Bsi bs en 13466 2 2001 (2011)

Unknown BRITISH STANDARD BS EN 13466 2 2001 Fertilizers — Determination of water content (Karl Fischer methods) — Part 2 2 propanol as extracting medium The European Standard EN 13466 2 2001 has the s[.]

BRITISH STANDARD BS EN

13466-2:2001

Fertilizers —

Determination of water

content (Karl Fischer

methods) —

Part 2: 2-propanol as extracting medium

The European Standard EN 13466-2:2001 has the status of a

British Standard

ICS 65.080

Confirmed June 2011

This British Standard, having

been prepared under the

direction of the Materials and

Chemicals Sector Policy and

Strategy Committee, was

published under the authority

of the Standards Policy and

Strategy Committee on

10 April 2002

© BSI 10 April 2002

ISBN 0 580 39473 5

National foreword

This British Standard is the official English language version of

EN 13466-2:2001

The UK participation in its preparation was entrusted to Technical Committee CII/37, Fertilizers and related chemicals, which has the responsibility to:

A list of organizations represented on this committee can be obtained on request to its secretary

Cross-references

The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic

Catalogue

A British Standard does not purport to include all the necessary provisions of

a contract Users of British Standards are responsible for their correct application

Compliance with a British Standard does not of itself confer immunity from legal obligations.

— aid enquirers to understand the text;

— present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed;

— monitor related international and European developments and promulgate them in the UK

Summary of pages

This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 10, an inside back cover and a back cover

The BSI copyright date displayed in this document indicates when the document was last issued

Amendments issued since publication

EUROPEAN STANDARD

NORME EUROPÉENNE

EUROPÄISCHE NORM

EN 13466-2

October 2001

ICS 65.080

English version

Fertilizers - Determination of water content (Karl Fischer methods) - Part 2: 2-propanol as extracting medium

Engrais - Détermination de la teneur en eau (Méthodes Karl

Fischer) - Partie 2: 2-propanol comme milieu d'extraction Fischer-Verfahren) - Teil 2: 2-Propanol als ExtraktionsmittelDüngemittel - Bestimmung des Wassergehaltes

(Karl-This European Standard was approved by CEN on 18 August 2001.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION

C O M I T É E U R O P É E N D E N O R M A L I S A T I O N

E U R O P Ä IS C H E S K O M IT E E FÜ R N O R M U N G

Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2001 CEN All rights of exploitation in any form and by any means reserved

Contents

page

Foreword 3

Introduction 4

1 Scope 5

2 Normative references 5

3 Principle 5

4 Reagents 5

5 Apparatus 5

6 Installation and test of the Karl Fischer titrator 6

7 Sampling 6

8 Procedure 6

9 Calculation and expression of results 8

10 Precision 8

11 Test report 8

Bibliography 10

EN 13466-2:2001 (E)

3

Foreword

This European Standard has been prepared by Technical Committee CEN/TC 260 "Fertilizers and liming materials", the secretariat of which is held by DIN

This European Standard shall be given the status of a national standard, either by publication of an identical text or

by endorsement, at the latest by April 2002, and conflicting national standards shall be withdrawn at the latest by April 2002

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom

Introduction

The water content of fertilizers has a significant effect on their quality and, especially, their storage and handling properties

Water can be present in a number of forms such as free water, bound water and water of crystallization It is often important to be able to distinguish between these forms of water The gravimetric methods for determination of water standardized in EN 12048 and EN 12049 have only limited applicability

The Karl Fischer method is applicable to a wide range of fertilizers However, there are several variations to the basic technique, different formulations of the Karl Fischer reagents are commercially available and a number of different solvents can be used In this standard, methanol and 2-propanol are used as extracting media to distinguish between the different forms of water present in fertilizers

EN 13466 "Fertilizers – Determination of water content (Karl Fischer methods)" consists of two parts:

Part 1 : Methanol as extracting medium

Part 2 : 2-propanol as extracting medium

As examples of the difference between methanol and 2-propanol as extracting media methanol gives a result which

is a combination of free water and extracted water of crystallization from the following components of fertilizers: calcium nitrate tetrahydrate (Ca(NO3)2·4H2O); calcium hydrogen phosphate dihydrate (CaHPO4·2H2O) ; calcium sulfate dihydrate (gypsum, CaSO4·2H2O) calcium sulfate hemihydrate (CaSO4·0,5H2O) ; magnesium sulfate heptahydrate (MgSO4·7H2O); potassium chloride magnesium sulfate water (1/1/2,75, Kainite, KCl· MgSO4·2,75H2O) ; potassium magnesium sulfate hexahydrate (Schoenite, K2SO4·MgSO4·6H2O) ; potassium magnesium sulfate tetrahydrate (Leonite, K2SO4·MgSO4·4H2O) ; potassium sulfate calcium sulfate monohydrate (Syngenite, K2SO4·CaSO4·H2O); potassium chloride magnesium chloride hexahydrate (Carnallite, KCl· MgCl2·6H2O); magnesium nitrate hexahydrate (Mg(NO3)2·6H2O)

Extraction with 2-propanol gives a result which is a combination of free water and extracted water of crystallization from the following components of fertilizers: calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) ; magnesium sulfate heptahydrate (MgSO4·7H2O); potassium chloride magnesium chloride hexahydrate (Carnallite, KCl·MgCl2·6H2O); magnesium nitrate hexahydrate (Mg(NO3)2·6H2O)

EN 13466-2:2001 (E)

5

1 Scope

This European standard specifies a Karl Fischer titrimetric method for the determination of the water content of fertilizers based on the use of 2-propanol as extracting medium

The method is applicable to all solid mineral fertilizers The result (KFP water) includes "free" water and extracted water of crystallization from the following components of fertilizers: calcium nitrate tetrahydrate (Ca(NO3)2·4H2O); magnesium sulfate heptahydrate (MgSO4·7H2O); potassium chloride magnesium chloride hexahydrate (Carnallite, KCl·MgCl2·6H2O); magnesium nitrate hexahydrate (Mg(NO3)2·6H2O)

2 Normative references

This European Standard incorporates by dated or undated reference, provisions from other publications These normative references are cited at the appropriate places in the text, and the publications are listed hereafter For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision For undated references the latest edition of the publication referred to applies (including amendments)

EN 1482, Sampling of solid fertilizers and liming materials

3 Principle

Extraction of water from the fertilizer into 2-propanol, separation of the clear solution and titration of the extracted water with a Karl Fischer reagent, previously standardized by titration with a known mass of water

4 Reagents

4.1 General

All reagents shall be of recognized analytical grade

4.2 2-propanol, containing less than a mass concentration of 250 mg/l water.

4.3 Karl Fischer reagent, equivalence from 1 mg to 5 mg water/ml reagent (see Table 1).

4.4 Sodium tartrate dihydrate Na2C4H4O6 · 2H2O (15,66% mass fraction of water)

Sodium tartrate dihydrate Na2C4H4O6 ·2H2O can be stored over 60% H2SO4 in a desiccator Check the water content by drying at about 150°C

5 Apparatus

Ordinary laboratory apparatus and glassware and in particular the following:

5.1 Balance, capable of weighing to the nearest 0,0001 g.

5.2 Centrifuge capable of operating at a rate of 3 500 min-1

5.3 Centrifuge tubes, diameter 4,5 cm, height 10 cm fitted with rubber stoppers.

5.4 Dispersing apparatus : turbine type, minimum rotational frequency 9 500 min-1, suitable for introduction into centrifuge tubes (5.3), for instance Ultra Turrax 1

5.5 Karl Fischer titrator

NOTE There are several titrators on the market for the Karl Fischer method

6 Installation and test of the Karl Fischer titrator

Follow the instruction manual for the particular titrator used

7 Sampling

Carry out sampling in accordance with EN 1482

8 Procedure

8.1 Calibration of the Karl Fischer reagent

Titrate a known amount of water or sodium tartrate dihydrate (4.4) accurately weighed to the nearest 0,0001 g following the instruction manual for the titrator

NOTE Calibration frequency should be adapted to the frequency of analysis

8.2 Drift

Control the diffusion of water from the air into the titration vessel during the determination following the instruction manual for the titrator Take account of any recorded drift (md) when expressing results

8.3 Test portion

Weigh to the nearest 0,0001 g a test portion of the test sample in accordance with clause 7 and Table 1 directly into the previously dried and tared centrifuge tube (5.3)

Table 1 — Mass of test portion

Mass of test portion Expected water content

[mass fraction in %]

titre of KF-Reagent

5 mg/ml

titre of KF-Reagent

2 mg/ml

1 Ultra Turrax S25 equipped with dispersing turbine S25KR - 18G is an example of equipment commercially available This information is given for the convenience of users of this European Standard and does not constitute

an endorsement by CEN of these products

EN 13466-2:2001 (E)

7

8.4 Extraction

Add 25 ml of 2-propanol (4.2) with a calibrated pipette to the test portion in the centrifuge tube Insert the dispersing apparatus (5.4) ensuring that the distance from any part of the dispersing tool to the inner surface of the centrifuge tube is greater than the grain size of the fertilizer

Place the dispersing tool near to the surface of the fertilizer layer Disperse for 60 s at room temperature at

9 500 min-1 at least

Make sure that the temperature during the dispersion-extraction does not exceed 40 °C or, in the case of fertilizer containing magnesium sulfate, 25 °C

Repeat the dispersion for a further 60 s if the fertilizer has not been completely dispersed in the first operation Repeat the extraction if the dispersion is still not complete

NOTE The dispersion can be controlled acoustically; the turbine pitch changes once the dispersion is complete

8.5 Separation

Remove the dispersion apparatus from the centrifuge tube and stopper the latter with the rubber stopper Centrifuge the tube for 5 min Repeat for 5 min if the supernatant liquid is not clear

8.6 Titration

Introduce 5,0 ml of the clear solution (8.3) into the reaction vessel of the titrator (5.5) Start stirring Titrate with the Karl Fischer reagent (4.3) until the equivalence point is reached, following the instruction manual for the titrator Record the mass ms, in milligrams of water, indicated by the titrator

8.7 Blank test

Carry out a blank test following the procedure specified in 8.2 but omitting the test portion Record the mass mb

8.8 Replication

Repeat the procedure described in 8.1 to 8.6 using a second test portion from the same test sample After use the dispersing tool should be cleaned and dried

8.9 Alternative procedure for a series of samples

8.9.1 If a serial analysis is contemplated for several samples an alternative procedure may be used provided enough 2-propanol can be held in the titrator reaction vessel to accomodate all the samples and the ensuing quantity of Karl Fischer reagent The procedure is as given in 8.9.2 to 8.9.8

8.9.2 Check for drift as described in 8.2

8.9.3 Introduce 5 ml of 2-propanol (4.2)

8.9.4 Add the Karl Fischer reagent until the equivalence point is reached Reset the titrator readings to zero

8.9.5 Introduce exactly 5 ml of extractant resulting from the separation (see 8.5)

8.9.6 Titrate to the equivalence point whilst stirring Record the reading Reset the readings to zero Stop stirring

8.9.7 Introduce a further 5 ml of extractant resulting from the separation (see 8.5) Repeat the procedure described in 8.9.6

8.9.8 Carry out a blank test as described in 8.7

9 Calculation and expression of results

The water content of the sample, wKFP, expressed as mass fraction in percent, in accordance with the Karl Fischer method with 2-propanol as extracting medium is given by the following equation:

t

d b s

KFP

100 ) (

5

m

m m m

where

ms is the mass of water in the sample recorded in 8.6, in milligrams;

mb is the mass of water obtained by blank test (8.7), in milligrams;

md is the mass of water measured as per 8.2, in milligrams;

mt is the mass of the test portion, in milligrams

Report the mean of two determinations

10 Precision

10.1 Interlaboratory test

An interlaboratory test was carried out in April 1997 with 15 participating laboratories and five different fertilizer formulae These formulae were: ammonium nitrate (AN) from two different sources, calcium ammonium nitrate (CAN), NPK of the formula 12+12+17+2 and Thomas Kali (PK) For additional information see [1]

10.2 Repeatability

The absolute difference between two single test results obtained with the same method on identical test material in the same laboratory by the same operator using the same equipment within the shortest feasible time interval will exceed the repeatability limit r in not more than 5 % of the cases

r = 0,033 + 0,049 wKFP

The equation being a + b
wKFP.

10.3 Reproducibility

The absolute difference between two single test results obtained with the same method on identical test material in different laboratories with different operators using different equipment will exceed the reproducibility limit R in not more than 5 % of the cases

R = 0,177 + 0,293 wKFP

The equation being a + b
wKFP.

11 Test report

The test report shall include the following information:

a) a reference to this European Standard;

b) a complete identification of the sample;

c) a reference to the test method used;