霉菌和酵母计数能力验证结果分析及不确定度评定

Result analysis and uncertainty evaluation of capability verification for mold and yeast

通过参加能力验证,考核实验室的检验能力并优化数据处理能力。按照GB 4789.15—2016的方法开展检测,通过增加平行样数量,严格把控计数时间来提高数据的准确度。根据JJF 1059.1—2012从稀释倍数(样品原液制备、递增稀释)、加样体积、计数结果3方面对不确定度进行评定。结果显示,23-I389检测结果为1000 CFU/mL和23-F825检测结果为190 CFU/mL。2个能力验证样品|Z|值均小于2.0,结果为满意。样品23-I389的不确定度为3.50×10^(-2),样品23-F825的不确定度为3.20×10^(-2)。霉菌和酵母计数能力验证时,由于菌落数量较多,24 h后就要严格把控计数时间,以防菌落蔓延影响计数。单个样本做的平行少时,稀释引入的相对标准不确定度占比最大,因此在实验时,要严格控制实验室温度且要做到准确计量。实验室霉菌和酵母菌计数的检验能力能达到要求。数据处理能力得到了显著的提升。

Verify the laboratory's inspection capabilities and optimize data processing capabilities by participating in competency verification.The test was carried out according to GB 4789.15-2016.The accuracy of data is improved by increasing the number of parallel samples and strictly controlling the counting time.According to JJF 1059.1-2012,the uncertainty was evaluated from dilution ratio(sample stock solution preparation,incremental dilution),adding volume and counting results.The test result for 23-I389 was 1000 CFU/mL and the test result for 23-F825 was 190 CFU/mL.The value of|Z|of the two capability verification samples is lower than 2.0,and the result is satisfactory.The uncertainty of sample 23-I389 is 3.50×10^(-2)and that of sample 23-F825 is 3.20×10^(-2).The counting time should be strictly controlled after 24 hours to prevent the spread of colonies from affecting the count.The standard uncertainty by the dilution of a single sample is the largest proportion,so the laboratory temperature should be strictly controlled and the measurement should be accurate during the experiment.The testing ability of mold and yeast count in this laboratory can meet the requirements.Data processing capacity has been significantly improved.