Particle sizing techniques have advanced significantly throughout the past several decades. One of the most important contributions to this field is the application of laser-based technologies, complemented with the use of modern photo-detectors and digital computers. For some time, progress in laser light scattering technology has led to faster analyses, but the quality of the measurement was limited, often due to inadequacies in the detector.

Recognizing this need for better detection capability, Micromeritics developed the Saturn DigiSizer, an instrument that employed a laser diode and modern charge-coupled device (CCD) detector to significantly improve the sensitivity, resolution, reproducibility, and repeatability of the laser light scattering particle sizing technique.

With the Saturn DigiSizer II, Micromeritics has again improved this particle size technique. Utilizing a state-of-the-art CCD detector containing over three million detector elements, Mie theory, and unique design and data reduction features, the Saturn DigiSizer II gives users an extremely high level of resolution and sensitivity not available in other laser particle sizing systems. The level of detail, accuracy, and resolution enables the extraction of all available information from the static light scattering pattern. Users can now measure the same material on multiple instruments located at different locations around the world and get the same, highly detailed size distribution measurement on each instrument. The Saturn DigiSizer II is fully automated and requires little operator intervention.

Advantages

Applications

Ceramics

Particle Size information helps to determine curing and bonding procedures, control pore structure, ensure adequate green body strength, and produce a final product of desired strength, texture, appearance, and density.

Paints and Coatings

The particle size distribution of the pigment or filler influences the porosity, gloss, texture, color, color saturation, brightness, solids content, and film adhesion properties. The resulting porosity can control application properties such as fluidity, drying or setting time, and film thickness.

Cosmetics

The appearance, application, and packaging of cosmetics are influenced by the particle size distribution of the base powders, such as talc, and the pigments used in coloring.

Abrasives

Performance of abrasives, either in powder form or after being attached to a backing, is dictated by the size distribution of the abrasive powder. Over-sized particles lead to scratching and gouging. Undersized particles may lead to clogging of the abrasive papers.

Catalysts

Flow properties of fluid-cracking catalysts depend upon the particle size distribution of the particles. Surface area and pore structure of acid catalysts and catalyst supports result from the particle size distribution of the particles that are used to produce them

Mining

Refining efficiency of materials is related strongly to the particle size distribution of the raw mineral. For products that are used without chemical change, the size of particles taken from the mine may be too large for final usage. Analyses performed on the extracted minerals will help determine the amount of size reduction needed once the product reaches the processing plant.

Saturn II DigiSizer Configurations

The Saturn DigiSizer II System

Includes many options that allow you to tailor your instrument according to your specific needs. Multiple sample dispersion system options, an automatic autosampler, and a device for removing dissolved gases from the suspension liquid are available and contribute to the versatility of the system. These options are all designed and manufactured with the same care and attention to detail that produced the Saturn DigiSizer.

Liquid Sample Handling Units

The Saturn DigiSizer II’s sample handling unit ensures that every sample will be correctly dispersed. Micromeritics’ patented, state-of-the-art liquid sample handling units (LSHU) work with the instrument software to assure that sample suspension is of the proper concentration. A continuous flow through the reservoir provides a mixing action sufficient to keep all sample material suspended and prevents the settling of particles.

The LSHU has several automated features such as a built-in ultrasonic probe, automatic liquid level control, particle concentration detection, and a sample circulation system that continuously maintains dispersion. Auto-dispersion and auto-dilution features monitor the sample’s concentration and add liquid as needed until optimum concentration is obtained.

To reduce the possibility of sample carryover between analyses, the LSHU has a patented reservoir rinse design. While other designs simply fill and empty the reservoir to rinse, the Saturn DigiSizer’s LSHU has a feature that sprays the reservoir walls as the fluid level recedes. This removes residue that otherwise might cling to the surface.

Standard Liquid Sample Handling Unit

The standard unit includes a reservoir that is adjustable between 590 to 690 mL of dispersed sample with a circulation pump rate of 5 – 19 L per minute. It can circulate particles from 0.04 to 2500 µm. The high flow rate better supports particles that have an inherently higher settling velocity. In addition, the higher system clearance helps to avoid attrition of the particles during circulation.

Applications:

• Coarse particles
• High-density particles
• Quantity of sample, liquid supply and/or waste disposal is not a problem

Low-Volume Liquid Sample Handling Unit

The low-volume unit includes a reservoir that is adjustable between 100 to 120 mL of dispersed sample with a circulation pump rate of 2 – 12 L per minute. It can circulate particles from 0.04 to 750 µm in diameter. The low-volume liquid sample handling unit reduces cost by using smaller amounts of sample, and reduces the expense of waste disposal.

Applications:

• Sample quantity is limited
• Supply of dispersion liquid is limited and/or expensive
• Dispersion liquid may be hazardous to use and/or make disposal difficult

Particle Size Sample Preparation Accessories:

MasterTech Autosampler

The MasterTech Autosampler provides assurance that all samples are prepared and analyzed exactly the same way. The MasterTech is designed to increase throughput, repeatability, and reproducibility while reducing operator involvement. Up to 18 samples can be queued to run sequentially and completely unattended, including automatic stirring or sonication prior to transfer to the analysis system. The Saturn DigiSizer II’s operating software controls the MasterTech, and information about dispersion is stored in the sample file for future reference.

The MasterTech features a powerful ultrasonic probe for sample dispersion. Power to the probe tip is adjustable and the driving circuit is self-tuning for maintaining efficient and consistent sonic energy levels. A front-panel digital readout lets you know when the desired power is reached, and that same power is applied each time the method is repeated.

The AquaPrep can prepare 10 liters of water in less than 2 hours (at standard temperature and pressure) and ensures that you obtain the most accurate representation possible of the particle size distribution in your sample.

Superior Data Reduction and Reporting

The Saturn DigiSizer II’s powerful, easy-to-use and versatile user interface provides all the convenient features you expect from a Windows-based program such as point-and-click menus, multitasking capability, copy to clipboard, and more. The familiar Windows format reduces the time required for training and eliminates the need for most off-line data manipulation, resulting in increased productivity. The analysis program is designed to operate in the Windows environment and includes wizards and intuitive screens enabling you to perform system operations quickly and efficiently.

In addition, Micromeritics’ confirm 21 CFR Part 11 software assists with compliance to FDA regulations. Combined with Micromeritics’ IQ and OQ services, the user can be assured that the Saturn DigiSizer II system is validated for accuracy, reliability, consistent performance, and provides safeguards to protect the integrity of analysis records. System access is limited to authorized individuals. Secure, computer-generated, time-stamped audit trails are integral parts of the software program.

Wide Range of Data Presentation Options With many instruments that employ the static light scattering technique, a final report of reduced data typically is the only output available. The Saturn DigiSizer II, however, allows you to access the raw data. For instance, an image of the scattering pattern (2-D and 3-D representations) can be displayed, or you can receive a 592-point intensity versus angle data report in tabular or graphical form. To allow a quick assessment of the fit of theoretical models to experimental data, you also can obtain an overlay plot of measured data calculated from Mie theory.

Reduction of Raw Data Based on Mie Theory Ensures Exceptional Data Quality

Micromeritics employs the Mie theory (or the operator can choose to use Fraunhofer for particles that are both large and opaque) to reduce experimental data using a well-published, non-negative least squares method. These theories describe light scattering via theoretical models. No modifications to the theory are made with the Saturn DigiSizer II, and no assumptions of modality or distribution type are used. This is made possible by the remarkably high resolution of the optical system allowing very narrow size classes to be used in fitting the data to Mie theory.

The application of Mie theory provides unambiguous size data. In addition to reporting the data, the Saturn DigiSizer II can generate a plot that shows how well experimental measurements compare with theoretical Mie calculations for the scattering pattern from the reported distribution.

Revolutionary Approach to Particle Sizing

CCDs were originally developed and used for high-sensitivity and high-resolution requirements of imaging for astronomy. The Saturn DigiSizer II captures the scattering pattern using a patented optical design that employs a CCD as the light detector. A high-definition digital representation of the scattering pattern, which contains all of the information required to determine the particle size distribution, is captured.

Micromeritics’ application of the CCD array eliminates the need for mechanical fine-tuning of optical alignment. The instrument is automatically aligned by re-mapping the CCD array so that the scattering angle assigned to each element is exact to less than 0.005 degree relative to the central, unscattered light beam. The Saturn DigiSizer II’s CCD array has more than three million detector elements. The resulting extremely high resolution makes it possible to detect subtle differences in the scattering patterns and, therefore, subtle differences in particle size distributions. These minute differences in sample particle size may indicate a manufacturing variance, corroborate or refute theoretical studies, or help explain natural processes. Higher resolution means greater knowledge about differences between samples.

Advanced design features enable the Saturn DigiSizer to measure a light scattering pattern over a broad range of scattering angles with a dynamic intensity range from 1 to 1×1010. Combined with the high angular resolution of the CCD, the detector system provides an effective resolution of several million pixels at different positions in the scattering pattern, each detecting minute variations in light intensity. The Saturn DigiSizer’s high resolution enables the instrument to detect extremely small variations in the scattering pattern that are not detected by lower resolution instruments. It is this high level of accuracy that allows the Saturn DigiSizer to provide more detailed and precise particle size information than laser diffraction particle sizing systems of conventional design

What is Air-permeability Particle Sizing?

The air-permeability technique is well established for measurement of the Specific Surface Area (SSA) of a sample powder. The SSA measured by this technique has been found to be a useful parameter in various industries such as pharmaceutical, metal coatings, paints, and even geological samples.

The MIC SAS II utilizes dual pressure transducers to measure pressure drop across a packed bed of powder. By varying the sample height and porosity while controlling the flow rate of air through the sample, the SSA and average particle size can be determined using the Kozeny-Carman equation.

Features and Benefits

Direct Comparison of SAS and FSSS

SentinelPro Unique Design Benefits

Shape Model Descriptions

Circle Models :

• Equivalent circular area diameter
• Equivalent circular perimeter diameter
• Bounding circle diameter
• Mean radius diameter
• Circularity
• Smoothness
• Compactness

Rectangle Models:

• Bounding rectangle length, width
• Bounding rectangle aspect ratio
• Rectangularity

Fiber Models:

• Fiber length, width
• Fiber aspect ratio
• Fiber curl

Ellipse Models:

• Equivalent elliptical area, width, length
• Bounding ellipse width, length
• Elliptical aspect ratio
• Ellipticity

Polygon Models:

• Polygon order
• Interior angle
• Convexity

Irregular Models:

• Feret length, width
• Feret aspect ratio
• Surface uniformity

Two Models Available

SentinelPro Features:

SentinelPro Instrument Features

SentinelPro Software Features

Highly Accurate Zeta Potential Measurements of Concentrated Solutions

Patented FST technology utilizes a transparent electrode to minimize path length and reduce multiple scattering effects. This technology permits accurate zeta potential measurement in a wide concentration range of 0.00001 to 40% (w/v) unique to the ELSZ-2000, eliminating the need to dilute samples.

True Determination of Electrophoretic Mobility

The ELSZ-2000 negates the effects of electroosmosis by measuring zeta potential at five different locations within the cell. As a result, the instrument can calculate and accurately measure true electrophoretic mobility, resulting in a highly accurate determination of zeta potential. This also provides the ability to determine multi-modal distributions of zeta potential mixtures.

Broad Particle Sizing Range with Increased Sensitivity

The ELSZ-2000 has a dynamic sizing range of 0.1 nm to 12.30 µm in a concentration range of up to 40% w/v, and a sensitivity for molecular weight to as low as 250 Da. Dual correlators, log-scale for larger particles prone to time decay and linear scale for small particles, provide high sensitivity measurements in multicomponent samples.

Wide Range of Measuring Cells

The ELSZ-2000 features a wide range of measuring cells available for both zeta and nano particle size measurements. Included is a unique solid sample cell for zeta potential measurement of coated surfaces, films or treated glass slides.

ELSZ-2000 Sample Cells

The ELSZ-2000 has an array of compatible sample cells for both zeta potential and nano particle size measurements. Each sample cell provides additional measurement capabilities of samples in liquid suspensions

Concept of FST Method

FST – Electrophoretic mobility measurement of concentrated suspension using orward cattering through ransparent electrode. By conventional methods, scattered light from a concentrated suspension cannot be measured correctly due to multiple scattering (A). The FST method detects the scattered light from particles through a transparent electrode. The optical path length is minimized to reduce the effects of multiple scattering. Thus, the ELSZ-2000 can perform a zeta potential measurement of a concentrated suspension with a high degree of accuracy (B).

Determination of True Electrophoretic Mobility

When the measurement of electrophoresis is actually taken, an electroosmotic current is generated in the cell due to an electric charge on the cell wall. With a negatively charged cell wall, the electroosmotic flow phenomenon causes the positively charged ions and particles to gather together by the cell walls. The solution located by the cell walls migrates toward the negative electrode during electrophoresis. The solution located in the cell center moves in the opposite direction (toward the positive electrode) to compensate for the flow by the cell walls.

Therefore, an electroosmotic flow is created during electrophoresis. The ELSZ-2000 is designed to measure electrophoretic mobility at several points in the cell to obtain a position (i.e. static) not influenced by electroosmotic flow. As a result, the instrument can calculate and accurately measure electrophoretic mobility, even if the electroosmotic profile of the system is asymmetrical due to adsorption or sedimentation of the sample.

Evaluation of the Surface charge of Solid Sample by Zeta Potential

Novel method to measure the zeta potential of solid surfaces using probong particles.

• Surface charge of the solid sample can be evaluated. Determination of electrostatic interactions between particles and flat surfaces
• Easy to use. Large sample size, min: 14 x33mm, Max: 16 x37mm up to 5mm thickness.
• Solid surface modifications analysis, addictive effect studies and particle adhesion. Zeta potential vs. Ph/additives volume also available
• Wide sample application. Soft sample like fibres can also be measured.

Molecular Weight Determination of Macromolecules with ELSZ-2000:

There are two modes of MW determination of  macromolecules provided by the ELSZ200. The first method is by using dynamic light scattering (DLS) size information with the use of Mark Houwink Sakurada equation and the second method is by using Static Light Scattering techniques (SLS)

The first method uses the diffusion constant obtained from the DLS analysis and by providing two empirical constants associated with the macromolecules–solution under analysis; the molecular weight can be calculated from the Mark Houwink Sakurada equation.

The second method is using Static Light Scattering information in the determination of the Molecular weight of any macromolecules in solution. The scattering intensity is a function of the molecular weight and the concentration of the macromolecule solution as described by Rayleigh equation.

The Scattering intensity of a series of macromolecules solution with known concentrations is being measured. Using a Debye plot, Molecular weight can be calculated by a linear extrapolation line from the Debye Plot.

Proven Technique and Reliability

For over three decades, the Micromeritics SediGraph has remained the standard instrument for particle size analysis in many laboratories throughout the world. Whether in a rugged production environment or a controlled laboratory setting, the SediGraph continues to produce accurate results with superior reliability. Particle size distribution is measured using the sedimentation method. Particle mass is measured directly via X-ray absorption. By measuring the rate at which particles fall under gravity through a liquid having known properties as described by Stokes’ law, the SediGraph determines the equivalent spherical diameter of particles ranging from 300 to 0.1 micrometers.

Intelligent Design Features

The SediGraph III Plus offers advanced instrumentation features that ensure measurements are repeatable and easy to perform. New features make it easier to operate and maintain the instrument, and the results can be reliably reproduced by SediGraphs in other locations.

A Wide Variety of Benefits:

Complete particle accountability

Assures that all of the introduced sample is accounted for, including fractions below 0.1 µm

Capability to merge data

With that from other particle sizing methods, thus extending the range of reported data to 125,000 µm (125 mm), excellent for geological applications

Scanning the sedimentation cell

From bottom to top allows accurate inventory of fast-settling particles while minimizing the time required to resolve the separation of fine particles

Fully automatic operation

Increases sample throughput and reduces operator involvement in addition to reducing the opportunity for human error

Temperature-controlled analyses

Assure that liquid properties remain constant throughout the analysis so you can be confident of accurate and reproducible results

Multiple analysis speeds

Allow you to choose the desired combination of speed and resolution that meets your needs

Real-Time display

Allows you to monitor the cumulative mass plot of the current analysis and to make immediate procedural changes if needed

Statistical process control (SPC) reports

Track the performance of your processes allowing immediate response to fluctuations

Plot overlays

Provide a visual comparison of analysis results from one or more analyses; a reference or baseline analysis, for example, or a superposition of two different types of plots of the same analysis data

Data comparison plots

Provide graphical displays of the mathematical difference between two data sets (difference from reference plot) or the extent of a data point value above or below a tolerance boundary (out of specification plot)

Applications

Ceramics :

The size range of particles and the distribution of mass in each size class strongly affect the ability to sinter a ceramic powder and its forming properties as well as the pore size distribution in the finished product. Particle size distribution information helps determine curing and bonding procedures, control pore structure, ensure adequate green body strength, and produce a final product of desired strength, texture, appearance, and density.

Pigments:

Particle size alone can affect the tinting strength of a color. As tinting strength goes up, the quantity of pigment needed to produce required color intensity goes down. The particle size affects the hiding power of the paints. Also the particle size distribution influences gloss, texture, color saturation and brightness.

Geological/Soil Science:

Grain size affects the moisture-holding capacity of soil, drainage rate, and the soil’s ability to hold nutrients. Grain size is directly related to transport of sediment.

Cosmetics:

The appearance, application, and packaging of cosmetics are influenced by the particle size distribution of base powders, such as talc, and the pigments used for coloring.

Metal Powders:

By controlling particle size, very specific pore characteristics can be designed into a product. Porosity characteristics often are the key to product performance. Similar to ceramics, the particle size distribution is critical to green body and final product strength and density.

Catalysts:

Particle size affects the catalytic activity of a metal for structure-sensitive catalytic reactions.

Minerals and Inorganic Chemicals:

Reactivity of materials is dependent upon exposed surface area and thus particle size distribution.

Abrasives:

A properly balanced size distribution of abrasive grains and powders is a fundamental consideration whether the material is to be used in slurries, dry blasting, or bonded abrasive tools. Uniform particle size assures precise flow rates through blast machines and is a critical determination in media management when recycling the abrasive material.

The Endurance of the SediGraph Method

The SediGraph has been employed in a wide variety of industrial applications since its embodiment into a commercial instrument in 1967. To confirm its wide use in various applications throughout the world,one needs only to type in ‘SediGraph’as the search key for any Internet search engine.The instrument has undergone many improvements in speed, sample handling,and data reduction and reporting since its introduction. However, the fundamental analytical technique continues to be based on two well-established and well-understood physical phenomena—sedimentation and photon absorption. Stokes’ law is applied to determine particle size by measurement of the terminal settling velocities of sample particles of various sizes. Relative mass concentration for each size class is determined by applying the Beer-Lambert-Bouguer law to the measured absorption of a low-power X-ray beam projected through the fraction of sample remaining in suspension. The elegant simplicity of the Stokes and Beer-Lambert-Bouguer laws means that interpretation of raw data is straight-forward; the analyst easily can understand the relationship between the basic measurements and the reported size distribution. All experimental parameters are easily determined, data reduction is uncomplicated and fast, and there is no requirement to ‘bias’ the data reduction software toward a particular distribution modality.

Stokes’ Law

Stokes’ law simply states that the terminal settling velocity of a spherical particle in a fluid medium is proportional to the square of the diameter of the particle. Stokes’ law applies rigorously providing that a certain relationship between these variables, the particle diameter and the settling velocity, is not violated. Application: if a collection of particles of various diameters is uniformly dispersed in a liquid of density less than that of the particles and then allowed to settle under gravity, it accurately can be predicted when all particles below any given size will have fallen below any given level. The size distribution of the particles can be extracted from this information. For a detailed description of the SediGraph technique refer to ISO 13317-3:2001 Determination of particle size distribution by gravitational liquid sedimentation methods – Part 3: X-ray gravitational technique.

Sedimentation, X-ray Absorption

The SediGraph uses a narrow collimated beam of X-rays to measure directly the particle concentration in the liquid medium. This is done by first measuring the intensity of a baseline or reference X-ray beam which is projected through the cell windows and through the liquid medium prior to the introduction of the sample. A homogeneously dispersed mixture of solid sample and liquid is next pumped through the cell. The attenuated X-ray beam is measured to establish a value for full scale attenuation. Agitation of the mixture is ceased and the dispersion is allowed to settle while X-ray intensity is monitored. During the sedimentation process, the largest particles fall below the measuring level, and progressively finer and finer particles do so until only the finest remain near the top of the measuring cell.

Quality Measurement Results

Critical decisions or conclusions may be based on size measurements, therefore your confidence in the quality of those measurements should be well-founded. Data accuracy is particularly important in research applications. Accuracy describes how closely the measurement agrees with the accepted or ‘true’ value. Repeatability and reproducibility are of equal importance in quality control applications. Repeatability describes the ability to produce the same results over a series of measurements of the same sample. Reproducibility of measurements usually pertains to different instruments in different facilities, an important instrument quality in assuring that each facility will produce equivalent products.

Extremely Versatile Data Presentation and Reporting Software

The SediGraph III 5120 is equipped with a versatile, easy-to-use user interface that provides all of the convenient features you expect from a Windows^®-based program.These features include point-and-click menus, customizable reports with your laboratory logo graphic, editable graphs, cut-and-paste graphics and tables, data export features, and more. Custom protocols help plan, launch, and control the analysis and assure that subsequent analyses are all performed in the same manner, regardless of the skill of the operator. You can collect, organize, archive and reduce raw data, and store standardized sample information and analysis conditions for easy access during later applications. Finished reports may be generated to screen, paper, or transferred in a variety of formats to storage devices.

Data Reporting

Detailed analysis data for particles ranging from 300 to 0.1 μm are provided automatically by the SediGraph III. Data collected from other particle size analyses ranging from 125,000 to 300 μm can be combined with SediGraph data, enabling effective reporting for particles ranging from 125,000 to 0.1 μm. That fraction finer than 0.1 μm is also indicated.

In addition to tabular data, different graphical analysis plot types are available including:

• Cumulative Mass, Area, and Number
• Settling Velocity Distribution
• Process Control Charts
• Log Probability
• Baseline/Full Scale References
• Frequency Distribution
• Difference From Reference
• Out of Specification
• Rosin-Rammler
• Regression Analyses

Plots can be over-laid for comparing the results from different samples or for comparing different plot types from the same sample.This allows you to compare analysis results to a standard. Plots can be rescaled to give you the ability to scrutinize closely your graphical data.

A new column has been added to the tables and to the x-axis selection in the graphs that reports size in Phi units, where Φ= -log₂ (particle diameter in mm). Also, a column selection for settling velocity (cm/s) is available for tables. The x-axis of plots can be scaled in particle size or settling velocity.The SediGraph is the only automated particle sizing instrument that directly measures settling velocity.

SPC Reporting and Regression Analyses

Statistical Process Control (SPC) reporting provides an easy method for continuously monitoring production processes and reducing response times to deviations from the standard. Regression analyses allow you to determine the relationship between a control parameter, for example, and a measured characteristic of the sample.

Select from 26 axis variables including:

• Mean
• Mode
• Median
• Size at (percentile)
• Standard Deviation
• Coefficient of Variation
• – N σ Size
• + N σ Size
• Skewness
• Kurtosis
• Specific Surface Area
• Cumulative Percent at Size
• Percent Out of Specification
• Full Scale Scan Pump Speed
• MasterTech Stirrer Speed
• MasterTech Stirrer Time
• MasterTech Ultrasonic Probe Time
• Particle Density
• Liquid Viscosity
• Liquid Density
• Three User-defined (External) Parameters

Elzone II Advantages

• Counts and sizes organic and inorganic materials
• Suitable for analyzing samples of mixed optical properties, densities, and shapes
• Higher resolution than with other particle sizing methods
• Low quantities of sample are analyzed accurately and easily
• Compact size conserves laboratory bench-space
• Plot overlays make comparing analysis results with those of product standards or other analysis results easy
• Extensive statistical analysis and data presentation features included Liquids can be used without knowing viscosity or optical properties
• A variety of conductive liquids can be used without knowing viscosity or optical properties
• Does not require previous knowledge of sample properties (density, refractive index)
• Plot overlays make comparing analysis results with those of product standards or other analysis results easy
• Optional Confirm 21 CFR Part 11 software assists with compliance to FDA regulations. IQ and OQ services help assure that the system is validated for proper installation, accuracy, and consistent performance.

Ease of Use

• Automatic start-up, run, and shut down routines
• Automatic blockage detection and clearing
• Automated flushing/rinsing
• Automatic or manual calibration to accommodate different particle types and shapes