SIST EN ISO 11905-1:2000

Water quality - Determination of nitrogen - Part 1: Method using oxidative digestion with peroxodisulfate (ISO 11905-1:1997)

This international/European standard specifies a method for the determination of nitrogen present in water, in the form of free ammonia, ammonium, nitrite, nitrate and organic nitrogen compounds capable of conversion to nitrate under the oxidative conditions described. Dissolved nitrogen gas is not determined by this method.

Wasserbeschaffenheit - Bestimmung von Stickstoff - Teil 1: Bestimmung von Stickstoff nach oxidativem Aufschluß mit Peroxodisulfat (ISO 11905-1:1997)

Dieser Teil der ISO 11905 legt ein Verfahren zur Bestimmung von Stickstoff fest, der in Form von freiem Ammoniak, Ammonium, Nitrit, Nitrat und organischen Stickstoffverbindungen in Wässern vorkommt und unter den beschriebenen oxidativen Bedingungen in Nitrat umwandelbar ist. Gelöster gasförmiger Stickstoff wird mit diesem Verfahren nicht erfaßt. Das Verfahren ist geeignet zur Analyse von natürlichem Süßwasser, Meerwasser, Trinkwasser, Oberflächenwasser und behandeltem Abwasser einer Aufbereitungsanlage.

Qualité de l'eau - Dosage de l'azote - Partie 1: Méthode par minéralisation oxydante au peroxodisulfate (ISO 11905-1:1997)

Kakovost vode – Določevanje dušika – 1. del: Metoda z oksidativnim razklopom s peroksidisulfatom (ISO 11905-1:1997)

General Information

• Status: Published
• Publication Date: 31-Dec-1999
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: KAV - Water quality
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Jan-2000
• Due Date: 01-Jan-2000
• Completion Date: 01-Jan-2000
• Ref Project: EN ISO 11905-1:1998 - Water quality - Determination of nitrogen - Part 1: Method using oxidative digestion with peroxodisulfate (ISO 11905-1:1997)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 11905-1:2000
01-januar-2000
.DNRYRVWYRGH±'RORþHYDQMHGXãLND±GHO0HWRGD]RNVLGDWLYQLPUD]NORSRPV
SHURNVLGLVXOIDWRP,62
Water quality - Determination of nitrogen - Part 1: Method using oxidative digestion with
peroxodisulfate (ISO 11905-1:1997)
Wasserbeschaffenheit - Bestimmung von Stickstoff - Teil 1: Bestimmung von Stickstoff
nach oxidativem Aufschluß mit Peroxodisulfat (ISO 11905-1:1997)
Qualité de l'eau - Dosage de l'azote - Partie 1: Méthode par minéralisation oxydante au
peroxodisulfate (ISO 11905-1:1997)
Ta slovenski standard je istoveten z: EN ISO 11905-1:1998
ICS:
13.060.50 3UHLVNDYDYRGHQDNHPLþQH Examination of water for
VQRYL chemical substances
SIST EN ISO 11905-1:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 11905-1:2000

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SIST EN ISO 11905-1:2000

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SIST EN ISO 11905-1:2000

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SIST EN ISO 11905-1:2000

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SIST EN ISO 11905-1:2000

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SIST EN ISO 11905-1:2000
INTERNATIONAL
IS0
STANDARD 11905-I ’
First edition
1997-05-O 1
Water quality -
Determination of
nitrogen -
Part 1:
Method using oxidative digestion with
peroxodisulfate
Qualitb de I’eau
- Dosage de I’azote -
Partie 7: Mkthode par min&alisation oxydante au peroxodisulfate
Reference number
IS0 11905-1:1997(E)

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SIST EN ISO 11905-1:2000
IS0 11905-1:1997(E)
Contents
1 Scope .
1
2 Normative references .
1
3 Range of detection .
1
4 Sensitivity
................................................................................... 1
5 Principle .
2
6 Reagents .
2
7 Apparatus .
5
8 Sampling and samples .
5
9 Procedure
...................................................................................
5
9.1 Test portion .
5
9.2 Blank test
.............................................................................
6
9.3 Cleaning digestion vessels
................................................ 6
9.4 Digestion .
6
9.5 Verification
of recovery of organic nitrogen. . 6
9.6 Starting operation .
6
9.7 Initial sensitivity setting .
8
9.8 Calibration .
8
99 . Determination .
8
10 Expression of results . 9
10.1 .
Method of calculation 9
10.2 Precision data .
9
11 Test report .
9
0 IS0 1997
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronic or mechanical,
including photocopying and microfilm, without permission in writing from the
publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
[e-mail]
X.400 c=ch; a=400net; p=iso; o=isocs; s=centraI
Printed in Switzerland
ii

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SIST EN ISO 11905-1:2000
IS0 119054:1997(E)
Annexes
10
A Precision data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
B Recovery data for some nitrogen-containing compounds . . . .
12
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C Determination of nitrate
13
D Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . .
III

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SIST EN ISO 11905-1:2000
IS0 11905-1:1997(E) 6 IS0
FOREWORD
IS0 (the International Organization for Standardization) is a worldwide federation of national
standards bodies (IS0 member bodies). The work of preparing International Standards is normally
carried out through IS0 technical committees. Each member body interested in a subject for which
a technical committee has been established has the right to be represented on that committee.
International organizations, governmental and non-governmental, in liaison with ISO, also take part
in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all
matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are circulated to the member
bodies for voting. Publication as an International Standard requires approval by at least 75 % of the
member bodies casting a vote.
International Standard IS0 11905-I was prepared by Technical Committee ISO~C 147, Water
quality, Subcommittee SC 2, Physical, chemical and biochemica/ methods.
IS0 11905 consists of the following parts, under the general title Water quality - Determination of
nitrogen:
- Part I: Method using oxidative digestion with peroxodisulfate
oxida tio n and combustion to nitrogen dioxide
Part 2: Determination of bound nitrogen after
using chemiluminescent detection
Annexes A to D of this part of IS0 11905 are for information only.
iv

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SIST EN ISO 11905-1:2000
IS0 119054:1997(E)
@ IS0
INTRODUCTION
This part of IS0 11905 describes the peroxodisulfate oxidation of nitrogen compounds in water to produce
nitrate. Specific details of the determination of a continuous flow method with initial reduction of nitrate to
nitrite by copperized cadmium are then reported. The procedures referred to in the normative method is the
reference method. Annex C gives examples of alternative techniques suitable for the determination of nitrate
in the digest solution. While staying within the scope of this part of IS0 11905, it is permissible to use such
alternatives only provided that their performance meets or is better than that given in table A.?, when
calculated using procedures described in IS0 5725-2, and when the comparison of precision data between this
part of IS0 11905 and any alternative technique is carried out using the procedures described in IS0 2854.
All references to nitrogen concentrations are expressed in milligrams of nitrogen per litre of solution (mg/l).

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SIST EN ISO 11905-1:2000
IS0 11905=1:1997(E)
INTERNATIONAL STANDARD 0 IS0
Water quality - Determination of nitrogen -
Part 1:
Method using oxidative digestion with peroxodisulfate
1 Scope
This part of IS0 11905 specifies a method for the determination of nitrogen present in water, in the form of free
ammonia, ammonium, nitrite, nitrate and organic nitrogen compounds capable of conversion to nitrate under
the oxidative conditions described.
Dissolved nitrogen gas is not determined by this method.
This method is applicable to the analysis of natural fresh water, sea water, drinking water, surface water and
treated sewage effluent. It is also applicable to the analysis of sewage and trade wastes in which the amount of
organic matter in the test portion can be kept below 40 mg/l, expressed as carbon (C), when measured by Total
Organic Carbon (TOC), or I20 mg/l, expressed as oxygen (O,), when measured by Chemical Oxygen Demand
(COD) according to the respective International Standards.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
part of IS0 11905. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this part of IS0 11905 are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0
maintain registers of current valid International Standards.
IS0 3696: 1987, Water for analytical laboratory use - Specification and test methods.
IS0 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results -
Part 2: Basic methods for the determination of repeatability and reproducibility of a standard
measurement method.
3 Range of detection
Using the maximum test portion specified in 9.1, nitrogen (N) can be determined in the range up to 5 mg/l.
Much higher concentrations can be determined using smaller test portions.
Using the maximum test portion, the lower limit of detection, expressed as N, is typically 0,02 mg/l. This
depends on the method used to measure the nitrate concentration resulting from the oxidation.
4 Sensitivity
Sensitivity will depend upon the method used to measure the nitrate concentration resulting from the
oxidation.

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SIST EN ISO 11905-1:2000
IS0 119054:1997(E) 0 IS0
The main potential interference effects arise from dissolved or suspended organic matter present in samples,
which compete for the oxidation capacity of the peroxodisulfate reagent. To guarantee a sufficient excess of
the oxidation reagent, if the COD of the original sample exceeds 120 mg/l, expressed as 0,, or the TOC exceeds
40 mg/l, expressed as C, the sample needs to be diluted.
Not all organic nitrogen compounds are quantitatively converted to nitrate by the oxidation. Poor recoveries
can occur with compounds containing double- and triple-bonded nitrogen atoms and also with those
substances containing a >C=NH group. Compounds with free amino groups give less than quantitative
recovery, but in no case less than 87%; good recoveries of nitrogen are reported for several heterocyclic
compounds, see annex B. Overall, the method gives good recovery performance for organic nitrogen
compounds and gives results not significantly different from those obtained by instrumental, high temperature
oxidation or reduction systems on a wide range of real samples containing significant amounts of organic
matter.
5 Principle
Ammonia, nitrite and many organic nitrogen-containing compounds in the test sample are oxidized to nitrate
using peroxodisulfate in a buffered alkaline system by boiling at elevated pressure in a closed container.
Subsequent reduction of nitrate to nitrite is carried out by passage of the digest through a mixing coil
containing copperized cadmium. The resulting nitrite is reacted with 4-aminobenzene sulfonamide and N-(l-
naphthyl)-1,2-diaminoethane dihydrochloride to produce a pink colour. Photometric measurement is carried
out at 540 nm.
6 Reagents
During the analysis, use water of purity grade 3 as specified in IS0 3696 and reagents of recognized analytical
grade.
6.1 Sulfuric acid, c(H,SO,) ==: 4 mol/l.
Carefully mix (110 +. O,5) ml of concentrated sulfuric acid (H,SO,, p = I,84 g/ml) into about 350 ml of water.
Allow to cool to room temperature and dilute with water to (500 t IO) ml. Store in a glass or plastics container.
This reagent is stable indefinitely.
WARNING: This reagent can cause severe burns. Wear gloves and eye protection when handling or preparing
the acid.
6.2 Sodium hydroxide solution, c(NaOH) ==: 0,375 mol/l.
Dissolve (IS,0 k 0,5) g of sodium hydroxide in about 900 ml of water. Allow to cool to room temperature and
make up to (1000 k 10) ml with water. Store in a polyethylene container. This reagent is stable for at least 6
months.
WARNING: This reagent is corrosive. Wear gloves and eye protection when handling or preparing the
solution.
6.3 Oxidizing solution.
Dissolve (5,0 k 0,l) g of analytical reagent grade potassium peroxodisulfate (K,S,OJ, containing not more than
0,001 % (m/m) nitrogen as impurity, and (3,00 -c- 0,05) g of boric acid (H,BO,) in (100 t 5) ml of sodium
hydroxide solution (6.2). Store the solution in a polyethylene container in the dark at room temperature. This
reagent is stable for up to one week.
2

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SIST EN ISO 11905-1:2000
IS0 119054:1997(E)
@ IS0
Wear gloves handling or preparing the
WARNING: This reagent is corrosive. and eye protection
solution.
6.4 Hydrochloric acid, c(HCI) ==: 5 mol/l.
Cautiously add (450 t 10) ml of concentrated hydrochloric acid (HCI, p = I,18 g/ml) to (500 k IO) ml of water
with constant stirring. Make up to (1000 _ + 10) ml with water. Store in a glass or polyethylene bottle. This
solution is stable for at least six months.
WARNING : This reagent can cause severe burns. Wear protection handling or prepari
g w
the acid.
6.5 Hydrochloric acid, c(HCI) ==: 0,l mol/l.
Add (IO,0 + 0,5) ml of concentrated hydrochloric acid (HCI, p = I,18 g/ml) to about 900 ml of water. Mix and
make up to (1000 + 10) ml with water. Store in a glass or polyethylene bottle. This reagent is stable
indefinitely.
WARNING:
This reagent can cause severe burns. Wear gloves and eye protection when handling or preparing
a the acid.
6.6 Glycine solution, 200 mg/l, expressed as N.
Dissolve (1,072 k 0,001) g of glycine, H,NCH,COOH, in about 800 ml of water and dilute to one litre with water
in a calibrated flask. Store in a glass container. If stored in a refrigerator at 0 “C to 5 ‘C this reagent is stable for
at least one month.
6.7 Glycine solution, 2 mg/l, expressed as N.
Pipette (IO,00 2 0,Ol) ml of glycine solution (6.5) into a one-litre calibrated flask and make up to volume with
water. Prepare fresh solution for each batch of analyses.
NOTE - The concentration of this standard glycine solution should be chosen to match the expected range of
concentrations of nitrogen to be determined; for example, if lower nitrogen results are expected then the concentration of
the standard glycine solution should be reduced. (See also 9.5).
6.8 Reagent blank.
Carry out at least one blank test using the procedure described but replacing the test portion with water.
6.9 Copper sulfate solution.
Dissolve (20 -c- 0,2) g of copper sulfate pentahydrate (CuSO, . 5 H,O) in (1000 * 10) ml of water. Store in a
glass or polyethylene bottle. This solution is stable for at least six months.
6.10 Copperized cadmium granules
WARNING: Cadmium is toxic by inhalation, by contact with skin or by ingestion.
Wash (10 k 0,l) g of cadmium granules (250 pm to 425 pm) in (50 2 0,5) ml of hydrochloric acid (6.4). Rinse the
granules three times in water by decantation. Add (100 -c 1) ml of copper sulfate solution (6.9) and swirl the
granules for 5 min or until the blue colour partially fades. Decant off the solution and repeat the procedure
with fresh copper sulfate solution (6.9) until a brown colloidal precipitate forms. Finally, wash the
copperized cadmium granules with water until all precipitated copper is removed. Carry out a minimum of 10
washes. Store the copperized granules under water until required. Avoid contact with air.
6.11 Buffer solution.
Dissolve (85,0 -c O,5) g of ammonium chloride (NH,CI) in about 800 ml of water. Add (I,0 2 0,l) g of wetting
agent (6.13). Make up to (1000 + 10) ml with water and store in a glass bottle. This solution is stable for at
least one month.
3

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SIST EN ISO 11905-1:2000
@ IS0
IS0 119054:1997(E)
6.12 Colour reagent.
Dissolve (40 + 0,5) g of 4-aminobenzene sulfonamide (NH,C,H,SO,NH,) in a mixture of (100 + 1) ml of
orthophosphoric acid (H,PO,, p = I,71 g/ml) and (500 t 50) ml of water in a beaker. Dissolve (2,00 A 0,2) g of N-
(I-naphthyl)-1,2-diaminoethane dihydrochloride (C,,H,NHCH,CH,NH, . 2HCI) in the resulting solution. Transfer
to a 1000 ml calibrated flask and dilute to the mark with water. Mix well. Store in an amber glass bottle. The
solution is stable for 1 month if stored at 2 “C to 5 “C.
WARNING: N-( I-naphthyl)-1,Zdiaminoethane dihydrochloride is toxic by inhalation, by contact with skin or
by ingestion.
6.13 Wetting agent.
NOTE - The presence of a wetting agent in a continuous-flow system is desirable in order to promote smooth hydraulic
flow.
Use a nonionic sutfactant of the polyoxyethylene alcohol type or the alkylphenoxypolyethoxy ethanol type.
6.14 Nitrate solution, containing 1000 mg/l, expressed as N.
Dissolve (7,215 k 0,001) g of potassium nitrate (KNO,) (previously dried at 105 “C for at least 2 h) in about 750
ml of water. Quantitatively transfer to a one-litre calibrated flask and make up to volume wit
...