• These microspheres show a size distribution which is appropriate for methods that need particle size uniformity between monodisperse (highly uniform, <5% CV**) and polydisperse (widely distributed, <12% CV). These include instruments for light blockage, light diffraction, acoustical imaging, electrolyte displacement or other methods used for analysing wide size range materials. The material is composed of polystyrene cross-linked with divinylbenzene. This gives the particle good durability and chemical stability. They can be washed in water-alcohol mixtures and resuspended in water, air or similar media. The density of polystyrene is 1.05 g/cm3, and the index of refraction is 1.59 at 589nm (25C). Microspheres in this series are packaged as an aqueous suspension in 15 mL dropper-tipped vials.
  • This series of NIST traceable size standards provides an accurate and convenient method for calibrating or checking the performance of laser particle counters used in cleanrooms and other contamination monitoring applications. The products are suspensions of monodisperse polystyrene spheres (PSL) for use in airborne or liquid particle dispersion systems. They are available in a range of sizes from 0.1 to 100µm in diameter. The particles are prepared as low residue aqueous suspensions for minimal background interference, packaged in 15mL dropper-tipped vials. The particle diameters are calibrated by electron or optical microscopy. Each package includes a Certificate of Calibration and Traceability to the National Institute of Standards and Technology (NIST). In comparison with the well established 3000 and 4000 Series products described elsewhere, these product lines are precisely diluted for immediate use in laser particle counters with minimal time-consuming adjustments of concentration.
  • These uniform microspheres are NIST-traceable by calibration methods such as optical microscopy. Products from 1 to 160µm in diameter are packaged as aqueous suspensions of polystyrene spheres in dropper-tipped bottles. Diameters of 200µm and larger are packaged as dry spheres in screw-capped bottles. These larger particles are composed of polystyrene DVB (divinylbenzene). The spheres have a density of 1.05g/cm3 and an index of refraction of 1.59 @ 589nm.
  • Calibrate airborne optical particle counters (OPC) to comply with ISO 21501-4 regulations with the Thermo Scientific™ 4D Series Dry Microsphere Size Standards. Ideal for instrument manufacturers, as well as QA/QC managers in pharmaceutical, biotech and electronics manufacturing, these microsphere reference beads feature a calibration uncertainty—the range of values within which the actual mean diameter will lie—that is less than or equal to 2.5% of the mean diameter. 4D Series are available in 4 different nominal sizes: 3, 5, 7 and 10µm.
  • Fluorescent beads 488nm excitation and 500 - 700nm emission, 7µm uniform in size for absolute counting of cells.
  • Thermo Scientific provides these products for calibrating particle counters which require dry particles, from 5 to 100 µm. They are conveniently packaged in dropper-tipped vials in 1 gram quantities, enabling the user to dispense the microspheres directly into the sampling chamber. They are not suitable for dispersion in liquid media. The mean diameters are traceable to the National Institute of Standards and Technology (NIST). DRI-CAL™ Particle Size Standards are composed of polystyrene DVB (divinylbenzene) and have a density of 1.05g/cm3. The refractive index is 1.59 @ 589nm. The certified mean diameter was determined by optical microscopy using a NIST calibrated stage micrometer. Size distribution was determined by electrical resistance analysis.
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