1、BRITISH STANDARD CONFIRMED AUGUST 1993 BS 576-2:1988 Acetic acid for industrial use Part2: Methods of test for acetic acid UDC 66.061:547.292:620.1BS576-2:1988 This BritishStandard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authority ofthe
2、Board of BSI and comesintoeffect on 29January1988 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference CIC/51 Drafts for comment80/52121DC 82/54454DC ISBN 0 580 16207 9 Committees responsible for this BritishStandard The preparation of this BritishStandar
3、d was entrusted by the Chemicals Standards Committee (CIC/-) to Technical Committee CIC/51, upon which the following bodies were represented: British Pharmacopoeia Commission British Society of Perfumers Chemical Industries Association Department of Trade and Industry (Laboratory of the Government C
4、hemist) Royal Society of Chemistry Amendments issued since publication Amd. No. Date of issue CommentsBS576-2:1988 BSI 12-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Sampling and storage of sample 1 3 Measurement of colour 1 4 Determination of crystallizing
5、 point 1 5 Determination of acetic acid content 1 6 Determination of residue on evaporation on a water bath 2 7 Determination of iron content 2 8 Limit test for inorganic chlorides 2 9 Limit test for inorganic sulphates 3 10 Limit test for heavy metals (including iron) 4 11 Determination of formic a
6、cid content 4 12 Determination of acetaldehyde monomer content 7 13 Determination of total acetaldehyde content 8 14 Determination of water content 10 15 Determination of arsenic content 10 16 Test reports 10 Appendix A Relationship between BS576-2 and International Standards 11 Appendix B Relations
7、hip between crystallizing point and acetic acid content 12 Figure 1 Apparatus for determination of formic acid content 6 Figure 2 Apparatus for determination of total acetaldehyde content 9 Figure 3 Relationship between crystallizing point and acetic acid content 12 Table 1 Mass of test portion for
8、determination of acetic acid content 1 Table 2 Mass of test portion and volume of aliquot portion of test solution for limit test for inorganic chlorides 2 Table 3 Mass of test portion and volume of aliquot portion of test solution for limit test for inorganic sulphates 3 Table 4 Mass of test portio
9、n and volume of aliquot portion of test solution for limit test for heavy metals 4 Table 5 Relationship between the methods described in BS576-2 andInternational Standards describing methods of test for acetic acid 11 Table 6 Relationship between those BritishStandards describing general test method
10、s which are referred to in BS576-2 and corresponding International Standards 11 Publications referred to Inside back coverBS576-2:1988 ii BSI 12-1999 Foreword This Part of BS576 has been prepared under the direction of the Chemicals Standards Committee and provides a comprehensive series of test met
11、hods for acetic acid for industrial use. Although applicable to the material in general, it includes all the test methods required to assess compliance with BS576-1. This Part, together with BS576-1, supersedes BS576:1969, which is withdrawn. In preparing this standard, the opportunity has been take
12、n to implement various International Standards describing test methods for acetic acid. These have been prepared, with the active participation of the UK, by Technical Committee47, Chemistry, of the International Organization for Standardization (ISO), as separate Parts of ISO753 and constitute the
13、revision of ISO Recommendation R753. Appendix A gives the relationship between International Standards and this BritishStandard, together with the relationship between general test methods and corresponding International Standards. Appendix B contains a graph showing the relationship between crystal
14、lizing point and acetic acid content, based on the assumption that water is the only impurity present. This Part of BS576 specifies methods of test only and should not be used as a specification defining limits of purity. Reference to this Part of BS576 should indicate that the methods of test used
15、are in accordance with the appropriate clause(s) of BS576-2. A British Standard does not purport to include 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
16、 legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to12, 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 t
17、able on the inside front cover.BS576-2:1988 BSI 12-1999 1 1 Scope This Part of BS576 describes methods for testing acetic acid for industrial use. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Sampling and storage of sample Take a representati
18、ve sample from the bulk liquid. NOTEMethods for sampling liquid chemical products are described in BS5309-1 and BS5309-3. Store the laboratory sample in a clean, dry and airtight, ground glass stoppered bottle, or a screw-capped bottle fitted with a polyethylene cone insert, of such capacity that it
19、 is almost filled by the sample. Sufficient ullage should be left in the bottle to avoid excessive pressure changes that could arise from temperature variations during storage and handling. About10% ullage is recommended. If it is necessary to seal the bottle, take care to avoid any risk of contamin
20、ation of the contents. Store the sample in a cool place in the dark. 3 Measurement of colour Determine the colour by the method described inBS5339. 4 Determination of crystallizing point Determine the crystallizing point by the method described in BS4633, using a thermometer no. A20C/100complying wi
21、th BS593 in the inner tube. NOTEA graph showing the relationship between crystallizing point and acetic acid content is given in Appendix B. 5 Determination of acetic acid content 5.1 Principle A test portion of acetic acid is titrated with standard volumetric sodium hydroxide solution, using phenol
22、phthalein as indicator. The acid content is then calculated, making allowance for any formic acid present. 5.2 Reagents 5.2.1 General. Use only reagents of recognized analytical grade, only methylated spirits complying with BS3591, and only water complying with grade3 of BS3978. 5.2.2 Sodium hydroxi
23、de, standard volumetric solution, c(NaOH)=1mol/L. 5.2.3 Phenolphthalein, 5g/L ethanolic solution. Dissolve0.5g of phenolphthalein in100mL of95%(V/V) ethanol, or95%(V/V) industrial methylated spirits, and add4g/L sodium hydroxide solution until a pale pink coloration is obtained. NOTEThe use of indus
24、trial 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 Liquor Duties Act1979, Section10, for purposes for which industrial methylated spirits is an acceptable al
25、ternative to ethanol. 5.3 Apparatus Ordinary laboratory apparatus together with the following. 5.3.1 Weighing pipette, of capacity10mL. 5.3.2 Burette, of capacity50mL, complying with class A of BS846. 5.4 Procedure 5.4.1 Test portion. Using the weighing pipette(5.3.1), weigh, to the nearest0.0001g,
26、a mass of the laboratory sample containing2g to3g of glacial acetic acid. Suitable masses are given inTable 1. Transfer the test portion to a250mL conical flask containing50mL of water which has been boiled and cooled in a carbon dioxide-free atmosphere. Table 1 Mass of test portion for determinatio
27、n of acetic acid content 5.4.2 Determination. Add0.5mL of the phenolphthalein solution(5.2.3) to the conical flask containing the test portion(5.4.1) and titrate with the sodium hydroxide solution(5.2.2) from the burette(5.3.2) until a pink colour, which persists for about5s, is obtained. 5.5 Expres
28、sion of results The acetic acid (CH 3 COOH) content A, expressed as a percentage by mass, is given by equation: Nominal acetic acid content of laboratory sample Mass of test portion % (m/m) 98 to 100 80 60 40 g 2.5 3.0 4.0 6.0 where V is the volume (in mL) of the standard volumetric sodium hydroxide
29、 solution used for the determination; M is the mass (in g) of the test portion; F is the formic acid content, expressed as a percentage by mass, determined by the method described in clause11; A 0.060V 100 M -1.3F = 6 V M -1.3F =BS576-2:1988 2 BSI 12-1999 6 Determination of residue on evaporation on
30、 a water bath Determine the residue on evaporation by the method described in BS4524. 7 Determination of iron content 7.1 General Determine the iron content by the method described in BS6337-3 using a50mL aliquot portion of a test solution prepared as described in7.2. Calculate the result from the e
31、quation given in7.3. 7.2 Test portion and preparation of the test solution Weigh, to the nearest0.001g,40g of the laboratory sample and transfer this test portion quantitatively to a100mL one-mark volumetric flask containing about40mL of water. Dilute to the mark and mix. 7.3 Calculation of result T
32、he iron content B, expressed as a percentage by mass, is given by the equation: 8 Limit test for inorganic chlorides 8.1 Principle The turbidity obtained by adding a silver nitrate solution to a test solution, acidified with nitric acid, and the turbidity obtained from a chloride solution, of known
33、concentration, treated in the same manner are compared visually. 8.2 Reagents 8.2.1 General. Use only reagents of recognized analytical grade and only water complying with grade3 of BS3978. 8.2.2 Nitric acid, 315g/L solution. 8.2.3 Silver nitrate, 50g/L solution. 8.2.4 Standard chloride solution, co
34、ntaining0.1g of Cl per litre. Transfer28.2mL of a standard volumetric hydrochloric acid solution, c(HCl)=0.1mol/L, to a1000mL one-mark volumetric flask, dilute to the mark with water and mix. 1mL of this solution contains0.1mg of Cl . 8.3 Apparatus Ordinary laboratory apparatus together with the fol
35、lowing. 8.3.1 Filter papers, chloride-free. 8.3.2 Two matched Nessler cylinders, graduated at100mL. 8.4 Procedure 8.4.1 Test portion. Weigh (M 0.01M)g of the laboratory sample, where the value of M depends onthe limit set for the inorganic chlorides content, x%(m/m), and is given in Table 2. Table 2
36、 Mass of test portion and volume of aliquot portion of test solution for limit test for inorganic chlorides 8.4.2 Preparation of the test solution. Transfer thetest portion(8.4.1) quantitatively to a250mL one-mark volumetric flask containing approximately50mL of water. Dilute to the mark and mix. If
37、 the solution is cloudy, filter it through one of the filter papers(8.3.1). If the solution is still cloudy, carry out an extraction with a suitable solvent, for example light petroleum, to remove any wax which might be present. 8.4.3 Preparation of standard turbidimetric solution.Transfer1.0mL of t
38、he standard chloride solution(8.2.4) to one of the Nessler cylinders(8.3.2), dilute to the100mL mark with water, add2mL of the nitric acid solution(8.2.2) and mix. 8.4.4 Test. Transfer an aliquot portion of the test solution(8.4.2), as specified in Table 2, to the second Nessler cylinder(8.3.2), dil
39、ute to the100mL mark with water, add2mL of the nitric acid solution(8.2.2) and mix. 1.3 is the factor for the conversion of formic acid to acetic acid; 0.060 is the mass (in g) of acetic acid corresponding to1mL of sodium hydroxide solution, c(NaOH)=1.00mol/L. where M 1 is the mass (in g) of the tes
40、t portion; M 2 is the mass (in 4g) of iron found in the test solution; M 3 is the mass (in 4g) of iron found in the blank test solution. B 2 M 2 M 3 ()100 M 1 10 6 - = M 2 M 3 5000M 1 - = Limit for inorganic chlorides content, x Mass of test portion, M Volume of aliquot portion of test solution % (m
41、/m) Less than0.0005 0.0005 to0.05 Greater than0.05 g (50 0.0005)/x 50 (50 0.05)/x mL 100 0.05/x 1BS576-2:1988 BSI 12-1999 3 Add to each Nessler cylinder1mL of the silver nitrate solution(8.2.3) and mix. Allow the cylinders to stand in the dark for5min and then compare the turbidity produced by the a
42、liquot portion of the test solution with that produced by the standard turbidimetric solution(8.4.3). 8.5 Interpretation of results The inorganic chlorides content does not exceed the limit ofx %(m/m) of Cl if the turbidity produced by the test solution does not exceed that produced by the standard
43、turbidimetric solution. 9 Limit test for inorganic sulphates 9.1 Principle The turbidity obtained by adding a barium chloride solution to a test solution, acidified with hydrochloric acid, and the turbidity obtained from a sulphate solution, of known concentration, treated in the same manner are vis
44、ually compared. 9.2 Reagents 9.2.1 General. Use only reagents of recognized analytical grade and only water complying with grade3 of BS3978. 9.2.2 Sodium carbonate, 53g/L solution of the anhydrous salt. 9.2.3 Hydrochloric acid, 36.5g/L solution of hydrogen chloride. 9.2.4 Barium chloride dihydrate,
45、100g/L solution. 9.2.5 Standard sulphate solution, containing0.1g of SO 4 2per litre. Transfer20.8mL of a standard volumetric sulphuric acid solution, c(1/2H 2 SO 4 )=0.1mol/L, to a1000mL one-mark volumetric flask. Dilute to the mark with water and mix. 1mL of this solution contains0.1mg of SO 4 2 .
46、 9.3 Apparatus Ordinary laboratory apparatus together with the following. 9.3.1 Filter papers, sulphate-free. 9.3.2 Two matched Nessler cylinders, graduated at100mL. 9.4 Procedure 9.4.1 Test portion. Weigh (M 0.01M)g of the laboratory sample, where the value of M depends on the limit set for the ino
47、rganic sulphates content,y%(m/m), and is given in Table 3. Table 3 Mass of test portion and volume of aliquot portion of test solution for limit test for inorganic sulphates 9.4.2 Preparation of the test solution. Transfer the test portion(9.4.1) quantitatively to a porcelain evaporating dish of sui
48、table capacity. Add0.2mL of the sodium carbonate solution(9.2.2) and evaporate to dryness on a boiling water bath in a fume cupboard. Dissolve the residue in water containing1mL of the hydrochloric acid solution(9.2.3), transfer the solution quantitatively to a250mL one-mark volumetric flask, dilute
49、 to the mark with water and mix. If the solution is cloudy, filter it through one of the filter papers(9.3.1). If the solution is still cloudy, carry out an extraction with a suitable solvent, for example light petroleum, to remove any wax which might be present. 9.4.3 Preparation of standard turbidimetric solution. Transfer4.0mL of the standard sulphate solution(9.2.5) to one of the Nessler cylinders(9.3.2
