SOUTH AFRICAN NATIONAL STANDARD

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1 ISBN SOUTH AFRICAN NATIONAL STANDARD Water Albuminoid ammonia content WARNING Can only be used in conjunction with SANS Published by Standards South Africa 1 dr lategan road groenkloof private bag x191 pretoria 0001 tel: fax: international code Standards South Africa

2 Table of changes Change No. Date Scope Foreword This South African standard was approved by National Committee StanSA SC A, Water Water sampling and analysis, in accordance with procedures of Standards South Africa, in compliance with annex 3 of the WTO/TBT agreement. This standard was published in February This edition cancels and replaces the first edition (SABS SM 218:1971).

3 Water Albuminoid ammonia content 1 Scope This standard specifies a method for the determination of the albuminoid ammonia content of water after the liberation of the free and saline ammonia in accordance with SANS NOTE Albuminoid ammonia is that portion of nitrogen in a given volume of water which can be obtained from the undecomposed organic substance after the free and saline ammonia have been determined. 2 Normative references The following referenced documents are indispensable for the application of this document. All normative documents are subject to revision and, since any reference to a normative document is deemed to be a reference to the latest edition of that document, parties to agreements based on this document are encouraged to take steps to ensure the use of the most recent editions of the normative documents indicated below. Information on currently valid national and international standards can be obtained from Standards South Africa. SANS 3696/ISO 3696, Water for analytical laboratory use Specification and test methods. SANS 5217, Water Free and saline ammonia content. 3 Principle After the liberation of the free and saline ammonia (see SANS 5217) the albuminoid ammonia is liberated by the action of alkaline permanganate solution on the nitrogenous matter present. 4 Reagents 4.1 General Unless otherwise specified, only use water that complies with the requirements for grade 3 water as given in SANS 3696, and reagents of analytical reagent grade. 4.2 Alkaline potassium permanganate solutions Alkaline solution Dissolve either 364 g of potassium nitrate (KNO 3 ) or 144 g of sodium hydroxide (NaOH) in 400 ml of water to make up a 9 M alkaline solution. WARNING Heat is generated during the dissolution of NaOH in water, and appropriate care should be taken such as wearing goggles. 1

4 4.2.2 Stock solution Dissolve 8,0 g of potassium permanganate in approximately 400 ml of water, and transfer to a 1 L volumetric flask. Add 400 ml of a clear 9 M solution of potassium hydroxide (see 4.2.1) or sodium hydroxide (see 4.2.1). Make up to the mark with distilled water, and mix Working solution During the distillation of free and saline ammonia (see SANS 5217), place 50 ml of the stock solution in a nickel basin. Dilute with 50 ml of distilled water and concentrate by boiling to a volume of 50 ml. Allow to cool slightly before adding to the distillation flask (see clause 6). 4.3 Standard ammonium chloride solution Dissolve 3,821 g of ammonium chloride in water in a 1 L volumetric flask. Dilute to the mark with water, and mix. When required for use, dilute 1,0 ml of this solution to 100 ml with water in a volumetric flask (1 ml 0,01 mg of nitrogen). 4.4 Nessler reagent Dissolve 45,5 g of mercuric iodide and 34,9 g of potassium iodide in a minimum volume of water. Add 112 g of potassium hydroxide, and dilute the mixture to 1 L with water. Allow to stand for 48 h and use the clear supernatant liquid. 5 Apparatus 5.1 Basin, of nickel. 5.2 Volumetric flasks, of capacity 250 ml and 1 L. 5.3 Distillation flask. 5.4 Nessler tubes, set of 50 ml. 6 Procedure 6.1 Add 50 ml of the warm working solution of alkaline potassium permanganate (see 4.2.3) to approximately 200 ml to 250 ml of boiling liquid retained in the distillation flask (see SANS 5217). Continue distillation at a rate of 8 ml to 13 ml, per minute. Collect the distillate in a 250 ml volumetric flask and continue the distillation until about 245 ml of the distillate has been collected. Dilute with water to the 250 ml mark and mix. 6.2 Add suitable volumes (0,3 ml to 3,0 ml) of the standard ammonium chloride solution to a series of 50 ml Nessler tubes containing some water. To another Nessler tube add a suitable aliquot of the distillate. 6.3 Add 2 ml of the Nessler reagent to each tube and dilute to the mark with water. Mix, and allow to stand for 10 min. By colour-matching select the standard solution which matches the distillate solution most closely. 2

5 7 Calculation Calculate the albuminoid ammonia concentration, N, of the sample taken, expressed in milligrams per litre, as follows: where N = A 10 B A B is the volume of standard ammonium chloride used in a matching tube, in millilitres; is the volume of the aliquot of the distillate, in millilitres. Standards South Africa 3

SOUTH AFRICAN NATIONAL STANDARD

ISBN 978-0-626-33085-9 SOUTH AFRICAN NATIONAL STANDARD Water Free and saline ammonia content Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001 Tel: +27 12