Validation of a Homogeneous Incremental Centrifugal Liquid Sedimentation Method for Size Analysis of Silica (Nano)particles

Abstract

Silica nanoparticles display many unique physicochemical properties that make them desirable for use in a wide variety of consumer products and composite materials. Accurately measuring the size of these nanoparticles is important for achieving the desired nanoscale functionality of the final product and for regulatory compliances. This study covers the validation of a centrifugal liquid sedimentation method for accurate measurement of the Stokes diameter of silica particles with a near-spherical shape and dimensions in the nanometer and sub-nanometer scale range. The validated method provided unbiased results in the range of 50 nm to 200 nm, with a lower limit of detection of ≤20 nm. The relative standard uncertainties for precision, quantified in terms of repeatability and day-to-day variation, ranged from 0.2% to 1.0% and from <0.1% to 0.5%, respectively. The standard uncertainty for trueness was assessed at 4.6%. Within its working range, the method was found robust with respect to the type of cuvette, light factor, operator, and for defining the meniscus of the sample suspension. Finally, a relative expanded measurement uncertainty of 10% confirmed the satisfactory performance of the method.

Guidance on risk assessment of nanomaterials to be applied in the food and feed chain: human and animal health

“…Measurement uncertainties should be reported as combined uncertainties for the entire process. They can be derived from data obtained during a validation study; examples are available for measurements based on TEM (De Temmerman et al., 2014), DLS (Braun et al., 2011), PTA (Kestens et al., 2017; Ramaye et al., 2021), CLS (Antunez‐Dominguez et al., 2020) or ELS (Ramaye et al., 2021). The measurement uncertainty associated to measurement results obtained during routine application of the validation method can be estimated as:u c is the combined uncertainty (at a confidence level of 68%), s r is the repeatability standard deviation, n is the number of replicates performed for the measurement, s d is the between‐day standard deviation, d is the number of days, over which the n replicates are spread and u t is the uncertainty of the recovery or trueness determination (Linsinger et al., 2013).…”

Development and Validation of Optical Methods for Zeta Potential Determination of Silica and Polystyrene Particles in Aqueous Suspensions

“…In supporting the implementation of legislation, significant advances have been made in the development and validation of new and existing methods for size analysis of (nano)particles [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. As the nano-specific provisions in legislation carry a strong link to “particle size”, there has been less pressure on the validation of methods for the characterization of nanomaterial properties other than particle size so far.…”