Work Item
ASTM WK98177

New Test Method for Determination of Total Nitrogen by Alkaline Persulfate Digestion and Colorimetry

1. Scope

This method determines total nitrogen, and TKN by calculation, after a heated alkaline persulfate digestion. Nitrogen compounds are converted to nitrate ions. The nitrate ions react in acidic solution with 2,6-dimethylphenol to form a nitrophenol compound which is read at maximum absorption by a photometer or spectrophotometer.

Keywords

environmental nutrients, test kit, sTKN,

Rationale

THis method is based on the HACH sTKN method that is approved at 40 CFR Part 136, however, the HACH method is approved only for TKN. The method anticipates future EPA approval of TN and this provides users with a VCSB alternative that can use any test kits.

The title and scope are in draft form and are under development within this ASTM Committee.

Details

Developed by Subcommittee: D19.05

Committee: D19

Staff Manager: James Morgan

Work Item Status

Date Initiated: 02-19-2026

Technical Contact: William Lipps