Estimation of measurement uncertainty of coliforms in drinking water according to ISO19036:2019
[Objective]This study aimed to estimate the measurement uncertainty of coliforms in drinking water according to ISO19036:2019.[Methods]By designing protocols,the technical uncertainty(utech),matrix uncertainty(umatrix)and distribution uncertainty(udistrib)were estimated respectively,and the combined uncertainty(uc(y))and extended uncertainty(U)were calculated by combining the values of the three components.[Results]After estimating the measurement uncertainty of the second method of GB 4789.3-2016,the technical uncertainty was 0.120 2 log(CFU/mL),the matrix uncertainty was 0.1 log(CFU/mL),and the distribution uncertainty was 0.065 5 log(CFU/mL)and 0.026 1 log(CFU/mL).When the result was 440 CFU/mL,the extended uncertainty was 0.34 log(CFU/mL),expressed as(2.64±0.34)log(CFU/mL).[Conclusion]According to ISO19036:2019,the estimation of measurement uncertainty for quantitative determinations of microorganisms in food is more scientific and convenient compared to current domestic standards.
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