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_ Preparation Note_x000D_ This PT sample is packaged as a 20mL concentrate._x000D_ The solvent for this sample is water._x000D_ The PT sample is not preserved._x000D_ Sample Preparation_x000D_ Partially fill a 1000mL volumetric flask with reagent-grade water (near 20ºC). NOTE: The dilution volume has changed from previous studies so that the concentration can cover the entire NELAC range._x000D_ Invert ampule PE1081-20ML three times._x000D_ Open the ampule (be careful to avoid cuts on glass) and transfer 10.0 mL of concentrate to the volumetric flask._x000D_ Fill the volumetric flask to volume with reagent-grade water and mix well._x000D_ Calibrate your instrument as directed by the manufacturer._x000D_ Ensure that the solution is thoroughly mixed immediately prior to analysis._x000D_ DO NOT USE a matrix modifier with this sample. The matrix modifier will adversely affect your results._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_ ._x000D_ Proficiency Testing Schedule (2020-2021)_x000D_ Wastewater_x000D_ WP20-1 January 15 - February 28, 2020_x000D_ WP20-2 March 25 - May 8, 2020_x000D_ WP20-3A May 13 - June 26, 2020_x000D_ WP20-3B July 8 - August 21, 2020_x000D_ WP20-4 September 23 - November 6, 2020_x000D_ WP20-5 November 25 - January 8, 2021_x000D_ WP21-1 January 13 - February 26, 2021_x000D_ WP21-2 March 24 - May 7, 2021_x000D_ WP21-3 July 7 - August 20, 2021_x000D_ WP21-4 September 22 - November 5, 2021_x000D_ Quick-Turn Study - (non-scheduled proficiency test that is available at any time)