The technique provides a very wide and dynamic range
  • It is possible to measure an entire sample
  • The technique is highly repeatable.

Combine technique with instrument

The technique used to measure particle size will depend on the material being analysed, and the instrument used should be one of the highest quality. ATA Scientific is a trusted brand selling a range of scientific instruments suited to measuring particle size. Contact us today to find the right instrument for you.

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Using Laser Diffraction for Semisolid Formulations

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Because they provide a solution to issues of bioavailability often seen in new drug candidates, semisolid drug formulations are becoming more and more common. These days, they make up a significant proportion of pharmaceutical dosage. When it comes to semisolid drug production, particle size is an undeniably crucial parameter. For this reason, finding an appropriate particle size analyser is of the utmost importance.

In this article, we’ll look at laser diffraction, a widely used method of particle size analysis that can be used for semisolid formulations at elevated temperature.

Why semisolids?

Something like 40 per cent of new chemical entities are challenging to modern drug delivery systems because of their poor aqueous solubility and low bioavailability. Semisolid formulations offer an answer to this problem. Additionally, patient compliance is improved, as semisolid products can be delivered painlessly and with minimal side effects.

Some examples of semisolid drugs include topical creams used for localised skin layer action (eg. Antiseptics and anaesthetics); as well as transdermal drugs that enter the body percutaneously. Semisolids have gained particular traction in transdermal delivery thanks to advances in delivery technology, such as slow release patches. When a transdermal patch is applied to the skin, the drug will enter the blood either through sweat ducts, hair follicles or the stratum corneum (the outer layer of the epidermis). However, the potential of the transdermal drugs to deliver the active ingredient is reliant on the semisolid’s rheological properties.

What makes a good semisolid?

The efficacy and safety of semisolid compounds are largely down to particle size and size distribution. These can have profound effects on bioavailability, dose uniformity and more. The relationship between product performance and particle size can be examined with data generated from the laser diffraction method of particle size analysis, which rests on the idea that particles that move through a laser beam will scatter light at an angle proportional to their size.

By applying stringent techniques in designing its particle size, the local efficacy of a drug’s entry can be maximised, and adverse reactions can be prevented. However, if settling or sedimentation occurs, efficacy will often be compromised due to irregular delivery.

Some of the methods of particle size analysis that have been used over the years include X-ray tomography, confocal imaging and scanning electron microscopy. However, these can usually only be applied while the product is being developed, and usually only with a small amount of material, which can cause problems when trying to characterise larger samples.

Laser diffraction: Why it’s the way forward

Laser diffraction, on the other hand, allows for very rapid measurement, accurate analysis, a broader measurement range, and the capability of looking at many sample types. One of its best properties is its sensitivity to changes in coarse particle fraction which makes it great for studying the instability that results from sedimentation or agglomeration. Additionally, the latest laser diffraction systems are completely automated and user-friendly.

One of the problems with using laser diffraction for semi-solids, however, is that samples are not liquid at room temperature. To deal with this, the laser diffraction system can be equipped with a dispersion cell and water bath, elevating the temperature to make more detailed particle size measurements.

Find the right particle size analyser

It’s important that you not only use the best method for analysing semisolid formulations at elevated temperature, but also use the best instrument. ATS Scientific is a trusted brand that offers a range of quality particle size analysers. Contact us today for more information.

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Understanding and Choosing a Particle Size Analyser

Particle Science - Guide,

Research today would not be so advanced and precise were it not for the existence of Particle Size Analysers. Without these pieces of equipment, much research would be incredibly different to carry out and benefits realised through science may not be known.

What are the Benefits of Particle Size Analysers?

There are a range of benefits from using a Particle Size Analyser, including:

  • Accurate and effective results are delivered in the form of readouts.
  • In a particular sample, particle size analysers identify the size and allocation of particles.
  • The size and shape of particles can be determined from various states of matter – this enables laboratories to examine and analyse many different types of samples and means that research is not limited or likely to omit important features.

Important things to know about Particle Size Analysers

There are a few key things to know about Particle Sizer Analysers that you may not already be aware of, including:

  • Not all Particle Size Analysers are the same. As different pieces of equipment are developed in different ways, some pieces will be better suited for particular purposes and use in different contexts. For example, particular models will be best suited to analysis of specific materials and samples.
  • Different models of Particle Size Analysers are likely to produce different results. This is influenced by whether the device being used is appropriate for analysis of the sample being studied. It is necessary to match devices with samples.
  • As a result of integrity within the industry, significantly flawed and problematic models are not generally available. Having said this, machinery is always subject to malfunction and occasionally devices may have defects. Sometimes, transportation of devices can cause some damage. To counter this, it is important and good practice to carefully inspect all models when they are delivered.

Deciding on a Particle Size Analyser

Because Particle Size Analysers are such a vital piece of equipment for any laboratory and necessary for determining the size and shape of particles, the decision of which one to choose to best meet needs should not be made lightly.

Modern and best quality Particle Size Analysers can today include features such as a short optical bench and intuitive software. Added to this, some devices are capable of analysing both wet and dry materials. An automated microscope and high resolution camera are also features of some state of the art devices. In best quality systems, these features are streamlined and integrated to form an imaging workstation.

Particle Size Analysers are highly specialised pieces of equipment that fulfil an important need; they are unique and so respected for their capacity to determine particle size and shape. Versatile and able to be used to enhance practice and processes in a variety of industries, Particle Size Analysers assist companies to avoid costly errors, damage to machinery and reduced productivity. When companies and industries have greater intelligence about the materials being used, the most effective methods of working can be applied.

Of course, companies should consider such an important investment carefully. Time and research should be prioritised to ensure that a Particle Size Analyser is chosen to best meet the needs of the business. Advances made in research today illuminate the benefits of these devices and the potential they have for enhancing processes and ultimately, the quality of final products.

Choose ATA Scientific

ATA Scientific is a trusted supplier of scientific instruments, offering a range of instruments suited to your needs. Browse our product range today to find the right Particle Size Analyser.

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Using Dynamic Imaging Particle Analysis to Characterise Biologics

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In recent years we have seen an increase in the role of biologics in medicine. Biologics are medicinal products that are created by biologic processes instead of chemical synthesis; these include products such as blood, vaccines, gene therapy, allergenics or somatic cells. Because of the increased role of biologics, the need to characterise particulate matter within those biologics has increased as well. In this article, we’ll take a look at how dynamic imaging particle size analysis is being used to characterise particulates in biologics, as well as some of the factors that need to be considered when using the technology.

The early days: Light Obscuration

In the early days of particle analysis in biologics, analysts used light obscuration techniques to attempt characterisation, but this method meant they faced a few hurdles. These were as follows:

The transparency of aggregated proteins

Biologics are subject to protein aggregation — that is, the formation of larger particles from a combination of smaller ones. Because aggregated proteins are transparent or “soft”, they are much tougher to detect than opaque particles, and light obscuration technology was not always able to detect them.

The amorphousness of aggregated proteins

The shape of the aggregates vary from circular to strand-like shapes. Light obscuration devices are capable of measuring size, but they assume that the particles are spherical in shape. Because aggregates could be absolutely any shape, many measurements were inaccurate.

The biologics are delivered through pre-filled syringes

This could result in silicone droplets being present, and might also result in inflated particle counts.

The introduction of Dynamic Imaging

A dynamic imaging particle size analyser, on the other hand, is capable of making various measurements even if the particle is transparent. It works by capturing digital microscopic images of biologic particles as they make their way through a flow cell. The result is a more detailed description of the particle and its shape, which also allows for analysts to recognise the difference between aggregates and silicone droplets.

Dynamic Imaging limitations

It would seem, then, that dynamic imaging has solved the problem of characterising biologics — but that’s not to say that the technology is perfect. In particular, there are three factors that analysts must consider whenever characterising biologics with the use of dynamic imaging. These are:

Resolution

Digital images don’t show the real world in the same way that the human eye does. Instead, images are pixelated, which means dynamic imaging systems can only count particles that are no smaller than 1µm, and can only differentiate shape for particles larger than 2-3µm. Electron microscopy is needed to measure particles smaller than these limits, but such a technique has many shortcomings of its own.

Colour threshold

Images are not only limited in size; they are also limited in their colour scale. Because imaging systems are backlit, particles in the optical path reduce the light that passes through to the camera sensor and, as such, the incoming pixel intensity becomes darker. This works fine for opaque particles, but not so well for the transparent protein aggregates. Additionally, the amorphous nature of the aggregates causes light to bend awkwardly around the structure, creating further confusion.

Image quality and sharpness

This great effects on the precision of particle measurements. The less sharp the image, the lower the accuracy when attempting biologic characterisation.

Finding a particle size analyser

Particle size analysers play a key role in biologics, so it’s important that you one you use is of a high quality and from a trusted supplier. ATA Scientific offers a range of quality particle size analysers perfect for characterising particulates in biologics. Contact us today for more information.

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10 Benefits of Real-Time Particle Size Analysis

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If you’re looking for optimal performance in the particle size analysis process, then real-time or ‘on-line’ particle size analysis methods, such as laser diffraction, are the way to go. There are several applications for real-time particle size analysis, including sticky-wet concentrated slurries, liquid emulsions, and dry particulate streams. With the use of automated on-line analysis, the frequency of measurement increases significantly, enabling a reliable and efficient data stream to be delivered.

Benefits of real-time particle size analysis

There are several benefits that can occur as a result of utilising real-time particle size analysers, outline below.

1. Increased return of investment (ROI)

These online instruments have been shown to be extremely sturdy and capable of providing 24/7 operation with only a small amount of upkeep. You can achieve visible ROI within six to 12 months of operation, with both product quality and plant capacity enhanced by automatic real-time measurement.

2. Lower energy

While milling operations are generally quite energy-intensive, consumption has been shown to see an exponential increase as particle size becomes smaller. Quality control failure can occur as a result of under-milling, while over-grinding can result in too much energy being used. With real-time particle size analysis you will see minimal energy use to create products that meet specifications.

3. Real-time control

From metal powders to pharmaceuticals, particle size is a key performance parameter in a lot of particulate products. Real time particle size analysis, therefore, makes a lot of sense. The on-line systems are capable of measuring up to four particle size distributions per second.

4. Troubleshooting

By utilising continuous measurement, you’ll be able to see the outcome of every variable in real time, which makes troubleshooting a lot easier than viewing these variables with the disadvantage of occasional off-line analysis methods.

5. Increased efficiency

Using off-line analysis to examine process parameters and their effects can be time consuming. With real-time particle size analysis, you’ll be able to evaluate these situations in minutes instead of hours. Causal links become clear at a much quicker rate than normal.

6. More intelligent process development

Since the acquisition of knowledge is the main role of process development, real-time measurement has obvious advantages. Potential problems can be detected at an early stage, speeding up the knowledge gathering process.

7. Quicker product changeover

Since, during changeover, you’ll want to get to the set point as fast as the plant dynamics will allow, on-line systems are definitely the way forward. Waiting on lab results to ascertain whether or not it’s safe to switch to the in-spec collection silo is no longer necessary; instead, you’re fed this information in real time.

8. Immediate upset detection

In general, offline analysis is done on an hourly basis (at most). As a result, any upsets may not be detected for an hour at best and response to upsets may take even longer – enough time to spoil a batch. On-line analysis allows upsets to be detected immediately.

9. Higher sensitivity to quality

Real-time data is sensitive to changing conditions, allowing for tighter process control. Off-line data, on the other hand, is usually an average taken from composite samples, which lacks the sensitivity necessary to spot out-of-spec samples.

10. Reduced operator risk

Occupational health and safety problems can arise during the sample extraction process, especially when materials are highly toxic or volatile. The use of a real-time particle size analyser eliminates this risk.

Find the right product to get the benefits

ATA Scientific offers scientific instruments suited to many scientific endeavours, including real-time particle size analysers. Browse our range of particle science products today to find what you need.

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Factors Affecting Reaction Rate in Chemical Kinetics

Particle Science - Guide,

Chemical kinetics or reaction kinetics is the study of rates of chemical processes. The study of chemical kinetics includes investigations on how different experimental conditions can influence the speed of chemical reactions and produce information about the reaction’s mechanism and transition states. It also includes the construction of mathematical models that can describe the characteristics of a chemical reaction.

Factors affecting reaction rate

Chemical kinetics deals with the experimental determination of reaction rates from which rate laws and rate constants are derived. In order for a reaction to occur, a collision must take place. This collision has to be of proper orientation and have sufficient energy to break the necessary bonds.

There are several factors that influence the rates of chemical reactions. For instance, the particle size distribution of a material, which can be deduced using a particle size analyser, will affect the reactivity of solids participating in chemical reactions. The following are other factors:

Nature of reactants

Reaction rate variation is dependant on which substances are reacting. Fast reactions include acid reactions, the formation of salts and ion exchange. Reactions tend to be slow when covalent bond formation takes place between the molecules and when large molecules are formed.

Physical state

The physical state, i.e. solid, liquid or gas, of a reactant is also an important factor of the rate of change. When reactants are in the same phase, thermal motion brings them into contact. If they are in different phases, the reaction is limited to the interface between reactants and reactions can only occur at their area of contact. Vigorous shaking and stirring may be needed to complete the reaction.

Concentration

According to the collision theory of chemical reactions, concentration is an important factor because molecules must collide in order to react with each other. When the concentration of the reactants increases, the frequency of the molecules colliding increases, striking each other more frequently. Increasing the amount of one of more reactants causes the collusions to happen more often, increasing the rate of reaction.

Temperature

Molecules at a higher temperature have more thermal energy and collision frequency is greater at higher temperatures.

Catalysts

Catalysts are substances used to facilitate reactions but remain chemically unchanged afterwards. The rate of reaction is increased when the catalyst provides a different reaction mechanism to occur with lower activation energy.

Pressure

When the pressure is increased in a gaseous reaction, the number of collisions between reactants will also rise, increasing the rate of reaction.

Instruments that can be used for studying reaction rate

Stopped-flow

A stopped-flow instrument is a mixing device that is most frequently used to study rapid kinetics. Small volumes of solution are rapidly driven from syringes into a high efficiency mixer to initiate a fast reaction. These reactions are usually recorded by spectroscopic techniques such as UV absorbance, fluorescence or circular dichroism. The most commonly used detection method is fluorescence spectroscopy because of its high sensitivity.

Stopped flow instruments can be equipped with up to four syringes, one for the sample and two or three syringes for double or sequential mixing of reagents.

Rapid kinetics fluorescence

This is another instrument designed specifically for the detection of rapid kinetics. Combined with the Bio-Logic stopped-flow quenched-flow equipment, it makes a very powerful kinetics analysis system, one with high sensitivity and very efficient data acquisition. The Spectrometer can be configured to measure reactions by UV absorbance plus fluorescence or two different fluorescence wavelengths.

Find the best instrument

ATA Scientific offers a range of products that can assist you with your scientific endeavours, large or small. For information and advice on which product will suit your specific needs, contact ATA Scientific today.

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Uncovering the Relationship Between Genes and Proteins

Biomolecular Science - Guide,

What are Genes?

A gene is a basic unit of heredity in a living organism that normally resides in long strands of DNA called chromosomes. Genes are coded instructions that decide what the organism is like, how it behaves in its environment and how it survives. They hold the information to build and maintain an organism’s cells and pass genetic traits to offspring. A gene consists of a long combination of four different nucleotide bases namely adenine, cytosine, guanine and thymine. All living things depend on genes as they specify all proteins and functional RNA chains.

What are Proteins?

Proteins are large, complex molecules that play many critical roles in the body. They are necessary for building the structural components of the human body, such as muscles and organs. Proteins also determine how the organism looks, how well its body metabolises food or fights infection and sometimes even how it behaves. Proteins are chains of chemical building blocks called amino acids. A protein may contain a few amino acids or it could have several thousands. The size of a protein is an important physical characteristic that provides useful information including changes in conformation, aggregation state and denaturation. Protein scientists often use particle size analysers in their studies to discuss protein size or molecular weight.

Archibald Garrod

Archibald Garrod was one of the first scientists to propose that genes controlled the function of proteins. In 1902, he published his observations regarding patients whose urine turned black. This condition known as alkaptonuria happens when there is a buildup of the chemical homogentisate, which causes the darkening of urine. In most situations, excess amounts of amino acid phenylalanine are metabolised by the body. This led Garrod to surmise that the enzyme responsible for its breakdown must be defective in these patients. In addition, since the black urine phenotype was passed from generation to generation in a regular pattern, Garrod reasoned that a gene had to be responsible for the production of the defective enzyme. He attributed a defective enzyme to a defective gene, suggesting a direct link between genes and proteins.

The Relationship Between Genes and Proteins

Most genes contain the information require to make proteins. The journey from gene to protein is one that is complex and controlled within each cell and it consists of two major steps – transcription and translation. Together, these two steps are known as gene expression.

Transcription: Information stored in a gene’s DNA is transferred to a similar molecule called RNA in the cell nucleus. Although both DNA and RNA are made up of a chain of nucleotide bases, they have slightly different chemical properties. The type of RNA that contains the information needed to make protein is called a messenger RNA or mRNA and it carries the message from the DNA out of the nucleus into the cytoplasm.

Translation: This is the second step in the production of proteins and it takes place in the cytoplasm. The mRNA interacts with a specialised complex known as a ribosome that reads the sequence of the mRNA bases. Each sequence has three bases called a codon, which codes for one particular amino acid. A transfer RNA or tRNA assembles the protein, one amino acid at a time. This continues until the ribosome meets a “stop” codon. The characterisation of different proteins can be conducted by Size Exclusion Chromatography as this technique can be used characterise molecular weight, structure and aggregation state.

Learn more about genes and proteins

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4 Benefits of On-Line Particle Analysis for Mineral Processing

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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.