DLS measurements of the apparent diameter of 30 nm PSL particles obtained in pure water at NMIJ, dapp (○, Δ, +, ×, and ◊) and NIST, ZAVE (filled squares). The concentrations (× 1012 particles mL−1) at NMIJ are 130 (○), 110 (Δ), 81 (+), 54 (×), and 27 (◊). The concentrations (× 1012 particles mL−1) at NIST are 190, 120, 78, 52, 33, 27, 19, and 14. Error bars as in Fig. 1.