Traceable methods for calibrating condensation particle counters at concentrations down to 1 cm−3

• Published in: Metrologia 2023-10, Vol.60 (5), p.55012
• Main Authors: Sakurai, Hiromu, Murashima, Yoshiko, Iida, Kenjiro, Wälchli, Christian, Auderset, Kevin, Vasilatou, Konstantina
• Format: Article
• Language: English
• Subjects: calibration; condensation particle counter; counting efficiency; Diameters; Dilution; Measuring instruments; number concentration; Polystyrene resins; primary standard; Radiation counters
• ISSN: 0026-1394; 1681-7575
• DOI: 10.1088/1681-7575/acf5f1

The concentration of nanometer-sized particles is frequently measured in terms of particle number concentration using well-established measuring instruments, such as condensation particle counters (CPCs). Traceability for these measurements can be achieved by means of calibration against a reference aerosol electrometer starting at concentrations >1000 cm −3 . Here, two independent methods for extending traceability down to 1 cm −3 are described. The first method relies on a custom-made, reference optical particle counter while the second method combines electrometer measurements with a series of dilution steps. An inter-comparison of the two methods was carried out using polystyrene spheres with a nominal diameter of 100 nm in the concentration range 1 cm −3 –100 cm −3 . A CPC Model 3752 (TSI Inc, USA) was used as transfer standard. The obtained results showed a deviation of 1%–4% between the two methods, which was in agreement with the stated uncertainties.