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1、BRITISH STANDARD BS 5711-22: 1979 Incorporating Amendment No. 1 Methods of Sampling and test for glycerol Part 22: Additional methods of test (non-specification) NOTEIt is recommended that this Part of BS 5711 be read in conjunction with the general information given in BS 5711-0 “General introducti
2、on”, issued separately. UDC 661.188.1:547.426.1:543.06 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:10:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-22:1979 This British Standard, having been prepared under the direction of the Chemical Standards Committee, was published under t
3、he authority of the Executive Board and comes into effect on 30 November 1979 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference CIC/6 Draft for comment 75/53579 DC ISBN 0 580 11004 4 A British Standard does not purport to include all the necessary prov
4、isions 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, pages i and ii, pages 1 to 10,
5、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 issueComments 4383October 1983Indicated by
6、 a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:10:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-22:1979 BSI 12-1999i Contents Page Section 1. General 0Introduction1 1Scope1 2References1 Section 2. Crude glycerol 3Determination of free caustic alkalinity1
7、4Determination of total alkalinity1 5Determination of carbonate alkalinity2 6Determination of acidity2 7Determination of sugars in crude and refined glycerols2 Method 1. (for iron content below 500 mg/kg)3 Method 2. (for iron content above 500 mg/kg)4 Section 3. Technical and dynamite glycerols 8Sul
8、phuric acid test5 9Determination of nitrogen content5 10Determination of diethyl ether extract7 11Determination of total chloride content7 Section 4. Reporting 12Test report8 Figure 1 Ammonia distillation apparatus9 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na
9、, Mon Dec 04 15:10:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:10:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-22:1979 BSI 12-19991 Section 1. General 0 Introduction BS 5711-1 to BS 5711-21 describe methods of sampling and
10、 test required to determine the compliance of a sample with the requirements specified for the five grades of glycerol set out in BS 2621, BS 2622, BS 2623, BS 2624 and BS 2625. There are, however, a number of test methods which, while not being required to determine compliance with the specificatio
11、n requirements, are widely used in relation to specialist applications of glycerol; for convenience these are gathered together as a single Part of this British Standard. Reference should be made to Part 2 of this British Standard for the preparation of the laboratory sample. 1 Scope This Part of BS
12、 5711 describes procedures recommended for a number of tests for glycerol other than those required to determine compliance with the requirements of British Standard specifications for glycerol, BS 2621 to BS 2625. 2 References The titles of the publications referred to in this standard are listed o
13、n the inside back cover. Section 2. Crude glycerol 3 Determination of free caustic alkalinity 3.1 Reagents. The reagents used shall be of a recognized analytical grade. Distilled water complying with the requirements of BS 3978 or water of at least equal purity and free from carbon dioxide shall be
14、used. (See Part 1 of this British Standard.) 3.1.1 Barium chloride, 100 g/l neutral solution. 3.1.2 Sulphuric acid, 0.2N standard volumetric solution. 3.1.3 Phenolphthalein indicator solution, prepared as described in BS 4123. 3.2 Apparatus 3.2.1 One-mark volumetric flask, 100 ml, complying with the
15、 requirements of BS 1792. 3.2.2 Pipette, 50 ml, complying with the requirements of BS 1583. 3.2.3 Burette, 50 ml, complying with the requirements of class A of BS 846. 3.3 Procedure. Weigh, to the nearest 0.01 g, about 20 g of the sample into the volumetric flask (3.2.1), add approximately 50 ml of
16、carbon dioxide-free water followed by an excess of the barium chloride solution (3.1.1) dilute to the mark and mix. Allow the precipitate to settle. Transfer, by means of the pipette (3.2.2), 50 ml of the clear liquid to a 250 ml conical flask, add 2 drops of the phenolphthalein indicator solution (
17、3.1.3) and titrate, using the burette (3.2.3), with the sulphuric acid solution (3.1.2). 3.4 Calculation. Calculate the free caustic alkalinity, expressed as milliequivalents per 100 g, from the formula where V is the volume of the acid used for the titration (ml) m is the mass of the test portion (
18、g). 4 Determination of total alkalinity 4.1 Reagents. The reagents used shall be of a recognized analytical grade. Distilled water complying with the requirements of BS 3978 or water of at least equal purity and free from carbon dioxide shall be used. (See Part 1 of this British Standard.) 4.1.1 Sul
19、phuric acid, 0.2N standard volumetric solution. 4.1.2 Methyl orange indicator solution, prepared as described in BS 4123. 4.2 Apparatus 4.2.1 Burette, 50 ml, complying with the requirements of class A of BS 846. 4.3 Procedure. Dissolve the ash obtained by the procedure specified in Part 6 of this Br
20、itish Standard in 50 ml of hot water in a 250 ml conical flask, cool to room temperature, add 2 drops of the methyl orange indicator solution (4.1.2) and titrate with the sulphuric acid solution (4.1.1). 4.4 Calculation. Calculate the total alkalinity, expressed as milliequivalents per 100 g, from t
21、he formula where Vis the volume of acid used for the titration (ml) mis the mass of the test portion used for the determination of the ash (g). V m - -40 V m - -20 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:10:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-22:1979 2 BSI 12-1999
22、 5 Determination of carbonate alkalinity 5.1 Reagents. The reagents used shall be of a recognized analytical grade quality. Distilled water complying with the requirements of BS 3978 or water of at least equal purity and free from carbon dioxide shall be used. (See Part 1 of this British Standard.)
23、5.1.1 Sulphuric acid, 0.2N standard volumetric solution. 5.1.2 Sodium hydroxide, 0.2N standard volumetric solution, carbonate-free, prepared as described in Appendix B of BS 5711-3 using the mass of stock solution required to make the required volume of 0.2N sodium hydroxide solution. 5.1.3 Phenolph
24、thalein indicator solution, prepared as described in BS 4123. 5.2 Apparatus 5.2.1 Burette, 50 ml, complying with the requirements of class A of BS 846. 5.2.2 Conical flask, 250 ml with ground glass socket, the neck size complying with the requirements of BS 572. 5.2.3 Condenser, water cooled, with g
25、round glass cone to fit the flask (5.2.2), complying with the requirements of BS 5922. 5.3 Procedure, Weigh, to the nearest 0.01 g, about 10 g of the sample into the 250 ml conical flask (5.2.2), add 50 ml of water followed by sufficient of the sulphuric acid solution (5.1.1), added from the burette
26、 (5.2.1), to neutralize the total alkalinity as determined by 4.2 plus an excess of 1 ml. Boil the neutralized solution under a reflux condenser (5.2.3) for 15 min to 20 min and wash down the condenser tube with carbon dioxide free water. Cool the contents of the flask rapidly, add 2 drops of the ph
27、enolphthalein indicator solution (5.1.3) and rapidly titrate the excess acid with the sodium hydroxide solution (5.1.2) using the burette (5.2.1). 5.4 Calculation 5.4.1 Calculate the free caustic and carbonate alkalinity, expressed as milliequivalents per 100 g, from the formula where 5.4.2 Calculat
28、e the carbonate alkalinity, expressed as milliequivalents per 100 g, from the formula A1 A2 where 6 Determination of acidity 6.1 Reagents. The reagents used shall be of a recognized analytical grade. Distilled water complying with the requirements of BS 3978 or water of at least equal purity and fre
29、e from carbon dioxide shall be used. (See Part 1 of this British Standard.) 6.1.1 Sodium hydroxide, 0.2N standard volumetric solution, carbonate-free, prepared as described in Appendix B of BS 5711-3 using the mass of stock solution required to make the required volume of 0.2N sodium hydroxide solut
30、ion. 6.1.2 Phenolphthalein indicator solution, prepared as described in BS 4123. 6.2 Apparatus 6.2.1 Burette, 50 ml, complying with the requirements of class A of BS 846. 6.3 Procedure. Weigh, to the nearest 0.01 g, about 10 g of the sample into a 250 ml conical flask and add 50 ml of carbon dioxide
31、 free water. Titrate with the sodium hydroxide solution (6.1.1) using 2 drops of the phenolphthalein indicator solution (6.1.3). 6.4 Calculation. Calculate the acidity, expressed as milliequivalents per 100 g, from the formula where 7 Determination of sugars in crude and refined glycerols 7.1 Princi
32、ple. Hydrolysis of an aqueous solution of the sample with mineral acid. Titrimetric determination of the total reducing sugars present in the resulting solution by means of Benedicts quantitative copper solution. V0is the volume of acid added (ml) V1is the volume of the sodium hydroxide solution use
33、d for the titration (ml) mis the mass of the test portion (g). A1is the free caustic and carbonate alkalinity (milliequivalents per 100 g), calculated as described in 5.4.1 A2is the free caustic alkalinity (milliequivalents per 100 g), determined as described in clause 3. Vis the volume of the sodiu
34、m hydroxide solution used for the titration (ml) mis the mass of the test portion (g). V m - -20 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:10:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-22:1979 BSI 12-19993 Samples having an iron content in excess of 500 mg/kg are subjected
35、 to a cation exchange process before the sugar content is determined. The method expresses the sugar content of the sample in terms of sucrose. 7.2 Method 1. Applicable to all grades of glycerol having an iron concentration below 500 mg/kg, or having a higher iron content but also a sugar content ab
36、ove 5 %. 7.2.1 Reagents. The reagents used shall be of a recognized analytical grade. Distilled water complying with the requirements of BS 3978 or water of at least equal purity and free from carbon dioxide shall be used. (See Part 1 of this British Standard.) 7.2.1.1 Benedicts quantitative copper
37、solution. Dissolve 200 g of sodium carbonate decahydrate, 200 g of trisodium citrate dihydrate and 125 g of potassium thiocyanate in 800 ml of hot water. Filter and cool. Dissolve 18 g of copper sulphate pentahydrate in about 100 ml of water and add it with constant stirring to the first solution. T
38、o this add 5 ml of a 50 g/l aqueous solution of potassium ferrocyanide trihydrate, dilute to 1 000 ml and mix. Standardize as described in 7.2.3. The reagent is stable and needs to be standardized at only very infrequent intervals. 7.2.1.2 Sulphuric acid, 0.2N standard volumetric solution. 7.2.1.3 S
39、odium hydroxide, 0.2N standard volumetric solution. 7.2.1.4 Sodium carbonate, anhydrous. 7.2.2 Apparatus 7.2.2.1 Boiling flasks, wide-necked, flat-bottomed, capacity 250 ml, complying with the requirements of BS 2734. Three flasks are required. 7.2.2.2 Flasks, one-mark volumetric, capacity 250 ml, c
40、omplying with the requirements of BS 1792. Two flasks are required. 7.2.2.3 Pipette, 20 ml, complying with the requirements of BS 1583. 7.2.2.4 Burette, 50 ml, complying with the requirements of class A of BS 846. 7.2.2.5 Soft asbestos sheet. 100 mm square and 4.5 mm to 6.0 mm thick, with a central
41、hole 38 mm in diameter. 7.2.3 Standardization of Benedicts quantitative copper solution. Weigh, to the nearest 0.001 g, about 0.5 g of sucrose into the flask (7.2.2.1). Add 40 ml of water and 2.5 ml of the sulphuric acid solution (7.2.1.2). Mix the contents of the flask, add a glass bead, boil for 3
42、 min, cool the solution, add 2.5 ml of the sodium hydroxide solution (7.2.1.3) and mix. Transfer the solution quantitatively to the volumetric flask (7.2.2.2) and dilute to the mark with water. With this solution titrate 20.00 ml of the Benedicts solution (7.2.1.1) exactly as described in 7.2.4.2. 7
43、.2.4 Procedure 7.2.4.1 Preparation of the test solution. Weigh, to the nearest 0.1 %, an amount of sample containing approximately 0.5 g of sugar into the flask (7.2.2.1). To this add 40 ml of water and 12.5 ml of the sulphuric acid solution (7.2.1.2). Mix the contents of the flask, add a glass bead
44、 and boil for 3 min. Cool the solution, add 2.50 ml of the sodium hydroxide solution (7.2.1.3) and mix. Transfer the solution quantitatively to the volumetric flask (7.2.2.2) using water and dilute to the mark. Shake and transfer a portion of the solution to the 50 ml burette (7.2.2.4). 7.2.4.2 Titr
45、ation. Transfer, by means of the pipette (7.2.2.3), 20.00 ml of the Benedicts solution (7.2.1.1) into the flask (7.2.2.1) and add 2 g of the sodium carbonate (7.2.1.4). Arrange the asbestos sheet (7.2.2.5) on a stout wire gauze over a bunsen burner and adjust the flame to give maximum heat. Place th
46、e flask centrally over the hole in the asbestos sheet, add a glass bead and allow the liquid to boil. Titrate the boiling liquid, as quickly as possible, with the test solution (7.2.4.1), taking the end of the titration as the point at which the green tint is completely discharged. Note the amount o
47、f test solution added. Titrate a second 20.00 ml portion of the Benedicts solution within a period of 2 min by adding, very quickly, a volume of the test solution to within 1 ml of the previous titration figure, bringing the mixture back to vigorous boiling before adding the final 1 ml drop by drop.
48、 Record the volume added in the second titration as the titration volume. 7.2.5 Calculation. Calculate the sugar content, expressed as a percentage by mass of sucrose, from the formula where V0is the volume of the standard sucrose solution used to titrate 20 ml of the Benedicts solution (ml) V1is th
49、e volume of the test solution used to titrate 20 ml of the Benedicts solution (ml) Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:10:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-22:1979 4 BSI 12-1999 7.3 Method 2. Applicable to all grades of glycerol having an iron content in excess of 500 mg/kg. This procedure is unnecessary for sugar contents in excess of 5 % (m/m) for which method 1 may be used. 7.3.1 Reagents. As in 7.2.1 with the addition of: 7.3.1.1 Hydrochloric acid, 5.5N reagent solution. Dilute concentrated hydrochloric acid so
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