1、BRITISH STANDARD BS 5551-4.5: 1993 ISO 10084: 1992 Fertilizers Part 4: Chemical analysis Section 4.5 Method for determination of mineral-acid-soluble sulfate content of solid fertilizers UDC 631.8:543.21:546.226BS5551-4.5:1993 This British Standard, having been prepared under the directionof the Che
2、micals Standards Policy Committee, waspublished under the authorityof the Standards Boardand comes into effect on 15 February 1993 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference CIC/37 Draft for comment 91/56350 DC ISBN 0 580 21960 7 Committees resp
3、onsible for this British Standard The preparation of this British Standard was entrusted by the Chemicals Standards Policy Committee (CIC/-) to Technical Committee CIC/37, upon which the following bodies were represented: Association of Public Analysts British Aggregate Construction Materials Indust
4、ries British Coal Corporation Chemical Industries Association Consumers Association Department of Trade and Industry (Laboratory of the Government Chemist) Fertiliser Manufacturers Association Ltd. Horticultural Trades Association Institute of Trading Standards Administration Ministry of Agriculture
5、, Fisheries and Food Ministry of Defence Amendments issued since publication Amd. No. Date CommentsBS5551-4.5:1993 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative reference 1 3 Principles 1 4 Reagents 1 5 Apparatus 1 6 Preparation of t
6、he test sample 1 7 Procedure 1 8 Calculation and expression of results 2 9 Precision 2 10 Test report 2 Table 1 Mass of test portion in relation to the expected acid-soluble sulfate content 1 List of references Inside back coverBS5551-4.5:1993 ii BSI 10-1999 National foreword This Section of BS 5551
7、 has been prepared under the direction of the Chemicals Standards Policy Committee. For some years the United Kingdom has participated in the standardization of methods of sampling fertilizers through Subcommittee4, Chemical analysis, of Technical Committee134, Fertilizers and soil conditioners, of
8、the International Organization for Standardization (ISO). As international agreement is reached on the methods, it is proposed to publish them as Sections of BS5551. BS 5551 is published in four Parts, each Part being subdivided into Sections and, where appropriate, Subsections. The four Parts are:
9、Part 1: Terminology and labelling; Part 2: Sampling; Part 3: Physical properties; Part 4: Chemical analysis. This Section of Part4 is identical with ISO10084:1992 Solid fertilizers Determination of mineral-acid-soluble sulfate content Gravimetric method. A British Standard does not purport to includ
10、e 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. Cross-references International Standard Corresponding British Standard BS 5551 Fertili
11、zers ISO 8358:1991 Section 2.8:1991 Methods for preparation of samples of solid fertilizer for chemical and physical analysis (Identical) BS 5497 Precision of test methods ISO 5725:1986 Part 1:1987 Guide for the determination of repeatability and reproducibility for a standard test method by inter-l
12、aboratory tests (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the
13、amendment table on the inside front cover.BS5551-4.5:1993 BSI 10-1999 1 1 Scope This International Standard specifies a method for the gravimetric determination of the mineral-acid-soluble sulfate content of solid fertilizers. The method is applicable to fertilizers with sulfate contents, expressed
14、as SO 3 , from3%(m/m) to50%(m/m). 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and part
15、ies to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 8358:1991, Solid fertilizers Preparation
16、 of samples for chemical and physical analysis. 3 Principles Dissolution of soluble sulfates in hydrochloric acid solution. Precipitation of sulfate ions in a hydrochloric acid medium with barium chloride. Filtration, washing, drying, ignition and weighing of the precipitate. 4 Reagents All reagents
17、 shall be of recognized analytical grade. The water used shall be distilled water or water of equivalent purity. 4.1 Hydrochloric acid solution, 20 =1,19g/ml. 4.2 Barium chloride dihydrate solution, c(BaCl 2 2H 2 O)=122g/l. 4.3 Silver nitrate solution, c(AgNO 3 ) =5 g/l. 5 Apparatus Ordinary laborat
18、ory apparatus and the following. 5.1 Electric hot-plate 5.2 Filter crucibles with porcelain disc, porosity grade P10, pore size index44m to104m. 5.3 Oven, capable of being maintained at a temperature of120 C 5 C. 5.4 Oven, capable of being maintained at a temperature of800 C 50 C. 5.5 Desiccator, fi
19、lled with a suitable desiccant. 6 Preparation of the test sample Prepare the laboratory sample according to ISO8358 and transfer at least 50g to the laboratory for analysis. 7 Procedure 7.1 Test portion Weigh, to the nearest0,1mg, the mass of the test sample (clause6) which, according toTable 1, cor
20、responds with the expected acid-soluble sulfate content. NOTE 1The amount of SO 3present in the test portion should be200mg to600mg. Table 1 Mass of test portion in relation to the expected acid-soluble sulfate content 7.2 Dissolution of the test portion Transfer the test portion (7.1) into a400ml b
21、eaker. Add170ml to180ml of water and15ml of hydrochloric acid(4.1). Bring to the boil and continue boiling for10min. Allow to cool. Transfer the mixture quantitatively to a one-mark250ml volumetric flask, with the aid of a funnel, and then rinse the beaker and the funnel into the same flask. Make up
22、 to the mark with water, mix and filter through a dry, folded filter paper, collecting the filtrate in a dry bottle. 7.3 Determination Transfer100ml of the filtrate(7.2) to a800ml beaker. Make up with water to300ml and add20ml of hydrochloric acid(4.1). Bring to the boil. While mixing thoroughly, ad
23、d drop by drop20ml of the barium chloride solution (4.2). Continue boiling for a few minutes. Place the beaker on the hot-plate(5.1) set at60 C and cover it with a watch-glass. Allow to stand at60 C for3h. Dry a filter crucible(5.2) in the oven(5.4) set at800 C. Allow it to cool in the desiccator(5.
24、5) then weigh to the nearest0,1mg. Expected acid-soluble sulfate content, as SO 3 Approximate mass of test portion % (m/m) g from to 3 5 10 5 10 5 10 30 2 30 50 1BS5551-4.5:1993 2 BSI 10-1999 Decant the clear supernatant liquid from the beaker through the crucible. Wash the precipitate in the beaker
25、 several times by decanting with hot water. Transfer the precipitate to the dried crucible by means of a hot water jet. Wash the precipitate with hot water in order to remove chloride ions. Continue washing until the absence of chloride ions has been established by means of the silver nitrate soluti
26、on(4.3). Dry the crucible with the precipitate for1h in the oven(5.3) set at120 C. Place the crucible in the oven(5.4) set at800 C and heat the dried precipitate for0,5h. Allow the crucible to cool in the desiccator and weigh to the nearest0,1mg. 8 Calculation and expression of results Calculate the
27、 mineral-acid-soluble sulfate content from the following equation: where Round the result obtained to the nearest0,01% (m/m). 9 Precision The precision of this method has been established by an international inter-laboratory test carried out in accordance with ISO5725:1986, Precision of test methods
28、 Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. In this test, six samples of different origin and acid-soluble sulfate contents were investigated by sixteen laboratories in seven countries. For the values obtained for repeatability limit and
29、reproducibility limit, a probability level of95% holds. 9.1 Repeatability The absolute difference between two single tests results, obtained under repeatability conditions, shall not exceed the value of r given by the formula r = 0,042% + 0,0091 whereis the arithmetic mean of the results expressed a
30、s SO 3 , as a percentage by mass. Reject both results if the difference exceeds the calculated value of r and carry out two new single determinations. If the repeatability requirement is met, calculate the arithmetic mean of the two results to the nearest0,01% (m/m). NOTE 2The following definitions
31、are taken from ISO5725. single test result: The result obtained by carrying out a specified test method one time according to the prescribed procedure. repeatability conditions: Conditions where mutually independent test results are obtained with the same method on identical test material in the sam
32、e laboratory by the same operator using the same equipment within short intervals of time. 9.2 Reproducibility The absolute difference between two single test results, obtained under reproducibility conditions, shall not exceed the value R given by the formula R = 0,098% +0,0284 whereis the arithmet
33、ic mean of the two results expressed as SO 3 , as a percentage by mass. NOTE 3The following definition is taken from ISO5725. reproducibility conditions: Conditions where test results are obtained with the same method on identical test material in different laboratories with different operators usin
34、g different equipment. 10 Test report The test report shall include the following information: a) all information necessary for the complete identification of the sample; b) a reference to this International Standard; c) the results and the method of expression used; d) any unusual features noted du
35、ring the determination; e) any operation not specified in this International Standard or regarded as optional. w S is the mineral-acid-soluble sulfate content expressed as SO 3 , as a percentage by mass; m 1 is the mass of the dried and heated precipitate, in grams; m 0 is the mass of the test porti
36、on, in grams. w s 85,75 m 1 m 0 - = w s w s w s w sBS5551-4.5:1993 BSI 10-1999 List of references See national foreword.BS 5551-4.5: 1993 ISO 10084: 1992 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStan
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