Uncertainty evaluation for the determination of cypermethrin residue in landscape soil
The evaluationof uncertainty is of great importance for improving detection methods and quantitatively characteri-zing the quality of determination results.In this study,a method based on dispersive solid phase extraction(d-SPE)and gas chromatography(GC)was utilized to quantify cypermethrin residue in landscape soil.The key sources of uncertainty in the measurement process were evaluated,including repeated determination of samples,standard solution preparation,fitness of standard curve,sample weighing and pretreatment,recovery rate,and the measurement of GC.Each uncertainty component was quantified and subsequently combined and expanded following the law of propagation of uncertainty.The results showed that when landscape soil was spiked with cypermethrin at a concentration level of 0.10 mg/kg,the relative standard uncer-tainty of each component were 7.03×10-3,3.00×10-2,1.63×10-2,8.17×10-3,1.12×10-2,1.32×10-2and 8.66×10-3,re-spectively.The relative combined standard uncertainty was calculated to be 9.72×10-3,and the expanded uncertainty was determined to be 0.001 8 mg/kg.The determination results of cypermethrin in landscape soil in 95%confidence interval could be expressed as(0.090±0.001 8)mg/kg(k=2).Based on uncertainty evaluation,the main sources of uncertainty came from standard solution preparation,standard curve fitting and recovery rate,indicating that these aspects should be controlled strictly in the following sample analysis.The findings could provide a valuable reference for improving and assess-ing the accuracy of the d-SPE-GC method for the determination of cypermethrin residue in landscape soil.
Gas chromatographyLandscape soilCypermethrinUncertaintyAnalysis
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