ASTM E 3427:2024

1.1 The technology, laser-amplified detection/power spectrum analysis (LAD/PSA), is available in three different platforms, which will be designated as Platforms A, B, and C. 1.1.1 Platform A- This is a solid-state probe configuration that serves as the optical bench in each of the platforms. It consists of an optical fiber coupler with a y-beam splitter that directs the scattered light signal from the nanoparticles at 180° back to a photodiode detector. The sensing end of the probe can be immersed in a suspension or positioned to measure one drop of a sample on top of the sensing surface. 1.1.2 Platform B- The same probe is mounted in a case, positioned horizontally, to detect the signal from either a disposable or permanent cuvette. 1.1.3 Platform C- Two probes are mounted in a case, horizontally, at opposite sides of a permanent sample cell. Both size distribution and zeta potential can be measured in this configuration. 1.2 The laser beam travelling through the probe measuring the scattered light from the sample of nanoparticles, in all three platforms, is partially reflected back to the same photodiode detector, and the high optical power of the laser is added to the low optical power of the scattered light signal. The interference (mixing or beating) of those two signals is known as heterodyne beating. The resulting high-power detected signal provides the highest signal-to-noise ratio among dynamic light-scattering (DLS) technologies. 1.3 This combined, amplified, optical signal is converted with a Fast Fourier transform (FFT) into a frequency power spectrum, then into a logarithmic power spectrum that is deconvolved into number and volume size distributions. The mean intensity, polydispersity, number and volume size distributions, concentration, and molecular weight can be reported in all platforms, plus zeta potential on Platform C. 1.4 This technology is capable of measuring nanoparticles in a size range from 2.0 nanometres (nm) to 10 micrometres (µm), at concentrations in a suspending liquid medium up to 40 % cc/mL for all parameters given in 1.3 . 1.5 Units- The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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