The Inter-laboratory Comparison on Iron and Fluoride in Water (2021) was jointly implemented by Water Quality Analysis Laboratory, RCEES, CAS and Centre of Excellence for Water and Environment (CEWE), CAS-TWAS in 2021. This activity was supported by the Certification and Accreditation Administration of the People’s Republic of China, CNCA (Approved as CNCA [2021] 25) and the Alliance of International Science Organizations (ANSO-CR-KP-2020-05).

This study included determining iron and fluoride 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 reproducibility of inter-laboratory.

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

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

Eighty-four testing samples were sent to 22 different laboratories from 12 countries. Because of the ongoing epidemic prevention and control, 29 sets of data, including 16 sets for iron and 13 sets for fluoride, have been returned from 18 laboratories of 9 countries.

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

For the iron samples (-a and -b), z-scores within ±2 were obtained by 81.2% of the reporting participants (corresponding to 13 of the total 16 participants).

For the fluoride samples (-a and -b), z-scores within ±2 were obtained by 84.6% of the reporting participants (corresponding to 11 of the total 13 participants).

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Report of the Inter-laboratory Comparison on Iron and Fluoride Detection in Water (2021).pdf