Description_x000D_ General description_x000D_ This proficiency testing sample is produced in accordance with ISO/IEC 17043:2010. All information regarding the use of this material can be found in the reporting packet supplied for each sample._x000D_ Other Notes_x000D_ Proficiency testing samples are presented as single blind. No values for the samples are released until the testing period concludes. Values of analytes vary lot to lot._x000D_ Proficiency Testing Schedule (2020-2021)_x000D_ Drinking Water_x000D_ WS20-1 January 15 - February 28, 2020_x000D_ WS20-2 March 25 - May 8, 2020_x000D_ WS20-3 July 8 - August 21, 2020_x000D_ WS20-4 September 23 - November 6, 2020_x000D_ WS21-1 January 13 - February 26, 2021_x000D_ WS21-2 March 24 - May 7, 2021_x000D_ WS21-3 July 7 - August 20, 2021_x000D_ WS21-4 September 22 - November 5, 2021_x000D_ Quick-Turn Study - (non-scheduled proficiency test that is available at any time)