In a COULTER COUNTER instrument, a tube with a small aperture on the wall is immersed into a beaker that contains particles suspended in a low-concentration electrolyte. Two electrodes, one inside the aperture tube and one outside the tube but inside the beaker, are placed and a current path is provided by the electrolyte when an electric field is applied. The impedance between the electrodes is then measured. The aperture creates what is called a “sensing zone”. Particles in low concentration can be counted by passing them through the aperture. As a particle passes through the aperture, a volume of electrolyte equivalent to the immersed volume of the particle is displaced from the sensing zone. This causes a short-term change in the impedance across the aperture. This change can be measured as a voltage pulse or a current pulse. The pulse height is proportional to the volume of the sensed particle. If constant particle density is assumed, the pulse height is also proportional to the particle mass. This technology is also referred to as aperture technology. If the volume of liquid passing through the aperture can be precisely controlled and measured, the sample concentration can also be determined.

  Beckman Coulter Multisizer 4e Particle Sizer and Counter builds on the original proven technology Coulter Principle ISO 13319 with 9 approved ASTM methods & documented references has more than a century of experience on high resolution accurate counting and sizing particles and cells base on direct measurement of its volume not affected by the optical properties at concentration levels.

  Beckman Coulter Multisizer 4e which utilize this principle are called COULTER COUNTER, designed with selection of aperture (Nominal Diameter,10µm ~ 2000µm) thus measuring range of 0.2µm to 1600µm, from Liposome size of pharmaceutical; yeast & flavor emulsions for food & beverage; industrial powder of toner, abrasives & cosmetics; to biological sector such us algae, amoeba in marine biology, cell biology & micro biology of bacteria & mold. Over 8,000 references to the uses of this technology have been documented.

  The Multisizer 4e builds on the original Coulter Principle, adding a Digital Pulse Processor DPP incorporates the latest advances in both analog and digital circuits for ultra-high resolution. High-speed digitalization enable multiple-channel analysis and accuracy unattainable by other technologies. In addition, the smart technology integrated into the Multisizer 4e makes it incredibly easy to use with simpler and cleaner reagent handling, improved sample management which include aqueous and organic fluids volumetric metering pump, barcode reader, EZAccess fluid management system, electronic aperture blockage detection, automatic startup user-selectable routine, improved performance in dusty environments, reduced noise and an overall uniform testing environment for repeatable, reliable results. Dynamic size measurement on the Multisizer 4e, pulse time stamp allows size change measurement in real time. The measurement data for each particle is analyzed and stored. The data can be analyzed and formatted in numerous ways, or stored and re-analyzed at a later date – no need to analyze the sample again.

  Combined with biological researcher-friendly, quality assurance-friendly 21 CFR Part 11 compliance intuitive software, a stream of multiple parameters such as accurate sizing, counting and high resolution for particle counting and size distribution that described by the entire pulse magnitudes that rise and fall associated to different factors; natural or induced by man during the length of the analysis; as particles pass through the aperture are saved. This is practical tool to study volume changes associated to different process & time where particles could change during the length of the analysis for example in studies involving: solubility, crystal growth, sample stability, agglomeration, bubble generation. The powerful and flexible software provides size and pulse data in numerous formats. A broad range of statistical parameters are automatically calculated and the results are presented in a customized report. With build in wizards that ideal for both beginners and experienced operators to process and present of data to fit all needs, including industrial, biological, academic applications and for research and quality control .

  The Multisizer 4e software methods are divided into standard operating methods (SOMs), standard operating procedures (SOPs) and user preferences. An SOM is used to specify sample analysis settings such as file naming conventions, number of size bins to output the data, and sample concentration information. User preferences include Graph display and Statistics settings. An SOP consists of an SOM file Combined with a preferences file.

  Automated calibration and calibration verification included for reliable results for both size and counts.