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Announcement for Inter-laboratory Comparison on Arsenic and Ammonia Nitrogen in Water 2022
Update time: 2022-08-02
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We hereby announce the 4th Inter-laboratory Comparison on Water Quality Analysis, which is focused on the Proficiency Testing of Arsenic and Ammonia Nitrogen in Water. This activity is open to academic, regulatory as well as commercial laboratories world-wide, especially those from developing and emerging countries. The organizers of this project are CAS-TWAS Centre of Excellence for Water and Environment (CAS-TWAS CEWE) and Water Quality Analysis Laboratory, which both are established at the Research Center for Eco-Environmental Sciences (RCEES), Chinese Academy of Sciences (CAS). This project is supported by the Certification and Accreditation Administration of the People’s Republic of China (CNCA) and the Alliance of International Science Organizations (ANSO).

A draft report will be available at the end of February 2023, and the final report will be available to the participants by March 2023. All the participants who have contributed to the results will receive a certificate of participation in the activity.



We encourage all laboratories working in this field to participate and assess their analytical performance. To do this, participants are requested to completely fill out the Registration Form and mark the desired samples that you intend to determine.


Test Samples

The test samples for Arsenic are in concentrations of 75.0-250μg/L with 1% nitric acid as matrix.


The test samples for Ammonia Nitrogen are in concentrations of 2.50-25.0mg/L with H2O as matrix.


The samples will be distributed by an international courier service to the participating laboratories.


Please Note:

In order to avoid delay or retention of the samples at customs, please inform us if there are import restrictions in your country for any of the samples.


Instructions for analysis and reporting

Further detailed instructions and reporting forms will be sent by e-mail simultaneously with the dispatch of the samples in October  2022.


In short, the participating laboratories should:

·        use your own standard operation procedures for pre-treatment and instrumental determination

·         use your own reference standards for identification and quantification

·         report one single concentration for each testing sample in each water matrix

·         report limits of determination for all measured analytes


Time Schedule



August 1st, 2022

Return of registration form

September 30th, 2022

Shipment of test material

October 2022

Confirmation of receipt of test material by participant

Within 7 days after receipt

Reporting of test results

Within 30 days after receipt

Publication of draft report on web-site

February 2023

Final report available to all participants

March 2023


Participation Fee

The participation fee for any combination of the analytes in one item is free.


All recipients of this invitation are sincerely welcome to participate in the Inter-laboratory Comparison, and are encouraged to spread the activity to possibly interested laboratories!


Co-ordinating Group


SI Ludan


Phone: +86 10 62849800





Phone: +86 10 62849466


E-mail Address

For all enquiries by e-mail, please use cas_twas@rcees.ac.cn.


Postal Address:

Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences

18# ShuangQing Road, Haidian District, Beijing, P.R.China, 100085

Copyright 2007-2014 RCEES/CAS, All Rights Reserved.
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People’s Republic of China