1、BRITISH STANDARD CONFIRMED MAY1991 BS3762-3.21: 1986 ISO8215:1985 Analysis of formulated detergents Part 3: Quantitative test methods Section 3.21 Method for determination of total silica content ISO title: Surface active agents Washing powders Determination of total silica content Gravimetric metho
2、d NOTEIt is recommended that this Section be read in conjunction with the information in the “General Introduction”, published separately as BS3762-0. UDC661.185:543BS3762-3.21:1986 This BritishStandard, having been prepared under the directionof the Chemicals Standards Committee, was published unde
3、r the authority ofthe Board of BSI and comes intoeffect on 30September1986 BSI12-1999 The committees responsible forthis BritishStandard are shown in Part0. The following BSI references relate to the work on this standard: Committee referenceCIC/34 Draft for comment84/54872DC ISBN 0 580 15328 2 Nati
4、onal foreword This Section of BS3762 has been prepared under the direction of the Chemicals Standards Committee. It is identical with ISO8215:1985 “Surface active agents Washing powders Determination of total silica content Gravimetric method”, published by the InternationalOrganization for Standard
5、ization (ISO). This method supersedes methodD12 of BS3762:1964, which has been deleted by amendment. Terminology and conventions. The text of the InternationalStandard has been approved as suitable for publication as a BritishStandard without deviation. Some terminology and certain conventions are n
6、ot identical with those used in BritishStandards; 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 baseline as the decimal marker. In BritishStandards it is current practice to use the
7、symbol “L” for litre (and in its submultiples) rather than“l”. Wherever the words “InternationalStandard” appear, referring to this standard, they should be read as “Section of this BritishStandard”. Additional information Reagents. With reference to clause4, water complying with BS3978 “Water for l
8、aboratory use” is suitable. 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 BS3762-3.21. A British Standard does not purport to inclu
9、de 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 legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi
10、 andii, pages1 and 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. Cross-reference InternationalStandard Corresponding BritishStandard ISO6
11、07:1980 BS3762 Analysis of formulated detergents Part1:1983 Methods of sample division (Identical) Amendments issued since publication Amd. No. Date of issue CommentsBS3762-3.21:1986 BSI 12-1999 i Contents Page National foreword Inside front cover 1 Scope and field of application 1 2 Reference 1 3 P
12、rinciple 1 4 Reagents 1 5 Apparatus 1 6 Sampling 1 7 Procedure 1 8 Expression of results 2 9 Test report 2 Figure Soxhlet extractor 1 Publications referred to Inside back coverii blankBS3762-3.21:1986 BSI 12-1999 1 1 Scope and field of application This InternationalStandard specifies a gravimetric m
13、ethod for the determination of the total silica content of all types of commercial washing powders, except those which contain acid-insoluble substances other than silica. 2 Reference ISO607, Surface active agents and detergents Methods of sample division. 3 Principle Removal of all the ethanol-solu
14、ble matter from a test portion by extraction with ethanol. Gravimetric determination of silica on the ethanol-insoluble fraction. 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 denatur
15、ed. 4.2 Hydrochloric acid, 1,16 to1,19g/ml. 4.3 Silver nitrate,5g/l solution. 4.4 Pumice stones, particle size2 to4mm, or equivalent as boiling aid. 5 Apparatus Ordinary laboratory apparatus and 5.1 Soxhlet extractor, with flask of capacity500ml, and extractor tube of capacity200ml (seethe Figure).
16、5.2 Glass thimble extractor, of porosityP1,6(1,64m), diameter about36mm, length about95mm. 5.3 Oven, capable of being controlled at105 2 C. 5.4 Filtering crucible, in porcelain, porosity P4(1,6 to44m). 5.5 Platinum crucible 5.6 Furnace, capable of being controlled at900 to960 C. 6 Sampling The washi
17、ng powder laboratory sample shall be prepared and stored in accordance with ISO607. 7 Procedure 7.1 Test portion Weigh, to the nearest0,01g, about10g of the laboratory sample in a600ml beaker or in the extraction thimble(5.2). 7.2 Removal of organic materials One of the two following procedures may
18、be used: 7.2.1 Soxhlet extraction Introduce300ml of the ethanol(4.1) into the500ml round-bottom flask of the Soxhlet extractor(5.1) and a few pumice stones(4.4). Place the thimble(5.2) with the test portion(7.1) in the extractor tube of the Soxhlet extractor and assemble the equipment (flask, extrac
19、tor 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. Figure Soxhlet extractorBS3762-3.21:1986 2
20、BSI 12-1999 7.2.2 Extraction by treatment 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 ins
21、oluble matter to settle. Filter the ethanolic 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(50 to60 C) to the beaker containing the insoluble matter and break an
22、y remaining hard lumps with a glass rod. Allow 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
23、. 7.3 Determination After extraction(7.2.1), remove the thimble from the Soxhlet extractor(5.1) and, using hot water(50 to75ml), 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(
24、4.2) to the beaker. Stir with a glass rod. Evaporate to dryness on a steam bath. Add35 to40ml of water. Heat, with occasional stirring, for10min. Again add10ml of the hydrochloric acid(4.2), stir and evaporate to dryness as before. Dissolve the residue, add10ml of hydrochloric acid(4.2), stir, and e
25、vaporate to dryness a third time. Place the beaker and residue in the oven(5.3), 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 through the tared porcelain filtering crucible(5.4) under vacuum o
26、r through a hardened ashless grade fast filter paper. Before taring, heat the porcelain crucible in the furnace(5.6), controlled at900 C, and allow to cool in a desiccator. Wash the residue on to the filter with hot water and continue washing until free of chlorides as shown by testing with a few dr
27、ops of the silver nitrate solution(4.3). In the case of a filter paper, place it in the platinum crucible(5.5) previously tared after heating in the furnace(5.6), controlled at900 C, and allowing to cool in a desiccator. Gradually heat the crucible and contents to900 C, then leave in the furnace(5.6
28、), controlled at900 to960 C, for30min. Allow to cool in a desiccator and weigh to the nearest0,001g. 8 Expression of results 8.1 Method of calculation The total silica content, expressed as a percentage by mass, is given by the formula 8.2 Precision Comparative analysis, on two samples containing re
29、spectively3,3%(m/m) and6,7%(m/m) of silica, carried out in nine laboratories, 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 refe
30、rence of the method used (reference to this InternationalStandard); c) the results and the method of expression used; d) the test conditions; e) any operational details not included in this InternationalStandard or in the InternationalStandard to which reference is made, or regarded as optional, as
31、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 residue. Silica content 3 to7%(m/m) Repeatability 0,15% Reproducibility 0,29% m 1 m 0 -100 BS3762-3.21:1986 BSI 12-1999 Publications referred to See
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