Certified Viscosity and Particle Size Standards

By: Matthias Nold, AnalytiX Volume 9 Issue 3

Matthias Nold, Product Manager Analytical Standards matthias.nold@sial.com

Sigma-Aldrich® offers a wide range of physical properties standards for various applications in the chemical, food and material science industries. These include standards for density, melting point, conductivity, molecular weight (MS markers), pH calibration, Redox, turbidimetry and X-Ray as well as colour reference standards (see page 4 to 6). To get an overview of the physical property standards available from Sigma-Aldrich, please visit our website at: sigma-aldrich.com/physicalproperties

Recently, new certified reference materials for particle size, as well as for viscosity, were added to our portfolio. These reference materials are manufactured and certified in the United Kingdom by internationally recognised specialists at Whitehouse Scientific Ltd. and Paragon Scientific Ltd. respectively.

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Polydisperse Particle Size Standards and Sieve

Certified Polydisperse Particle Size Standards

These NIST and NPL traceable standards were commissioned by the Bureau of Certified References (BCR) and are measured by a large international team including the 20 top laboratories in the field of particle size. For the certification of the glass particles, several unambiguous primary methods such as microscopy, sieving, sedimentation and Coulter counter were used.
The standards are delivered in sets of 10 vials in quantities suitable for any method of analysis without further subdivision.


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Certified Sieve Calibration Standards

The Sieve Calibration Standards from Whitehouse Scientific offer a unique method of calibrating sieves with traceability to NIST and NPL. The glass microspheres are delivered in sets of single shot bottles in order to eliminate operator-sampling errors.

The calibration requires only about two minutes, following a simple procedure: the glass microspheres are placed into the sieve, which is shaken either manually or mechanically, until an equilibrium has been reached and no more particles pass through the sieve. By weighing the sieve and the single shot bottle before and after the calibration, the percentage of microspheres passing through the sieve can be calculated and the mean aperture size of the sieve can thus be determined using the calibration graph supplied with the test certificate. Figure 1 shows an example of a calibration graph for the 63 μm sieve standard.

Figure 1. Calibration graph for the 63 μm sieve standard

Figure 1. Calibration graph for the 63 μm sieve standard

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Viscosity Standards from Paragon Scientific

Accurate viscosity measurements play an important role in various fields of industry, such as food and beverages, paint and coatings and the pharmaceutical and petroleum industries. For the calibration and verification of viscosity measuring equipment, analytical standards with known viscosity are needed.

We are pleased to present 26 viscosity standards from Paragon Scientific, which have been recently added to the portfolio. These standards are produced in theUnited Kingdom in an ISO 17025 certified laboratory. They are manufactured in strict accordance with ASTM D 2162 (Standard Practice for basic calibration of master viscosity standard oils) and are traceable to NIST.

In the certificate, the viscosity values and density are stated at various temperatures as well as the expiry date and uncertainties. The viscosity values are given as kinematic viscosity (mm2/s (cSt)) and as dynamic viscosity (mPa*s (cP)) for all temperatures.

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