Round Robin Test on Microplastic Counting and Identification Method

The aim of this work is to verify the quality, robustness, and accuracy of a standard analytical protocol for the determination of microplastics in aqueous textile matrices. In order to reach this objective, a round robin scale identification and quantification test program was conducted. In particular, this chapter describes the round robin test, an interlaboratory comparison test on standard microfilament suspensions initiated in November 2021 by an expression of interest open call. In total, 18 laboratories expressed their interest, and 13 participants sent their results. Each of these laboratories received a set of 10 samples, accompanied by a protocol. The 10 samples consisted of three replicates per type of three different synthetic yarns and a control sample. The data required were the number of microplastics per sample recognized as fibers or particles, microplastic fiber lengths and diameters, and identification of the polymer using vibrational spectroscopy (μ-FTIR and/or μ-Raman). The data collected were statistically elaborated. The results highlighted that the laboratories had different recovery rates directly related to their specific procedures and equipment. Although there were issues related to the correct use of the standard method and to the behavior of operators, the method proved to be valid for the determination of microplastics in aqueous matrices.