2023 年 60 巻 7 号 p. 414-421
The number concentrations of liquid-borne particles are widely measured in various settings such as in semiconductor industries, clinical laboratory testing, pharmaceutical industries, and maintenance for industrial machineries. These industrial fields need quality control for the particle number concentration measurements by using reliable metrological standard. To establish the traceability in measurements of the particle number concentration from sub-micrometer to micrometer size range, we have developed an SI-traceable measurement method. We refer to this method as mass-measurement-type optical particle counting (M-OPC) method. The M-OPC method is based on single-particle optical particle counting method. Adopting two different type of optical particle counters having different measurable size ranges enables our calibration service to cover a wide range of particle diameters from sub-micrometer to micrometer level (600 nm–10 μm). This paper reviews the principle of the M-OPC method and the evaluation procedure of the particle number concentration including the uncertainty analysis. We also report the results of the verification tests for 600 nm, 2 μm, and 10 μm to confirm the validity of the M-OPC method in the above size range by using polystyrene latex (PSL) particles suspensions.
