The interlaboratory programme

The stability of the solutions 1 and 2 was verified on the content of 10 bottles stored at 4°C in the dark over a period of 8 weeks at the National Food Agency. Analyses were performed by packed column gas chromatography followed by electron capture detection. Determinations were performed in 3 replicates on each of 3 bottles. 

The results of this intercomparison on solutions did not reveal any major discrepancies in the final methods of final determination used. The mean of laboratory means was in all cases very close to the value expected upon preparation ((10.1 0.8) mg kg as MeHgCl for solution 1 (12.7 1.2) mg kg as MeHgCl for solution 2 and (2.13 0.26) mg kg as MeHgCl for solution 3, respectively). Table 12.6 lists the coefficient of variation (CV) obtained between laboratories both for solutions 1 and 2, the CVs obtained (8.0 and 8.9% respectively) were considered to be acceptable. In the case of the aqueous solution (solution 3), a CV of 12.3% was found to be too high for the present state of the art. On the basis of these results, it was decided to organise a second intercomparison on fish extracts and to repeat an exercise on aqueous solution. 

RESULTS OF THE THREE INTERCOMPARISONS INCLUDED IN THE IMPROVEMENT SCHEME ON MeHg IN FISH TISSUES 

CV coefTicient of variation (%) between laboratories range ratio higher value versus lower value 

First round Solution 2 — First round Range CV (%) Range 

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