Report of the Inter-laboratory Comparison on Manganese and Permanganate Index in Water II (2020)

This work was the second part of the Inter-laboratory Comparison on Manganese and Permanganate Index in Water (2020), which was jointly conducted by Water Quality Analysis Laboratory, RCEES, CAS and Centre of Excellence for Water and Environment (CEWE), CAS-TWAS. And as part II of this activity, we sinceryly appreciated the support from both Certification and Accreditation Administration of People’s Republic of China, CNCA and RusAccreditation.

This study also included the determination of manganese and permanganate index in two different water items, which were both distributed to the participating laboratories with two testing samples at the same concentration respectively. Based on the close cooperation between China and Russia in the field of the inspection and testing industry, 9 representative laboratories were recommened by RusAccreditation to participate this project.

Totally 13 sets of testing samples were sent to the 9 different laboratories. This report II presents the returned results for 9 sets of manganese samples and 4 sets of permanganate index samples. 

The standard value for each analyte in the testing samples were determined by National Institute of Metrology, China. All values exceeding ±50% of the assigned concentrations were removed from the calculation. The consensus mean and the standard deviation (SD) were calculated from the remaining data, while this SD and the consensus mean were used to subsequently calculate z-scores.

For the samples of manganese-a and -b, z-scores within ±2 were obtained by 66.7% of the reporting participants (corresponding to 6 of the total 9 participants) .

For the samples of permanganate index-a and -b, within ±2 were obtained by 75% of the reporting participants (corresponding to 3 of the total 4 participants) .

Inter-laboratory Comparison is an effective way to improve the quality control system for the analytical laboratories through external measures, which is particularly becoming of increasing importance in the context of globalization of world economy. 

The main objective of the activity is to assess the between laboratory reproducibility on water quality analysis, and to provide a QA/QC tool for each participating laboratory to improve their performance.

The second part of this activity started from November 2020. And because of the Customs inspection when delievering samples, 8 sets of samples were distributed to the 5 laboratories again in January 2021. Therefore, The work of this part was ended in March 2021 when all the result reports were received. And the report was drafted on April 2021.

From the end of 2019, the worldwide SARS-CoV-2 epidemic had brought great challenges to the implementation of this inter-laboratory comparison work. We sincerely appreciate all the participants and individual analysts for their professional contribution to to this activity.

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