Kjeldahl Nitrogen, Total (TKN) - WS

Grouped product items
SKU Pack Size Availability Price Quantity
Request a Bulk Order Check Availability


applications environmental
concentration in water
Description Kjeldahl Nitrogen, Total (TKN) - WS Proficiency Testing Material
format matrix material
MDM Code PE1575-2ML
Material Number PE1575
Business Unit 533
Shipping Mode AP
Local HS Code 38220090
Legacy SIGMA
Shelf Life 0
Plant 6311
Sales Org 6304
EUD Documents Needed 0



Kjeldahl Nitrogen, Total (TKN) is a parameter for evaluating the quality of water and environmental contamination specifically in water samples. Our product, Kjeldahl Nitrogen, Total (TKN) - Water Supply (WS) is a proficiency testing material used for the determination of total Kjeldahl nitrogen (TKN) and/or organic nitrogen in drinking water samples.

Have any questions? Explore our FAQs.
For more information on this product, please contact our Technical Service team. 

Features and Benefits

We have a vast portfolio of environmental PT schemes with \fit-for-purpose\ samples to help you meet the needs of the laboratory.

Our proficiency testing (PT) program is a benchmark to:

  • provide staff with an insight into their laboratory′s performance, to verify the accuracy and reliability of their testing process
  • provide a comparison of performance with that of other laboratories, nationally and internationally
  • test and educate staff, provide a better understanding of the impact of incorrect results and identify areas where there may be problems
  • provide an independent evaluation of laboratory performance
  • demonstrate to clients, colleagues and accreditation bodies that there is a commitment to quality

General description

Kjeldahl Nitrogen, Total (TKN) - Water Supply (WS), proficiency testing material is produced in accordance with ISO/IEC 17043:2010. Also referred to as Potable Water or Water Supply sample, this sample is manufactured according to TNI requirements. However, please note, this sample may include non-TNI analytes as well. The lower criteria from the TNI tables mimic the levels common to drinking water samples.

Supelco® is a global proficiency testing (PT) provider that manufactures best-in-class environmental and pharmaceutical PT products. The PT portfolio allows our test components to offer significant performance data to monitor and prove competency to customers, accreditation bodies or both.
These samples (WS Concentrates) are typically provided in duplicate for use in case of lab mishap, for QC purposes or to analyze multiple methods.

Type of PT Scheme: Water analysis - Water Supply (WS)

Matrix: Water Supply/Drinking Water

Values of analytes vary from lot to lot.

All information regarding the use of the Kjeldahl Nitrogen, Total (TKN) - Water Supply (WS) can be found in the reporting packet which will be available to download at PT Portal.

Other Notes

Are you new to Supelco® Proficiency Testing? Be sure to register your account details in the PT Portal before placing your order.
This will provide access to data entry, reporting packets and final reports. Registrations will be approved shortly after your order is placed. For further questions, write to us at

When placing your order online, please indicate your study preference under the ′your reference′ column. Available studies can be viewed at the bottom of the page.
Click here to learn more about Quick-Turn Studies (on-demand proficiency tests that are offered depending on lot availability). The Quick-Turn results are released within 48-72 hours whereas scheduled study reports are released within 21 days.

Proficiency testing samples are presented as single blind. No values for the samples are released until the testing period concludes.

Proficiency Testing Schedule (2021-2022)

Drinking Water
WS21-2March 24 - May 7, 2021
WS21-4 September 22 - November 5, 2021

WS22-2March 23 - May 6, 2022
WS22-4 September 21 - November 4, 2022

Preparation Note

Preparation Note
  • PT sample is as a 2 mL concentrate.
  • The solvent for this sample is water.
  • The PT sample has been autoclaved for preservation.

Sample preparation
  • To prepare the solution, partially fill a 1000-mL volumetric flask with ammonia-free, reagent-grade water (near 20 °C).
  • Open ampule PE1575-2ML (be careful to avoid cuts on glass) and transfer 1.0 mL of concentrate to the volumetric flask.
  • Fill the volumetric flask to volume with reagent-grade water and mix well.
  • The sample is now ready for immediate analysis.
  • If a solution is not to be analyzed within two days after preparation, preserve a sample aliquot with 0.2 mL of concentrated sulfuric acid per 100 mL of sample (pH<2) and store at 4 °C until just before analysis. Analyze the preserved sample as soon as possible within the maximum 28-day holding time.

Storage and Stability

Please refer to sample label for expiration date, specific storage temperature, and specific storage conditions.


Signal Word


WGK Germany


Flash Point (F)

Not applicable

Flash Point (C)

Not applicable

Target Organs

Risk Statement

Supplemental Hazard Statements


Certificate of Analysis View Sample COA
Certificate of Origin


Our team of scientists has experience in all areas of research including Life Science, Material Science, Chemical Synthesis, Chromatography, Analytical and many others.

Welcome to Merck Ecommerce (Beta). During this Beta phase, you may encounter occasional broken function, layout and issues. ×