Significance and Use

These test methods are useful for measuring organic nitrogen and ammoniacal nitrogen, which are essential growth nutrients.

Nitrogen compounds are widely distributed in the environment. Sources of nitrogen include surface-applied fertilizers, cleaning products, and drinking water treatment aids. Because nitrogen is a nutrient for photosynthetic organisms, it may be important to monitor and control discharge into the environment.

1. Scope

1.1 These test methods cover the determination of total Kjeldahl nitrogen. The following test methods are included:

1.2 The analyst should be aware that precision and bias statements included may not necessarily apply to the water being tested.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

8.1 This test method covers the determination of total Kjeldahl nitrogen in water. It measures free ammonia or ammonia formed from the conversion of nitrogen components of biological origin such as amino acids and proteins. However, the procedure may not convert the nitrogenous compounds of some wastes to ammonia. Examples of such compounds that may not be measured are nitro compounds, hydrozones, oximes, nitrates, semicarbazones, pyridines, and some refractory tertiary amines.

8.2 Three alternatives are described for the final determination of the ammonia: a titrimetric method, which is applicable to concentrations above 1 mg N/L; a Nesslerization method, which is applicable to concentrations below 1 mg N/L; and a potentiometric method which is applicable to the range from 0.04 to 1000 mg N/L.

8.3 This test method is described for micro and macro systems. Micro determination can be made on sample aliquots containing up to 10 mg of nitrogen.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

D1129 Terminology Relating to Water

D1193 Specification for Reagent Water

D1426 Test Methods for Ammonia Nitrogen In Water

D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water

D3370 Practices for Sampling Water from Closed Conduits

D5810 Guide for Spiking into Aqueous Samples

D5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis

Keywords

analysis; colorimetric; distillation; TKN; water; Bertholt method; Brackish water/brines; Colorimetric analysis--water; Distillation; Inorganic compounds--water; Kjeldahl method; Manual digestion method; Organic compounds--water; Nitrogen content--water; Semi-automated methods; TKN;

ICS Code

ICS Number Code 13.060.50 (Examination of water for chemical substances)

DOI: 10.1520/D3590-11

ASTM International is a member of CrossRef.

ASTM D3590