BS 4267-1-1988 Ammonium nitrate - Method for determination of ammoniacal nitrogen content《硝酸铵 第1部分 氨型氮含量测定方法》.pdf

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1、BRITISH STANDARD BS 4267-1: 1988 Ammonium nitrate Part 1: Method for determination of ammoniacal nitrogen content NOTEIt is recommended that this Part of BS4267 be read in conjunction with the information in the “General introduction”, published separately as BS4267-0. WARNING. Ammonium nitrate is a

2、 strong oxidizing agent. If necessary, break the test sample up by crushing rather than grinding. UDC 661.525:546.39:546.39:549.751.13:543:620.1BS4267-1:1988 This British Standard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authority ofthe B

3、oard of BSI and comes into effect on 29July1988 BSI 10-1999 The Committees responsible for this British Standard are shown inPart0 The following BSI references relate to the work on this standard: Committee reference CIC/21 Draft for comment 84/54870 DC ISBN 0 580 16750 X Foreword This Part of BS 42

4、67 has been prepared under the direction of the Chemicals Standards Committee. It supersedes clause2 of BS4267:1968, which is withdrawn. This Part of BS4267 is related to BS5551-4.1.2:1982 which is identical with ISO5314:1981. This British Standard describes a method of test only, and should not be

5、used or quoted as a specification defining limits of purity. Reference to this Part should indicate that the method of test used is in accordance with BS4267-1:1988. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible

6、for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 4, an inside back cover and a back cover. This standard has been upda

7、ted (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS4267-1:1988 BSI 10-1999 i Contents Page Foreword ii 1 Scope 1 2 Principle 1 3 Reagents 1 4

8、Apparatus 1 5 Procedure 1 6 Expression of results 2 7 Test report 2 Figure 1 Typical distillation apparatus (using a round bottomed flask) 3 Publications referred to Inside back coverii blankBS4267-1:1988 BSI 10-1999 1 1 Scope This Part of BS 4267 describes a titrimetric method, after distillation,

9、for the determination of the ammoniacal nitrogen content of ammonium nitrate for industrial use. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Principle The ammonia in a sample is distilled from an alkaline solution, absorbed in an excess of s

10、tandard volumetric sulphuric acid solution and back-titrated with standard volumetric sodium hydroxide solution, with methyl red or screened methyl red as indicator. 3 Reagents 3.1 General. During the analysis, use only reagents of recognized analytical grade and water complying with grade3 of BS397

11、8 3.2 Ammonium nitrate, anhydrous. Heat approximately5g of ammonium nitrate on a clean platinum dish, in an oven controlled at100 2 C, cool in a desiccator and weigh. Repeat this procedure until successive weighings do not differ by more than0.01g. 3.3 Sodium hydroxide solution, approximately400g/L.

12、 3.4 Sodium hydroxide, standard volumetric solution, c(NaOH) =0.10mol/L. 3.5 Sulphuric acid, standard volumetric solution, c(H 2 SO 4 ) =0.05mol/L. 3.6 Indicator solution, either a) or b). a) Screened methyl red indicator solution. Mix50mL of a2g/L solution of methyl red in95% (V/V) ethanol with50mL

13、 of a1g/L solution of methylene blue in95% (V/V) ethanol. b) Methyl red indicator solution. Dissolve0.1g of methyl red in50mL of95% (V/V) ethanol. NOTEFor the purposes of3.6, the ethanol may be replaced by industrial methylated spirits95% (V/V) complying with BS3591. It should be noted that the use

14、of industrial methylated spirits is governed by The Methylated Spirits Regulations,1983 (S.I.1983No.252). It is not permissible to use duty-free ethanol, received under the provisions of the Alcoholic Liquors Duties Act1972, Section10, for purposes for which industrial methylated spirits is an accep

15、table alternative. 3.7 pH indicator paper, wide range. 4 Apparatus 4.1 Ordinary laboratory apparatus 4.2 Distillation apparatus (seeFigure 1) 4.2.1 General. The components of the distillation apparatus shall be connected by means of rubber bungs and tubing, or by the use of spherical ground glass jo

16、ints. NOTERubber bungs and tubing should be replaced when they begin to perish or show signs of wear. The apparatus comprises the items listed in4.2.2 to4.2.5. 4.2.2 Flask, either a round-bottomed flask,1000mL, or a Kjeldahl flask,800mL. 4.2.3 Single-bulb splash head and separate open-top dropping f

17、unnel,100mL, followed by a delivery tube at the outlet. NOTEInformation on splash heads is given in BS6855. 4.2.4 Allihn condenser, seven-bulb, with an expansion bulb of capacity approximately100mL, followed by a delivery tube at the outlet (seeBS5922). 4.2.5 Receiver, either a conical flask or beak

18、er,500mL. 4.3 Burette, classA,50mL, complying with BS846. 4.4 One-mark volumetric flask, classA,500mL, complying with BS1792. 4.5 One-mark pipette, classA, 25mL, complying with BS1583. 5 Procedure 5.1 Test portion and preparation of the test solution Weigh5.000g of the test sample and transfer to th

19、e one-mark volumetric flask (4.4). Dissolve in water, dilute to the mark and mix well. Filter through a dry filter paper, discarding the first50mL of filtrate. 5.2 Determination 5.2.1 Distillation. Transfer25.0mL of the test solution (5.1) to the flask (4.2.2) and add about250mL of water. Assemble t

20、he apparatus as shown inFigure 1. By means of a burette (4.3) measure into the receiver(4.2.5)50.0mL of the standard volumetric sulphuric acid solution (3.5). Add four or five drops of the indicator solution 3.6 a) or b) and place the receiver so that the end of the delivery tube (see4.2.4) is below

21、 the surface of the acid, adding water to the receiver if necessary.BS4267-1:1988 2 BSI 10-1999 Pour 15 mL of the sodium hdyroxide solution (3.3) into the dropping funnel (4.2.3), and carefully run all but about2mL of this solution into the distillation flask (4.2.2). Close the stopcock, leaving the

22、 remaining2mL in the dropping funnel. Bring the contents of the flask to the boil, increasing the rate of heating progressively until the contents of the flask are boiling briskly. When at least150mL of distillate has collected, partially withdraw the receiver so that the delivery tube rests on the

23、rim of the receiver. Test the subsequent distillate with the pH indicator paper(3.7) to ensure that all the ammonia has completely distilled. Remove the source of heat. Detach the splash head from the condenser (4.2.4) and wash the insides of the condenser and expansion bulb with water, collecting t

24、he washings in the receiver. Rinse the outside of the delivery tube and collect the rinsings in the receiver. 5.2.2 Titration. Back-titrate the excess of acid with the standard volumetric sodium hydroxide solution(3.4) to the neutral colour of the indicator. 5.3 Blank test Carry out a blank test at

25、the same time as the determination, using the same reagents but omitting the test solution (5.1). The result of the blank test should not exceed0.5mL of the standard volumetric sulphuric acid solution (3.5). If the result is greater than0.5mL, check the reagents by repeating the procedure described

26、inclause5, using fresh reagents as necessary. 5.4 Check test Carry out a periodic check on the efficiency of the apparatus and the accuracy of the method using an aliquot portion of a freshly prepared solution of the ammonium nitrate (3.2) containing0.05g of ammoniacal nitrogen. The check shall be m

27、ade using the same conditions as for the determination and using the same indicator. 6 Expression of results The ammoniacal nitrogen content, expressed as a percentage by mass of nitrogen (N), is given by the expression 7 Test report The test report shall include the following information: a) a comp

28、lete identification of the sample; b) a reference to this British Standard, i.e.BS4267-1:1988; c) the results expressed in accordance with clause6; d) any unusual features noted during the determination; e) any operation not included in this Part of BS4267 or regarded as optional. where V 1 is the v

29、olume of the sulphuric acid solution(3.5) used for the determination (inmL), i.e.50mL; V 2 is the volume of the sodium hydroxide solution (3.4) used for the determination (in mL); V 3 is the volume of the sulphuric acid solution (3.5) used for the blank test (inmL), i.e.50mL; V 4 is the volume of th

30、e sodium hydroxide solution (3.4) used for the blank test (in mL); V 5 is the volume of the test solution, before filtering (see5.1) (in mL), i.e.500mL; V 6 is the volume of the aliquot portion taken from the test solution (see5.2.1) (in mL), i.e.25mL; m is the mass of the test portion (see5.1) (in

31、g), i.e.5.0. This expression reduces to the following. (V 4 V 2 ) 0.56BS4267-1:1988 BSI 10-1999 3 Figure 1 Typical distillation apparatus (using a round bottomed flask)4 blankBS4267-1:1988 BSI 10-1999 Publications referred to BS 846, Specification for burettes. BS 1583, Specification for one-mark pi

32、pettes. BS 1792, Specification for one-mark volumetric flasks. BS 3591, Specification for industrial methylated spirits. BS 3978, Specification for water for laboratory use. BS 4267, Ammonium nitrate. BS 4267-0, General introduction. BS 5551, Fertilizers 1) . BS 5551-4.1.2, Determination of ammoniac

33、al nitrogen, titrimetric method after distillation. BS 5922, Specification for glass condensers for laboratory use. BS 6855, Recommendations for design and construction of glass splash heads for laboratory use. ISO 5314, Fertilizers Determination of ammoniacal nitrogen content Titrimetric method aft

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