Number Concentration Measurements of Polystyrene Submicrometer Particles

Area of Science:

• Nanotechnology
• Metrology
• Analytical Chemistry

Background:

• Increasing number of techniques for submicrometer particle measurement.
• Need for submicrometer particle standards to enhance accuracy and reproducibility.
• Current methods show variability in measuring particle number concentrations and size distributions.

Purpose of the Study:

• To assess the accuracy and reproducibility of different techniques for measuring submicrometer particle number concentrations.
• To evaluate the suitability of polystyrene spheres as submicrometer particle standards.
• To propose a protocol for certifying SI-traceable number concentration standards.

Main Methods:

• Measurement of number concentrations and diameters of 100 nm, 200 nm, and 500 nm fluorescently labeled polystyrene spheres.
• Utilized seven different measurement techniques.
• Three techniques were employed to determine SI-traceable number concentration values.

Main Results:

• Diameter measurements agreed within 20% across techniques.
• Number concentration measurements varied by as much as a factor of two.
• Identified significant discrepancies in particle number concentration determination.

Conclusions:

• Submicrometer particle standards are crucial for instrument calibration and inter-technique comparability.
• A consensus approach using SI-traceable values is proposed for certifying particle number concentration standards.
• Standardization is essential for reliable submicrometer particle metrology.