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1、A Reference number ISO 6495:1999(E) INTERNATIONAL STANDARD ISO 6495 Second edition 1999-04-01 Animal feeding stuffs Determination of water-soluble chlorides content Aliments des animaux Dtermination de la teneur en chlorures solubles dans leau Copyright International Organization for Standardization
2、 Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 22:14:24 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 6495:1999(E) ISO 1999 All rights reserved. Unless otherwise specified, no part of this publication
3、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 CH-1211 Genve 20 Switzerland Internetisoiso.ch Printed in Switze
4、rland ii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for
5、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. ISO collaborates closely with the International Electrotechnical Commission (IEC) on al
6、l matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International S
7、tandard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 6495 was prepared by Technical Committee ISO/TC 34, Agricultural food products, Subcommittee SC 10, Animal feeding stuffs. This second edition of ISO 6495 cancels and replaces the first edition
8、 (ISO 6495:1980), which has been technically revised. Annex A of this International Standard is for information only. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 22:14:24 MDT
9、No reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISOISO 6495:1999(E) 1 Animal feeding stuffs Determination of water-soluble chlorides content 1 Scope This International Standard specifies a method for the determination of the water-soluble chlorides conte
10、nt, expressed as sodium chloride, of animal feeding stuffs. The method is applicable to animal feeding stuffs. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references
11、, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated referenc
12、es, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 3696, Water for analytical laboratory use Specification and test methods. ISO 6498, Animal feeding stuffs Preparation of test samples. 3 Pri
13、nciple The chlorides present in a test portion are dissolved in water. The solution is clarified if the product contains organic matter. It is then slightly acidified with nitric acid and the chlorides are precipitated as silver chloride by means of standard volumetric silver nitrate solution. The e
14、xcess silver nitrate is titrated with a standard volumetric solution of ammonium thiocyanate or potassium thiocyanate. 4 Reagents Use only reagents of recognized analytical grade. 4.1 Water, complying with at least grade 3 in accordance with ISO 3696. 4.2 Acetone. 4.3 n-Hexane. 4.4 Nitric acid, r20(
15、HNO3) = 1,38 g/ml. 4.5 Activated carbon, free from chlorides and not capable of adsorbing chlorides. 4.6 Ammonium iron(III) sulfate, saturated solution. Prepare from NH4Fe(SO4)212H2O. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Techni
16、cal Standards 1/9972545001 Not for Resale, 04/24/2007 22:14:24 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 6495:1999(E) ISO 2 4.7 Carrez I solution. Dissolve in water, 10,6 g of potassium hexacyanoferrate(II) trihydrate K4Fe(CN)63H2O. Dilute to 100 ml with water. 4.
17、8 Carrez II solution. Dissolve in water, 21,9 g of zinc acetate dihydrate Zn(CH3COO)22H2O and add 3 ml of glacial acetic acid. Dilute to 100 ml with water. 4.9 Ammonium thiocyanate or potassium thiocyanate, standard volumetric solution, c(NH4SCN) = 0,1 mol/l or c(KSCN) = 0,1 mol/l. 4.10 Silver nitra
18、te, standard volumetric solution, c(AgNO3) = 0,1 mol/l. 5 Apparatus Usual laboratory apparatus and, in particular, the following. 5.1 Rotary shaker, operating at a rotation frequency of approximately 35 min1 to 40 min1. 5.2 One-mark volumetric flasks, of capacities 200 ml and 500 ml. 5.3 Pipettes, o
19、f appropriate capacity. 5.4 Burettes. 5.5 Analytical balance, capable of weighing to the nearest 0,001 g. 6 Sampling Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 6497 1. It is important that the laboratory receive a sample
20、 which is truly representative and has not been damaged or changed during transport or storage. 7 Preparation of test sample Prepare the test sample in accordance with ISO 6498. If solid, grind the laboratory sample (usually 500 g) so that it passes completely through a sieve with 1 mm apertures. Mi
21、x thoroughly. 8 Procedure NOTE If it is required to check whether the repeatability limit is met (see 10.2), carry out two single determinations in accordance with 8.1 to 8.5. 8.1 Procedure selection If the test sample is free from organic matter, proceed in accordance with 8.2. Copyright Internatio
22、nal Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 22:14:24 MDTNo reproduction or networking permitted without license from IHS -,-,- ISOISO 6495:1999(E) 3 If the test sample contains organic matter, p
23、roceed in accordance with 8.3, unless the test sample concerns cooked feeding stuffs, flax cakes and flour, products rich in flax flour, and other products rich in mucilage or in colloidal substances (e.g. dextrinated starch). In this case proceed in accordance with 8.4. 8.2 Preparation of test solu
24、tion of samples free from organic matter Weigh, to the nearest 0,001 g, a test portion (mass m) of the prepared test sample of not more than 10 g presumed to contain not more than 3 g of chlorides. Transfer to a 500 ml volumetric flask (5.2) and add 400 ml of water at a temperature of approximately
25、20 C. Mix for 30 min in the rotary shaker (5.1), dilute to the mark with water (resulting volume Vi), then mix and filter. Proceed in accordance with 8.5. 8.3 Preparation of test solution of samples containing organic matter, excluding the products listed in 8.4 Weigh approximately 5 g (mass m) of t
26、he prepared test sample to the nearest 0,001 g and transfer to a 500 ml volumetric flask (5.2). Add 1 g of activated carbon (4.5), 400 ml of water at a temperature of approximately 20 C, and 5 ml of Carrez I solution (4.7). Stir, then add 5 ml of Carrez II solution (4.8). Mix for 30 min on the rotar
27、y shaker (5.1). Dilute to the mark with water (resulting volume Vi), mix and filter. Proceed in accordance with 8.5. 8.4 Cooked feeding stuffs, flax cakes and flour, products rich in flax flour, and other products rich in mucilage or in colloidal substances Weigh approximately 5 g (mass m) of the pr
28、epared test sample to the nearest 0,001 g and transfer to a 500 ml volumetric flask (5.2). Add 1 g of activated carbon (4.5), 400 ml of water at a temperature of approximately 20 C, and 5 ml of Carrez I solution (4.7). Stir, then add 5 ml of Carrez II solution (4.8). Mix for 30 min on the rotary sha
29、ker (5.1). Dilute to the mark with water (resulting volume Vi) and mix. Decant (if necessary, centrifuge). By means of a pipette (5.3), transfer 100 ml of the supernatant liquid to a 200 ml volumetric flask (5.2). Mix with acetone (4.2), dilute to the mark with the same solvent, mix and filter. 8.5
30、Titration By means of a pipette (5.3), transfer to a conical flask an aliquot portion of between 25 ml and 100 ml (volume Va) of the filtrate. The aliquot portion shall not contain more than 150 mg of chloride. Dilute, if necessary, to a volume of not less than 50 ml with water. Add 5 ml of nitric a
31、cid (4.4), 2 ml of ammonium iron(III) sulfate solution (4.6) and 2 drops of ammonium thiocyanate solution or potassium thiocyanate solution (4.9) from a burette (5.4) filled to the zero mark. NOTE The remainder of the solution is to be used for titration of the excess silver nitrate. Add from a bure
32、tte (5.4), silver nitrate solution (4.10) until the reddish-brown tint disappears, then add an excess of 5 ml (resulting volume Vs1). Shake vigorously to coagulate the precipitate. If necessary, 5 ml of n-hexane (4.3) may be added to assist coagulation. Titrate the excess silver nitrate with ammoniu
33、m thiocyanate solution or potassium thiocyanate solution (4.9) until a reddish brown tint, persisting for at least 30 s, develops (resulting volume Vt1). Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not
34、 for Resale, 04/24/2007 22:14:24 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 6495:1999(E) ISO 4 8.6 Blank test Carry out a blank test in parallel with the determination, using the same procedure and the same reagents, but omitting the test portion. 9 Expression of r
35、esults Calculate the water-soluble chlorides content, expressed as sodium chloride, by the equation: wc sssttti a w = M V V c V V m V V f ()() 100 % 1010 c where wwcis the water-soluble chlorides content, expressed as sodium chloride, as percentage by mass, of the test sample; Mis the molar mass, in
36、 grams per mole, of sodium chloride (M = 58,44 g/mol); Vs1is the volume, in millilitres, of the silver nitrate solution added for the titration of the test solution (8.5); Vs0is the volume, in millilitres, of the silver nitrate solution added for the titration of the blank solution (8.6); csis the c
37、oncentration, in moles per litre, of the silver nitrate solution (4.10); Vt1is the volume, in millilitres, of the ammonium thiocyanate solution or potassium thiocyanate solution used in the titration of the test solution (8.5); Vt0is the volume, in millilitres, of the ammonium thiocyanate solution o
38、r potassium thiocyanate solution used in the titration of the blank solution (8.6); ctis the concentration, in moles per litre, of the ammonium thiocyanate or potassium thiocyanate solution (4.9); mis the mass, in milligrams, of the test portion; Viis the volume, in millilitres, of the test solution
39、 prepared in 8.2, 8.3 and 8.4 (Vi = 500 ml); Vais the volume, in millilitres, of the aliquot portion of filtrate taken (see 8.5); fis a dilution factor: f = 2for cooked feeding stuffs, flax cakes and flour, products rich in flax flour and other products in mucilage or in colloidal substances (see 8.
40、4); f = 1for other animal feeding stuffs (see 8.2 and 8.3). Report the result1) to the nearest: 0,05 % for water-soluble chlorides contents less than 1,5 %; 0,1 % for water-soluble chlorides contents greater than or equal to 1,5 %. 1) Expressed as percentage by mass % (m/m). Copyright International
41、Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 22:14:24 MDTNo reproduction or networking permitted without license from IHS -,-,- ISOISO 6495:1999(E) 5 10 Precision 10.1 Interlaboratory test Details of
42、 an interlaboratory test on the precision of the method are summarized in annex A. The values derived from this interlaboratory test may not be applicable to concentrations ranges and matrices other than those given. 10.2 Repeatability The absolute difference between two independent single test resu
43、lts, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, will in not more than 5 % of cases exceed the repeatability limit (r) derived from the equation: ()rw= 0134 0 521 , , wc where ris the
44、repeatability limit, expressed as percentage by mass; wc w is the mean of the two single test results, expressed as percentage by mass. 10.3 Reproducibility The absolute difference between two single test results, obtained using the same method on identical test material in different laboratories by
45、 different operators using different equipment, will in not more than 5 % of cases exceed the reproducibility limit (R) derived from the equation: R = 0,552 % + 0,135 wwc where Ris the reproducibility limit, expressed as percentage by mass; wc w is the mean of the two single test results, expressed
46、as percentage by mass. 11 Test report The test report shall specify: all information necessary for the complete identification of the sample; the sampling method used, if known; the test method used, with reference to this International Standard; all operating details not specified in this Internati
47、onal Standard, or regarded as optional, together with details of any incidents which may have influenced the test results; the test result(s) obtained; or if the repeatability has been checked, the final quoted result obtained. Copyright International Organization for Standardization Provided by IHS
48、 under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 22:14:24 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 6495:1999(E) ISO 6 Annex A (informative) Results of interlaboratory test An interlaboratory test was organized by ISO/TC 34/SC 10, Animal feeding stuffs, in 1987 and carried out in accordance with ISO 5725:19862. The final statistical analysis was carried out in accordance with ISO 5725-2:19944. In the test 24 laboratories participated. Samples