Uncertainty of Determination of Methyl Parathion Residues in Vegetables by Gas Chromatography
According to the"Evaluation and Expression of Measurement Uncertainty"(JJF 1059.1-2012)and"Determination of Organophosphorus,Organochlorine,Pyrethroid and Amino Ester Pesticide Residues in Vegetables and Fruits"(NY/T 761-2008),a mathematical model is established to evaluate the uncertainty in the determination of methyl parathion residues in vegetables.The main sources of measurement uncertainty are sample quality weighing,volume,working solution preparation,addition and recovery,precision,and the synthesis standard uncertainty and extended uncertainty are calculated.The results indicate that the uncertainty introduced by the preparation of standard stock solution and standard working solution is the key source of uncertainty.The standard uncertainty Uc(W)for the synthesis of methyl parathion is 0.001 82 mg/kg,with a confidence level of 95%.The extended uncertainty U(W)for methyl parathion is 0.003 64 mg/kg.The uncertainty in the determination of residual methyl parathion in vegetables can be expressed as(X±U)=(0.10±0.003 64)mg/kg.
gas chromatography methodvegetablemethyl parathionuncertaintyevaluate
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