Validation of the draft community reference method for the determination of solvent yellow 124 in gas oil (Euromarker)

12 batches of samples containing various levels of solvent yellow 124 were prepared. The samples were sent to 26 different laboratories in order to validate the new Community Reference Method for the determinallon of Solvent Yellow 124 (Euromarker) in gas oil. The interlaboratory trial was evaluated according to ISO 5725 and ISO 4259 for determination at 410 and 450 nm. After removal of outliers, repeatability and reproducibility standard deviations were calculated. At the level of 0.12 mg/L the repeatability standard deviation and the between laboratory standard deviation are of the same order. Reproducibility standard deviation at 0.12 mg/L is in the order predicted by the Horwitz equation (0.021 mg/L). The reproducibility standard deviation at 6 mg/L (batch 2) was with 0.23 mg/L better than the 0.4 mg/L that was thought to be achievable. Based on these standard deviations, limits for exceeding the specifications of 6 and 9 mg/L were calculated to be < 5.6 and > 9.5 mg/L respectively.