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

The Inter-laboratory Comparison on Manganese and Permanganate Index in Water (2020) was jointly conducted by Water Quality Analysis Laboratory, RCEES, CAS and Centre of Excellence for Water and Environment (CEWE), CAS-TWAS in 2020. And this activity was supported by Certification and Accreditation Administration of People’s Republic of China, CNCA.

This study 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. The objectives of this proficiency testing were

A. To offer a tool for quality assurance to the participating laboratories.

B. To assess the between laboratory reproducibility.

C. To provide a general overview of the analytical performance of laboratories in the countries along the Belt and Road.

D. To elevate the quality control system of the laboratories in the countries along the Belt and Road.

Thirty-eight testing samples were sent to 26 different laboratories from 12 countries along the Belt and Road, with 15 sets of data returned from 12 laboratories of 9 countries. This report presents the reported results for 10 sets of manganesesamples and 5 sets of permanganate index samples. In additional, one set of manganese samples was retested by one laboratory after discussion and application.

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 70% of the reporting participants (corresponding to 7 of the total 10 participants) . A satisfactory result for the retested samples with an intial problematic result was obtained.

For the samples of permanganate index(-a and -b), z-scores over 3 were obtained by 80% of the reporting participants (corresponding to 4 of the total 5 participants), and the z-score within ±2 and between 2-3 were achieved by the same proportion of 20% of the participants respectively.

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