The present archive holds the entire raw data of the weathering protocol inter-laboratory testing group. The group focused on a protocol to identify and quantify the primary release induced by weathering, and assess reproducibility, transferability, and sensitivity towards different materials and uses. We prepared 132 specimens of two polymer-MWCNT composites containing the same grade of MWCNTs used in earlier OECD hazard assessments but without UV stabilizer. This dataset was evaluated, summarized and published in open access (Wohlleben et al 2017).

The pilot inter-laboratory comparison (ILC) included four labs (two US and two EU) aging by UV and rain, then shipping for analysis. Two labs (one US and one EU) conducted the release sampling and analysis by Transmission Electron Microscopy (TEM), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Ultraviolet-Visible Spectroscopy (UVVis), Analytical Ultracentrifugation (AUC), and Asymmetric Flow Field Flow Fractionation (AF4). The report (Wohlleben et al 2017) compares results between aging labs, between analysis labs and between materials, and found: quantitative agreement between analysis labs for TEM, ICP-MS, UVVis; low variation between aging labs by all methods; consistent rankings of release between TEM, ICP-MS, UVVis, AUC. Significant disagreement was related primarily to differences in aging, but even these cases remained within a factor of two.

As a result, the report proposed MWCNT-epoxy without UV stabilizer as a positive control for future laboratory validation, and MWCNT-PA without UV stabilizer as a low-release control. Control data is accessible in the present repository.

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