Certified values1 uncertainty2

Total Hg .................................................. 132 mg/kg ..................... 3 mg/kg

CH3Hg+ ................................................... 0.0755 mg/kg ................. 4 µg/kg

1) Unweighted mean value of the means of 11 to 13 accepted sets of data, each set being obtained in a different laboratory and / or with a different method of determination. Certified value is based on dry mass. The certified values are traceable to SI.

2) The certified uncertainty is the half-width of the 95 % confidence interval of the mean defined in 1). k-factors were chosen according to the t-distribution depending of the number of accepted sets of results and were 2.179 for total Hg and 2.228 for MeHg.