1、BRITISH STANDARD BS3762-3.12: 1985 Analysis of formulated detergents Part3: Quantitative test methods Section3.12 Method for determination of ammonia content NOTEIt is recommended that this Section be read in conjunction with the information in the “General Introduction”, published separately as BS3
2、762-0. UDC 661.185:543.24:546.171.1BS3762-3.12:1985 This BritishStandard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authorityofthe Board of BSIandcomes into effect on 31January 1985 BSI 12-1999 The committees responsible forthis BritishStan
3、dard areshown in Part0. The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft for comment84/50243DC ISBN 0 580 14120 9 Foreword This Section of BS3762 has been prepared under the direction of the Chemicals Standards Committee and supersedes method D1 of B
4、S3762:1964. This standard describes a method of test only and should not be referred to as a specification defining limits of purity. Reference to the standard should indicate that the method of test used is in conformity with BS3762-3.12. A British Standard does not purport to include all the neces
5、sary 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. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 a
6、nd 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 amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS3762-3.12:1985 BSI
7、12-1999 i Contents Page Foreword Inside front cover 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Procedure 1 6 Expression of results 2 7 Test report 2 Publications referred to Inside back coverii blankBS3762-3.12:1985 BSI 12-1999 1 1 Scope This Section of BS3762 describes a method of analysi
8、s for the determination of ammonia content of formulated detergents. This method is unsuitable for detergents containing urea. A variation of the method is described for use when the detergent contains monoalkanolamines. NOTEThe titles of the publications referred to in this Section are listed on th
9、e inside back cover. 2 Principle The ammonia present is determined by direct distillation from an alkaline solution of the detergent and titration of the distillate collected in boric acid solution. When monoalkanolamines are present, a modified procedure is used. 3 Reagents The reagents shall be of
10、 a recognized analytical reagent quality. Water complying with the requirement of BS3978 shall be used throughout. 3.1 Zinc dust 3.2 Oleyl alcohol, technical 3.3 Silicone ester, liquid 3.4 Boric acid20 g/L solution. Dissolve10g of boric acid in water, warm if necessary to aid dissolution and dilute
11、to500mL. 3.5 Sodium hydroxide solution, c(NaOH)=8mol/L approximately. 3.6 Hydrochloric acid solution, c(HCl)=0.100mol/L. 3.7 Mixed indicator solution, comprising: a) 0.05% (m/V) methyl red in95% (V/V) ethanol, and; b) 0.15% (m/V) methylene blue solution. Mix four parts of a) with one part of b). Pre
12、pare freshly each day. 3.8 Phenolphthalein indicator,0.5% (m/V) solution in50% (V/V) ethanol. NOTEFor the purposes of 3.7 and 3.8, the ethanol may be replaced by industrial methylated spirits95% (V/V) complying with BS3591, or such spirits diluted as required. It should be noted that the use of indu
13、strial methylated spirits is governed by The Methylated Spirits Regulations, 1983 (S.I.1983 No.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 acceptable
14、 alternative. 4 Apparatus Ordinary laboratory apparatus and the following are required. 4.1 Distillation apparatus (for general method), Kjeldahl type, capacity not less than300mL. NOTEThe distillation apparatus may be fitted with a device to prevent foaming. 4.2 Distillation apparatus (for modified
15、 method, used when monoethanolamine is present), comprising: a) distillation flask, capacity250mL, three necked. In the side necks are fitted, respectively, a thermometer pocket and a tap funnel. In the centre neck is fitted a reflux condenser, and; b) receiver, Drechsel bottle, capacity250mL, with
16、its inlet connected to the top of the reflux condenser and its outlet to a filter pump. 5 Procedure 5.1 Test portion Weigh, to the nearest0.01g, an appropriate amount of the well mixed sample (usually1g to5g) into the distillation flask(4.1 or4.2). 5.2 Determination 5.2.1 General method. Add100mL of
17、 water, a pinch of zinc dust(3.1) and about5mL of oleyl alcohol(3.2) or a few drops of silicone ester to the flask and then connect it to the tap funnel and stillhead. In the receiver place50mL of the boric acid solution(3.4) and about five drops of the mixed indicator solution(3.7). By means of the
18、 tap funnel, add a few drops of the phenolphthalein indicator to the distillation flask, followed by sufficient of the sodium hydroxide solution(3.5) to render the contents alkaline and a few millilitres in excess. Keep the tap of the funnel closed except when reagents are actually being added. Heat
19、 the contents of the distillation flask to the boil, and boil until between half and two-thirds of the water present has distilled into the receiver. Wash the inner surface of the condenser and the tip with water, collecting the washings in the receiver. Titrate the contents of the receiver with the
20、 hydrochloric acid solution(3.6). The colour changes from green to grey, and then to purple with excess acid. Prepare a blank containing the same volumes of the boric acid solution, indicator, and water as for the test titration, and titrate to the same coloured end point as the test solution.BS3762
21、-3.12:1985 2 BSI 12-1999 5.2.2 Modified method (for use when monoalkanolamines are present). Proceed as in the general method (see5.2.1) but, instead of distilling the ammonia solution by boiling, heat the contents of the distillation flask to100 C and maintain at this temperature for1h while passin
22、g a slow stream of air through the apparatus. 6 Expression of results The ammonia content, expressed as a percentage by mass, is given by the following expression: 7 Test report The test report shall include the following information: a) a reference to this BritishStandard, i.e.BS3762-3.14; b) the r
23、esults and the method of expression used; c) the test conditions. where V 1 is the volume of the hydrochloric acid solution(3.6) used for the test solution (inmL); V 2 is the volume of the hydrochloric acid solution(3.6) used for the blank (in mL); c is the concentration of the hydrochloric acid sol
24、ution(3.6) (in mol/L); m is the mass of the test portion (in g). V 1 V 2 ()c 0.017 100 m -BS3762-3.12:1985 BSI 12-1999 Publications referred to BS3591, Industrial methylated spirits. BS3978, Water for laboratory use. BS3762-3.12: 1985 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInsti
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