THE microReport The Science and Technology of Small Particles™ M ICROMERITICS I NSTRUMENT C ORPORATION VOLUME 16 NO. 1 In This Issue New Elzone Combines New Elzone Combines Modern Technology with Modern Technology with Proven Method New Elzone available in Proven Method 2005 .....................................1 icromeritics is prepar- Micromeritics’ Tony Thornton ing to release our new Appointed Chairman of ISO MElzone® II 5390 particle Committee on Particle Sizing sizing and counting instrument. Will assist in the establishment The Elzone series is based on the of U.S. and International “electrical sensing zone” tech- Particle Sizing Standards...3 nique, also known as the “Coulter Principle.” The first instru- Micromeritics Showcases ment of this type was invented Instruments at the in the 1950’s by Wallace H. Pittsburgh Conference.......4 Coulter, founder of the Coulter Corporation, and it quickly Perform Longer Surface became the preferred method for counting blood cells. Area Measurements with The Gemini Today, this technique is widely accepted and recognized as New Gemini allows for longer analysis times..........5 a highly effective method of sizing and counting particles composed of a wide variety of organic and inorganic materi- What’s New at Micromeritics als. Unlike other particle measurement techniques such as Analytical Services ...........6 laser light scattering, sedimentation, or image analysis, the electrical sensing zone method can analyze samples of vary- Also... ing optical properties, densities, colors, shapes, and orienta- Training Courses.................7 tions. Micromeritics’ Elzone particle size analyzer uses this Events..................................7 powerful particle characterization technique to determine quickly and accurately the size, number, concentration, and mass of a wide variety of finely divided materials. It determines particle diameters from approximately 0.4 µm extending to nearly three orders of magnitude larger – a dynamic size range suitable for a wide variety of industrial, biological, and geological specimens. An Elzone analysis begins by taking a sample (a dry pow- der, paste, or emulsion) and dispersing it at low concentra- tion in an electrolyte solution. This dispersion is placed in www.micromeritics.com VOL 16 NO 1 VOL 16 NO 1 a sample cup that contains the majority of cases, par- and some external parameter an electrode. The sealed end ticles pass through the orifice that is entered by the user, of a glass tube is immersed one at a time. Thus, coinci- for example, grinding time. in the dispersion. In the side dence error is largely elimi- of this tube and below the nated from measurements by A novel feature available with liquid surface is a precision the low particle concentration the new Elzone® II 5390 takes hole (orifice) through which that is required to perform advantage of the pulse width the electrolyte is drawn by an analysis. However, there data that are recorded with maintaining a specific pres- remains some finite probabil- each pulse height data point. sure differential across the ity that two or more particles The amplitude of the pulse orifice. Within the glass tube will be within the orifice vol- is related to volume, but for is another electrode of oppo- ume simultaneously. To com- a given flow rate and pulse site polarity from the exterior pensate for these events, coin- amplitude there may be vari- electrode. A conductive path cidence correction algorithms ous pulse widths. One way is formed between the elec- are applied. this may be accounted for is trodes with current flowing by particle shape. Micromeritics’ way of the electrolyte through The advantage of this par- new Elzone presents these the orifice. As the electrolyte ticle sizing technique is its data as a three-dimensional is pulled through the orifice, high precision and very high plot of particle size, pulse so are suspended particles. resolution, defined as the width, and quantity of par- Each particle while in the minimum width of the size ticles. orifice displaces a volume of increment (class) that can be electrolyte equal to its own discriminated. The Elzone Examples of Applications volume. Displacement of the produces fidelity of sizes of That Benefit from Sizing electrolyte impedes the cur- 95% or better when a narrow by Elzone Analyzers rent flow through the orifice, span standard material is There are a number of mate- that is, it increases circuit measured and a comparison rials for which this type resistance, decreasing con- is made between the ratio of of particle size analysis is ductivity. This produces an true width to measured width uniquely suited. For example, electrical pulse, the amplitude of the particles. The Elzone is today’s toner manufactur- of which is proportional to the easily calibrated to produce ers have a need to produce particle volume. The Elzone precision and reproducibility microfine toners that have counts the pulses and sorts of results to within ± 2%. very narrow size distribu- them by amplitude (volume) tions, both by volume and and pulse width (related to The instrument reports data population. The Elzone data transit time). This provides as volume percent, popula- are crucial in determining to data from which are calculat- tion, or surface area distribu- what extent this objective has ed the particle population in tion in cumulative or differ- been met by sizing and count- a variety of relative and abso- ential form on linear or log ing particles essentially one lute dimensions. A precision scales following the guidelines at a time with the accuracy of metering pump also is avail- of International Standards electronically based volume able allowing concentration to ISO 13319. Plots can be over- displacement technology. In be determined. laid for comparisons and data this application, the combina- from a series of analyses can tion of high resolution and The small diameter of the ori- be reported in Statistical the ability to count makes fice and its short length mean Process Control charts or as electrozone sensing a natural that it has a small internal ‘cause and effect’ plots using choice. volume. If the number con- linear regression to determine centration of the suspension what degree of correlation The Elzone has also found a is considerably less than one exists between a dimension place in the determination particle per volume, then in measured by the instrument of particle-size distributions 2 3 VOL 16 NO 1 VOL 16 NO 1 Micromeritics’ Tony Thornton of packing materials used for high performance liquid Appointed Chairman of ISO Sub- chromatography (HPLC). Both particle size distribu- Committee on Particle Sizing tion and average particle Will Assist in the Establishment of U.S. and International diameter are required mea- Particle Sizing Standards surements since packing material performance from different lots can vary icromeritics’ Senior greatly even though the lots Product Scientist Tony appear to have the same MThornton has recently average particle size. Lots been appointed Chairman of the ISO Technical Committee are evaluated based only on 24 (Sieves, Sieving and Other one of these parameters. For Sizing Methods) sub-commit- this application, particle size tee 4 (Sizing by Methods Other distributions are enhanced Than Sieving). His years of by the high-resolution capa- technical contributions and bility of the electrical sens- involvement with both ASTM ing zone technique allowing and ISO have distinguished subtle shifts in the distribu- him as a respected expert in tion to be observed. the field of particle character- ization, and his work has been Geological materials such instrumental in the establish- spoken at numerous technical as soil, silt, and sediments ment of standard methods in seminars on powder character- are composed of a variety this field. ization techniques, imparting of components, both organic information that serves as the and inorganic. Accurate Last Spring, Tony received basis for ASTM standard test sizing by sedimentation the ASTM Award of Merit methods and revisions. This requires that the sample be for outstanding technical information extends to the composed of materials of the contributions to and master- international arena, serving same density. Light scatter- ful leadership of Committees also as input to ISO standards ing techniques require that B09 on Metal Powders and based on the ASTM versions. Metal Powder Products, and all particles have essentially E29 on Particle and Spray the same optical properties. Tony is currently Micromeritics’ Characterization. He has Senior Product Scientist and Both techniques are sensi- actively and productively par- Training Manager. He also tive to particle shapes that ticipated in several ASTM com- assists with methods develop- vary greatly from spherical. mittees for more than 16 years. ment, applications support, and Sizing by electrical sensing analyses intrepretation. zone is not affected by these He has also served as liaison characteristics of a sample. among ASTM Committees B09, MIC is proud of Tony’s con- E29, C21, and C28 all dealing tributions to the field and is Although the electrical in some capacity with analysis fortunate to have his expertise sensing zone technique was of powder materials, his area supporting our line of particle introduced to count blood of expertise. He has ensured sizing products. cells, it now provides excel- that the standards written by lent measurements on a all these committees are tech- wide array of materials. nically similar,