IEC 62321-7-1:2015 describes a boiling water extraction procedure intended to provide a qualitative determination of the presence of hexavalent chromium (Cr(VI)) in colourless and coloured corrosion-protection coatings on metallic samples. In this procedure, when Cr(VI) in a sample is detected below the 0,10 g/cm2 LOQ (limit of quantification), the sample is considered to be negative for Cr(VI). Since Cr(VI) may not be uniformly distributed in the coating even within the same sample batch, a "grey zone" between 0,10 g/cm2 and 0,13 g/cm2 has been established as "inconclusive" to reduce inconsistent results due to unavoidable coating variations. In this case, additional testing may be necessary to confirm the presence of Cr(VI). When Cr(VI) is detected above 0,13 g/cm2, the sample is considered to be positive for the presence of Cr(VI) in the coating layer.
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