1、BRITISH STANDARD BS3762-3.22: 1986 ISO8214:1985 Analysis of formulated detergents Part 3: Quantitative test methods Section 3.22 Method for determination of inorganic sulphate content ISO title: Surface active agents Washing powders Determination of inorganic sulfates Gravimetric method NOTEIt is re
2、commended that this Section be read in conjunction with the information in the “General Introduction”, published separately as BS3762-0. UDC 661.185:543BS3762-3.22:1986 This BritishStandard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authori
3、tyofthe Board of BSI andcomes into effect on 30September1986 BSI 12-1999 The committees responsible for this BritishStandard are shown inPart0. The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft for comment84/54871 DC ISBN 0 580 15329 0 Amendments issu
4、ed since publication Amd. No. Date of issue CommentsBS3762-3.22:1986 BSI 12-1999 i Contents Page National foreword ii 1 Scope and field of application 1 2 Reference 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling 1 7 Procedure 2 8 Expression of results 3 9 Test report 3 Figure Soxhlet extracto
5、r 1 Publications referred to Inside back coverBS3762-3.22:1986 ii BSI 12-1999 National foreword This Section of BS3762 has been prepared under the direction of the Chemicals Standards Committee. It is identical with ISO8214:1985 “Surface active agents Washing powders Determination of inorganic sulfa
6、tes Gravimetric method”, published by the International Organization for Standardization (ISO). This method supersedes method D13 of BS3762:1964, which has been deleted by amendment. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as
7、a BritishStandard without deviation. Some terminology 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 BritishStandards, it is current practice to use a full point on the ba
8、seline as the decimal marker. In BritishStandards it is current practice to use the symbol “L” for litre (and in its submultiples) rather than “l”, and to use the spelling “sulphur”, etc., instead of “sulfur”, etc. Wherever the words “International Standard” appear, referring to this standard, they
9、should be read as “Section of this BritishStandard”. Additional information Reagents. With reference to clause4, water complying with BS3978 “Water for laboratory use” is suitable. This standard describes a method of test only and should not be referred to as a specification defining limits of purit
10、y. Reference to the standard should indicate that the method of test used is in conformity with BS3762-3.22. 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
11、Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding BritishStandard ISO 607:1980 BS 3762 Analysis of formulated detergents Part 1:1983 Methods of sample division (Identical) ISO 1042:1981 BS 1792:1982 Specification for one-mark vo
12、lumetric flasks (Identical) ISO 8215:1985 BS 3762 Analysis of formulated detergents Section3.21:1986 Method for determination of total silica content (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back c
13、over. 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.BS3762-3.22:1986 BSI 12-1999 1 1 Scope and field of application This International Standard specifies a gravimetric method for t
14、he determination of inorganic sulfates content of all types of commercial washing powders, without interference from other compounds usually present. 2 Reference ISO607, Surface active agents and detergents Methods of sample division. 3 Principle Removal of all the ethanol-soluble matter from a test
15、 portion by extraction with ethanol. In the presence of silicates, filtration after dehydration then precipitation of sulfates present in the filtrate with barium chloride. Filtration of the precipitate, washing, heating at900 C and weighing. NOTEThe residue obtained after removal of silicates may b
16、e used for the determination of total silica according to ISO8215. 4 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Ethanol, anhydrous or denatured. 4.2 Hydrochloric acid, 1,16 to1,19g/ml. 4.3 Ammonia, concen
17、trated solution. 4.4 Barium chloride dihydrate (BaCl 2 ,2H 2 O),100g/l solution. 4.5 Silver nitrate,5g/l solution. 4.6 Methyl orange,1g/l solution. 4.7 Pumice stones, particle size2 to4mm, or equivalent as boiling aid. 5 Apparatus Ordinary laboratory apparatus and 5.1 One-mark volumetric flasks, of
18、capacity1000ml, complying with the requirements of ISO1042. 5.2 Soxhlet extractor, with flask of capacity500ml, and extractor tube of capacity200ml (seethe Figure). 5.3 Glass thimble extractor, of porosity P1,6(1,64m), diameter about36mm, length about95mm; when a silicate determination is not requir
19、ed, an equivalent paper extraction thimble can be used. 5.4 Oven, capable of being controlled at105 2 C. 5.5 Filtering crucible, in porcelain, porosity P4(1,6 to44m). 5.6 Platinum crucible 5.7 Furnace, capable of being controlled at900 C. 6 Sampling The washing powder laboratory sample shall be prep
20、ared and stored in accordance with ISO607. Figure Soxhlet extractorBS3762-3.22:1986 2 BSI 12-1999 7 Procedure 7.1 Test portion Weigh, to the nearest0,01g, about10g of the laboratory sample in a600ml beaker or in the extraction thimble(5.3). 7.2 Removal of organic materials One of the two following p
21、rocedures may be used: 7.2.1 Soxhlet extraction Introduce300ml of the ethanol(4.1) into the500ml round-bottom flask of the Soxhlet extractor(5.2) and a few pumice stones(4.7). Place the thimble(5.3) with the test portion(7.1) in the extractor tube of the Soxhlet extractor and assemble the equipment
22、(flask, extractor tube, condenser). Start the extraction and continue with a fairly rapid rate of extraction for2h30min after the initial siphoning. Allow to cool, and transfer the remaining ethanol of the extractor to the flask and discard the ethanol-soluble fraction. 7.2.2 Extraction by treatment
23、 in beaker Add approximately250ml of ethanol(4.1) to the test portion(7.1). Cover with a watch-glass, heat and stir with a mechanical or magnetic stirrer until the ethanol is boiling. Continue boiling and stirring for5min. Allow the beaker to cool and the insoluble matter to settle. Filter the ethan
24、olic phase through a medium-grade filter paper. Repeat this extraction twice more with new portions of the ethanol(4.1) using the same filter paper. Add approximately75ml of the hot ethanol(50to60 C) to the beaker containing the insoluble matter and break any remaining hard lumps with a glass rod. A
25、llow the insoluble matter to settle and filter through the same filter paper. Repeat this operation twice more. Puncture the bottom of the filter paper and wash with about50ml of hot water to transfer any residue to the beaker containing the insoluble matter. 7.3 Removal of silicates After extractio
26、n(7.2.1), remove the thimble from the Soxhlet extractor(5.2) and, using hot water(50to75ml), quantitatively transfer the contents to a400ml beaker; or use the600ml beaker and alcohol-insoluble matter obtained as specified in7.2.2. Add10ml of the hydrochloric acid(4.2) to the beaker. Stir with a glas
27、s rod. Evaporate to dryness on a steam bath. Add35to40ml of water. Heat, with occasional stirring, for10min. If silica and insoluble matter are absent, proceed as specified in7.4; otherwise, continue as follows. Again add10ml of the hydrochloric acid(4.2), stir and evaporate to dryness as before. Di
28、ssolve the residue, add10ml of hydrochloric acid(4.2), stir, and evaporate to dryness a third time. Place the beaker and residue in the oven(5.4), maintained at105 2 C, for1h. Add50ml of hot water and10ml of the hydrochloric acid(4.2). Heat for10min on a steam bath, with occasional stirring. Filter
29、through the tared porcelain filtering crucible(5.5) under suction or through a fast-running hardened filter paper. Wash the residue four times with30ml portions of hot water. NOTEThe insoluble residue may be used for the determination of total silica according to ISO8215; in this case, change the fi
30、ltrate receiver at this point and continue the transference and washing of the residue as specified in ISO8215. 7.4 Determination Quantitatively transfer the filtrate and first four washings (from7.3) to a1000ml one-mark volumetric flask; or transfer the solution if silica and insoluble matter are a
31、bsent. Dilute to volume and mix. By means of a pipette, transfer an aliquot volume of the solution to a beaker, taking200ml for sulfate contents of less than6%(m/m) (calculated asNa 2 SO 4 ) and for higher contents taking a volume corresponding to a mass of barium sulfate of between0,15 and0,30g. Di
32、lute to200ml if necessary. Add four drops of the methyl orange solution(4.6) and neutralize with the ammonia solution(4.3). Add the hydrochloric acid(4.2) until just acid and then add5,0ml in excess. Heat to boiling and slowly add5ml of the barium chloride solution(4.4) while boiling. Cover with a w
33、atch-glass and boil gently for5min. Place on a steam bath for a minimum1h at70 to80 C. Test for completeness of precipitation by adding a few drops of the barium chloride solution(4.4). Filter through the tared porcelain filtering crucible(5.5) under vacuum or through an ashless grade medium or fine
34、 filter paper. Before taring, heat the porcelain crucible in the furnace(5.7), controlled at900 C, and allow to cool in a desiccator.BS3762-3.22:1986 BSI 12-1999 3 Wash the precipitate on to the filter with hot water and continue washing until free of chlorides as shown by testing with a few drops o
35、f the silver nitrate solution(4.5). In the case of a filter paper, place it in the platinum crucible(5.6), previously tared after heating in the furnace(5.7), controlled at900 C, and allowing to cool in a desiccator. Gradually heat the crucible and contents to900 C, then leave in the furnace(5.7), c
36、ontrolled at900 C, for30min. Allow to cool in a desiccator and weigh to the nearest0,001g. 8 Expression of results 8.1 Method of calculation The inorganic sulfate content, expressed as a percentage by mass of sodium sulfate (Na 2 SO 4 ), is given by the formula 8.2 Precision Comparative analysis on
37、three samples ranging from6% to15% Na 2 SO 4 , carried out in11laboratories, has given the statistical results shown in the following table. 9 Test report The test report shall include the following particulars: a) all information necessary for the complete identification of the sample; b) the refer
38、ence of the method used (reference to this International Standard); c) the results and the method of expression used; d) the test conditions; e) any operational details not included in this International Standard or in the International Standard to which reference is made, or regarded as optional, a
39、s well as any incidents likely to have affected the results. where m 0 is the mass, in grams, of the test portion(7.1); m 1 is the mass, in grams, of the barium sulfate precipitate; V is the volume, in millilitres, of the aliquot portion taken; 0,6086is the conversion factor for BaSO 4to Na 2 SO 4 .
40、 m 1 1 000 0,608 6 m 0 V -100 60 860 m 1 m 0 V - = Sulfate content (Na 2 SO 4 ), x 6 to15%(m/m) Repeatability 0,05 Reproducibility 0,20 x x4 blankBS3762-3.22:1986 BSI 12-1999 Publications referred to Seenational foreword.BS3762-3.22: 1986 ISO8214:1985 BSI 389 Chiswick High Road London W4 4AL BSIBrit
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