A broad range of particle standards, with sizes as small as a few nanometers in diameter, are readily available whose sizes have been measured by NIST-traceable methods. In these cases, at least the mean particle size can be known with good certainty.
But what about for concentration? Currently, no reference standards for concentration exist in sizes below about 1 μm in diameter, and in many cases particle manufacturers do not even provide an estimate of particle concentration for their products. What is a responsible scientist to do when planning an experiment in which the concentration of particles in the sample is critical?
As a first step, you can input some basic information about the standard (e.g., weight percent solids, particle material density, mean particle diameter) into Spectradyne's online calculator to obtain an estimate of concentration. This calculator assumes that the particles are all the same size, equal to the mean particle diameter, and calculates the concentration in units of particles per milliliter.
Of course, the true concentration of the sample depends on the details of its particle size distribution-so for a more accurate measurement of concentration over any size range the sample should be analyzed using Spectradyne's nCS1TM!
For a demonstration of how particle standards can be used in-situ as a built-in validation of your measurements on the nCS1, check out this video!