ATP Validation of COD Tests by MACHEREY-NAGEL – Experience Report on the Use of the New EPA Procedure for Method Defined Parameters

Oral Presentation

Prepared by C. Prokisch
MACHEREY-NAGEL, Neumann-Neander-Strasse 6-8, Dueren, NRW, 52355, Germany


Contact Information: cprokisch@mn-net.com; +4924219690


ABSTRACT

In February 2016 the EPA published an update of the ATP protocol with an Appendix targeting the validation of Method Defined Parameters (MDP). To our knowledge, we were the first to use this process in our approach to get approval for COD tests.
The term “Method Defined Parameter” means an analyte that is defined solely by the method used to determine the analyte. In our case, COD is everything that can be oxidized by Dichromate under the specified conditions. There is no “true” COD. Therefore, a specific approach is necessary to ensure, that COD tests of different origin provide statistically indistinguishable results.
In the first stage, a side-by-side comparison between MACHEREY-NAGEL COD tests and the EPA approved HACH method 8000 on 9 different matrices was used to provide the necessary evidence. The challenges and the caluclations will be described in detail in the presentation. In the second stage, results from 9 different labs were used to establish the QC acceptance criteria for the method.
MACHEREY-NAGEL is a German company founded in 1911 that is the major competitor of HACH in Germany and large parts of Europe. This competition led to a comparably very modern installation base for instruments that provides huge benefits for the end-user. In the US, MACHEREY-NAGEL water analysis has so far not been available.