BS 6392-1-1983 Testing of ethanol for industrial use - Method for detection of alkalinity or determination of acidity to phenolphthalein《工业用乙醇试验 第1部分 碱度检测或对酚酞酸度的测定方法》.pdf

1、BRITISH STANDARD BS 6392-1: 1983 Incorporating Amendment No. 1 Testing of ethanol for industrial use Part 1: Method for detection of alkalinity or determination of acidity to phenolphthalein NOTEIt is recommended that this Part be read in conjunction with the information given in the “General introd

2、uction” published separately as BS6392-0. UDC 661.722:543.241BS6392-1:1983 This British Standard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authority ofthe Board of BSI and comesintoeffect on 31August1983 BSI 12-1999 The Committees responsi

3、ble for this British Standard are shown inPart0. The following BSI references relate to the work on this standard: Committee reference CIC/4 Draft for comment 80/51209 DC ISBN 0 580 13367 2 Foreword This Part of BS6392 is technically equivalent to ISO1388 “Ethanol for industrial use Methods of test”

4、 Part 2 “Detection of alkalinity or determination of acidity to phenolphthalein”, published in1981by the International Organization for Standardization (ISO). For ease of production, the text of ISO1388-2:1981, with the omission of the Annex, has been used for this British Standard. Some terminology

5、 and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. This standard describes

6、 a method only and should not be used as a specification defining limits of purity. Reference to the standard should indicate that the method of test used is in accordance with BS6392-1. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Stand

7、ards 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, pages i and ii, pages 1 and 2, an inside back cover and a back cover. This

8、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 Comments 4937 March 1986 Indicated by a sideline in the marginBS6392-1:1983 BSI

9、 12-1999 i Contents Page Foreword Inside front cover 1 Scope and field of application 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Procedure 1 6 Expression of results 1 Publication referred to Inside back coverii blankBS6392-1:1983 BSI 12-1999 1 1 Scope and field of application This Part of BS6392 d

10、escribes a method for the detection of alkalinity and, if appropriate, the subsequent determination of acidity of ethanol for industrial use. The method is applicable to products having acidities, expressed as acetic acid (CH 3 COOH), greater than or equal to0,0008% (m/m). NOTEThe title of the publi

11、cation referred to in this standard is given on the inside back cover. 2 Principle Dilution of a test portion with carbon dioxide-free water. Checking whether the test solution is alkaline or acid to phenolphthalein, and, if appropriate, determination of the acidity by titration with standard volume

12、tric sodium hydroxide solution. 3 Reagents During the analysis, use only reagents of recognized analytical grade and distilled water or water of equivalent purity, carbon dioxide-free, recently prepared. 3.1 Water, carbon dioxide-free. Boil distilled water and allow it to cool in a flask fitted with

13、 a stopper carrying a soda-lime guard-tube. 3.2 Sodium hydroxide, standard volumetric solution, c(NaOH)=0,1mol/l. 3.3 Phenolphthalein,5g/l ethanolic solution. Dissolve0,5g of phenolphthalein in100ml of95%(V/V) ethanol and add the sodium hydroxide solution (3.2) until a pale pink coloration is obtain

14、ed. 4 Apparatus Ordinary laboratory apparatus, and 4.1 Conical flask, of borosilicate glass, of capacity500ml, fitted with a ground glass stopper carrying a soda-lime guard-tube. 4.2 Burette, of capacity10ml, graduated in0,02ml. 5 Procedure 5.1 Test portion Take100 0,1ml of the laboratory sample. 5.

15、2 Determination Place100ml of the water (3.1) in the conical flask(4.1), add0,5ml of the phenolphthalein solution (3.3) and, if necessary, restore the pale pink coloration by the addition of a few drops of the sodium hydroxide solution (3.2). Add the test portion (5.1) and a further0,5ml of the phen

16、olphthalein solution (3.3) and note whether the solution is alkaline; if acid, titrate the test solution with the sodium hydroxide solution (3.2), stoppering the flask and swirling its contents after each addition, until a pink coloration, persisting for about15s, is obtained. Shake the contents of

17、the flask, with the stopper in position, after each addition of sodium hydroxide solution. 6 Expression of results 6.1 Alkaline products Indicate whether the product is alkaline to phenolphthalein. 6.2 Acidic products The acidity, expressed as a percentage by mass of acetic acid (CH 3 COOH), is give

18、n by the formula where NOTEIf the standard volumetric solution used is not of the exact concentration specified in the list of reagents, an appropriate correction should be applied. V is the volume, in millilitres, of the sodium hydroxide solution (3.2) used for the determination; is the density, in

19、 grams per millilitre, of the sample at20 C (seeBS4522); 0,006is the mass, in grams, of acetic acid corresponding to1ml of sodium hydroxide solution, c(NaOH)=0,100mol/l. 0,006V -2 blankBS6392-1:1983 BSI 12-1999 Publication referred to BS 4522, Method for the determination of density of liquids at 20

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