. Author manuscript; available in PMC: 2020 Sep 1.

Published in final edited form as: Int J Hyg Environ Health. 2019 Jul 18;222(8):1059–1067. doi: 10.1016/j.ijheh.2019.07.005

Table 1.

Summary of the analytical procedures employed in the laboratories that participated in the round-robin trial.

	France	Germany	Japan
Sample preparation	Samples (300 μl) were transferred into a 13-ml polypropylene tube and mixed with 2,700 μl dilution solution. Dilution solution was made by adding 10 ml 25% NH4OH, 250 mg EDTA dipotassium salt and 250 μl Triton X-100 into a volumetric flask and filled up to 500 ml with double distilled water.	Samples (300 μl) were transferred into a 13-ml polypropylene tube and mixed with 2,700 μl dilution solution. Dilution solution was made by adding 10 ml 25% NH4OH, 250 mg EDTA dipotassium salt and 250 μl Triton X-100 into a volumetric flask and filled up to 500 ml with double distilled water.	Samples (200 μl) were diluted (1:19) with the dilution solution and vortex mixed. Dilution solution consisted of 2% v/v butan-1-ol, 0.1% TMAH, 0.5 g l⁻¹ POE and 0.5 g l⁻¹ H₄EDTA
Instrumental analysis	ICP-MS (Agilent 7500) with ASX 500 auto-sampler	ICP-DRC-MS (Agilent 7500cx) with ASX 500 auto-sampler	ICP-MS (Agilent 7700 ICP-MS) with auto-sampler
Calibration and calculation	External calibration was used. The limit of quantitation was 0.15 μg l⁻¹.	External calibration was used. The limit of quantitation was 0.15 μg l⁻¹.	External calibration was used. The limit of quantitation was 0.14 μg l⁻¹.