1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-24318-0 SANS 5210:2010Edition 2.3SOUTH AFRICAN NATIONAL STANDARD Water Nitrate and nitrite content Published by SABS Standards Division 1
4、Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 5210:2010 Edition 2.3 Table of changes Change No. Date Scope Amdt 1 2004 Amended to change the designation of SABS standards to SANS standards and to update referenced standard
5、s. Amdt 2 2006 Amended to update a referenced standard. Amdt 3 2010 Amended to update referenced standards, and to correct values for total oxidized nitrogen in the table in 6.2. Foreword This South African standard was approved by National Committee SABS SC 147A, Water Water sampling and analysis,
6、in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in April 2010. This document supersedes SANS 5210:2006 (edition 2.2). A vertical line in the margin shows where the text has been technically modified by ame
7、ndment No. 3. SANS 5210:2010 Edition 2.3 1 Water Nitrate and nitrite content 1 Scope and field of application This standard specifies a method of measuring the concentration of nitrate and nitrite nitrogen in water and in wastewater. The method is conveniently applied after the determination of free
8、 and saline ammonia, using SANS 5217, since the residue in the distillation flask after the performance of SANS 5217 can be used as the test portion to be reduced with Devardas alloy. Nitrite nitrogen should be determined separately by using SANS 6777 if the concentrations of both nitrate and nitrit
9、e nitrogen are required. Amdt 2 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) app
10、lies. Information on currently valid national and international standards can be obtained from the SABS Standards Division. Amdt 1 SANS 111/ISO 835, Laboratory glassware Graduated pipettes. Amdt 1; amdt 3 SANS 112/ISO 648, Laboratory glassware Single volume pipettes. Amdt 1 SANS 115/ISO 385, Laborat
11、ory glassware Burettes. Amdt 1; amdt 3 SANS 128/ISO 1042, Laboratory glassware One-mark volumetric flasks. Amdt 1 SANS 3696/ISO 3696, Water for analytical laboratory use Specification and test methods. SANS 5217, Water Free and saline ammonia content. SANS 5219, Nitrite content of water. Amdt 2 SANS
12、 6777/ISO 6777, Water quality Determination of nitrite Molecular absorption spectrometric method. Amdt 2 SANS 5210:2010 Edition 2.3 2 3 Principle After the removal of ammonical nitrogen from the test portion by distillation under alkaline conditions, the nitrate and nitrite are reduced with Devardas
13、 alloy, resulting in a quantitative conversion to ammonia that is distilled over with the distillate into a boric acid solution where an equivalent amount of borate is produced. The borate is titrated with a standard acid solution to the equivalence point, which is detected with a mixed indicator. 4
14、 Reagents NOTE Unless otherwise specified, only use water that complies with the requirements of SANS 3696 and reagents of analytical reagent grade. 4.1 The reagents listed in SANS 5217. 4.2 Devardas alloy (an alloy of 50 % copper (Cu), 45 % aluminium (AI), and 5 % zinc (Zn), and containing less tha
15、n 0,005 %(m/m) nitrogen (N). 4.3 Nesslers reagent. 5 Apparatus 5.1 The apparatus listed in SANS 5217. 5.2 Glassware. Where applicable, only use burettes, pipettes and volumetric flasks that comply with the requirements for class A items as specified in SANS 111, SANS 112, SANS 115 and SANS 128, as r
16、elevant. Amdt 1; amdt 3 6 Procedure NOTE Unless otherwise specified, only use water that complies with the requirements of SANS 3696. 6.1 If free and saline ammonia has been determined using SANS 5217, proceed to 6.9. 6.2 Select a suitable volume of sample, using the following table as a guide: 1 2
17、Total oxidized nitrogen Sample size as N in mg/L mL 0 1 500 2 10 250 11 20 100 21 50 50,0 51 100 25,0 Amdt 3 NOTE The sample size shown above is an estimate made on the basis of a titration using the standard sulfuric acid (H2SO4) solution c(1/2 H2SO4) = 0,02 mol/L. 6.3 Transfer the aliquot to a dis
18、tillation flask and dilute the sample to approximately 500 mL with water. SANS 5210:2010 Edition 2.3 3 6.4 Add 5-6 drops of the bromothymol blue indicator solution and adjust the pH to a value in the range pH 6,0 (indicator yellow) to pH 7,4 (indicator blue), using either the sodium hydroxide (NaOH)
19、 solution or the sulfuric acid (H2SO4) solution, as appropriate. 6.5 Add 0,3 g of light magnesium oxide, mix and add some anti-bump beads. 6.6 Attach the distillation flask to the anti-splash head and connect to the condenser. 6.7 Distil vigorously until 275 mL 25 mL of distillate has been collected
20、 in a receiving flask. 6.8 Check the last few distillate volumes of 15 mL 5 mL with Nesslers reagent (see 4.3) to ensure that all ammonia has been distilled over, and discard the distillate. 6.9 Allow the residue in the flask to cool. 6.10 Dilute to approximately 500 mL, add 1 g of Devardas alloy (s
21、ee 4.2) and mix. 6.11 Attach the distillation flask to the anti-splash head and connect to the condenser. 6.12 Immerse the condenser outlet in 50 mL of the boric acid/indicator solution in a receiving flask. 6.13 Boil the mixture gently for approximately 5 min to avoid excessive frothing, and then b
22、oil vigorously until 250 mL to 300 mL of distillate has been collected. 6.14 Titrate the distillate in the boric acid/indicator solution to the purple end-point, using the standard H2SO4volumetric solution, c(1/2 H2SO4) = 0,02 mol/L. NOTE The standard H2SO4volumetric solution, c(1/2 H2SO4) = 0,10 mo
23、l/L, may be used for titration of distillates from samples having high nitrate/nitrite contents. 6.15 Always carry a blank through the whole procedure, substituting water for the sample. 7 Expression of results The nitrate and nitrite content, expressed as nitrogen (N) in mg/L, is given by the formu
24、la 021000114,01)(VcVV where V0is the volume of the test portion, in millilitres; V1is the volume of sulfuric acid solution used in titration of the sample distillate, in millilitres; V2is the volume of sulfuric acid solution used in titration of the blank distillate, in millilitres; c is the exact c
25、oncentration of the sulfuric acid used in the titration, c(1/2 H2SO4), in moles per litre. SABS This page has been left blank intentionally SABS Standards Division The objective of the SABS Standards Division is to develop, promote and maintain South African National Standards. This objective is inc
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