The maximum size specification (diameter) for the Zetasizer Nano S or ZS instrument is a peak mode of 8.9 µm with a maximum size of 10 µm. This article contains information on the experimental procedures and results acquired from the measurements of a NIST traceable polystyrene latex standard as demonstration of these maximum size specifications.
- From the Thermo Scientific Duke Standards NIST traceable 4000 series (part number 4209A), 8.9 µm polystyrene latex is supplied at a 1% w/v concentration
- Sizing cuvettes
- 21.7% w/v sucrose
To prepare a 21.7% w/v solution of sucrose, a 21.7 g of sucrose was taken which was made up to 100 g with deionized water. Next, a 400 µl of the latex was added to 600 µl of the sucrose solution to prepare a polystyrene latex standard sample for measurement. This dilution offered a final polystyrene latex concentration of 0.4% w/v in 13% w/v sucrose. This dispersant was selected to match the density of the latex, which has a density of 1.05, to avoid sedimentation.
By using a viscosity of 1.41 mPa.s, the measurements were taken at 20 °C.
Figure 1 demonstrates the intensity size distributions obtained from three repeat measurements of the 8.9 µm polystyrene latex dispersion. The sucrose peak is not observed as the scattering is affected by the scattering from the latex.
Figure 1. Intensity size distributions obtained from 3 repeat measurements of a traceable 8.9 µm polystyrene latex suspended in 13% w/v sucrose solution.
Table 1 shows an outline of the three repeat measurements and depicts the polydispersity index values and z-average diameters (in nanometers) obtained, along with the standard and mean deviation values.
Table 1. Summary of the 3 repeat measurements of a traceable 8.9 µm polystyrene latex suspended in 13% w/v sucrose solution
||z-Average Diameter (nm)
Figure 2 depicts the overplot of the three correlation functions, from which the size distributions were derived from. Following the signal decay, the baseline on the right of the plot, which although shows the proof of some noise, does not reveal the effects of number fluctuations. This would appear as secondary peaks in the correlation function, indicating that the optical design of the Zetasizer Nano S and ZS instruments is intrinsically capable of measuring particles of this size.
Figure 2. Correlation functions obtained from 3 repeat measurements of a traceable 8.9 µm polystyrene latex suspended in 13% w/v sucrose solution.
In this article, the above results prove that the maximum size capability (diameter) for the Zetasizer Nano S or ZS instrument is a peak mode of 8.9 µm with a maximum size of 10 µm.
This information has been sourced, reviewed and adapted from materials provided by Micromeritics Instrument Corporation.
For more information on this source, please visit Micromeritics Instrument Corporation.