On the precision of particle size analysis by micro-thermal field-flow fractionation

Abstract

Micro-Thermal Field-Flow Fractionation of polymer colloidal particles was performed in two different laboratories. Short term repeatability of the experimental retentions obtained in a single laboratory has been found to be very high. The short term precision (expressed as percent standard deviation) of the determination of average particle diameter can reach the values greater than 1%, relative. Average repeatability of the retentions in both laboratories was better than 3%, relative when using identical experimental protocol. No other method of particle size analysis can provide the results of a comparable precision. Average repeatability of the width of the raw fractograms, which contains the information on particle size distribution, is of the order of 5%, relative. However, this value cannot be considered as the ultimate limit because the experiments were not carried at the low flow rate of the carrier liquid permitted to reach much higher resolution. The effect of the stability of the most important operational variables, such as the temperature drop between the cold and hot walls, the temperature of the cold wall, and the flow rate of the carrier liquid, on the precision of the analytical results is discussed.