1、BRITISH STANDARD CONFIRMED JUNE1993 BS3762-3.13: 1983 ISO6835:1981 Analysis of formulated detergents Part3: Quantitative test methods Section3.13 Method for determination of total boron content ISO title: Surface active agents Washing powders Determination of total boron content Titrimetric method N
2、OTEIt is recommended that this Section be read in conjunction with the information in the “General introduction”, published separately as BS3762-0. UDC 661.185:543.24:546.27BS3762-3.13:1983 This BritishStandard, having been prepared under the directionof the Chemicals Standards Committee, was publis
3、hed under the authorityofthe Board of BSI andcomes intoeffect on 30December1983 BSI 12-1999 The committees responsible for this BritishStandard are showninPart0. The following BSI references relate to the work on this standard: Committee referenceCIC/34 Draft for comment80/51140DC ISBN 0 580 13558 6
4、 Amendments issued since publication Amd. No. Date of issue CommentsBS3762-3.13:1983 BSI 12-1999 i Contents Page National foreword ii 1 Scope and field of application 1 2 References 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling 2 7 Procedure 2 8 Expression of results 2 9 Test report 3 Table
5、3 Publications referred to Inside back coverBS3762-3.13:1983 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 ISO6835:1981 “Surface active agents Washing powders Determination of total boron conte
6、nt Titrimetric method”, published by the International Organization for Standardization (ISO). This method supersedes method D2 of BS3762:1964. The original method involved isolation of the inorganic material in a test portion by low temperature ashing or by repeated extraction with95% (V/V) ethanol
7、, dissolution in water, treatment with anionic and cationic exchange resins to obtain the boric acid present in the test portion and titrimetric determination with sodium hydroxide solution in the presence of mannitol using phenolphthalein as indicator. The revised method removes silicates by adjust
8、ing the original sample solution to pH3 and filtering, and then removes anionic-active matter and phosphates by anion-exchange on a chloride form of resin. The boric acid is finally titrated potentiometrically with sodium hydroxide solution in the presence of mannitol. Terminology and conventions. T
9、he text of the International Standard has been approved as suitable for publication as a BritishStandard without deviation. Some terminology and certain conventions are not identical with those used in BritishStandards; attention is drawn especially to the following. The comma has been used as a dec
10、imal marker. In BritishStandards, it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “Section of this BritishStandard”. The Technical Committee has reviewed the provi
11、sions of ISO/R385 and ISO648, to which reference is made in clause5, and has decided that they are suitable for use in conjunction with this standard. Related BritishStandards to ISO/R385 and ISO648 are, respectively, BS846 “Specification for burettes” and BS1583 “One-mark pipettes”. Additional info
12、rmation Reagents. With reference to clause4, water complying with BS3978 “Water for laboratory use” is suitable. With reference to4.8 and its footnote, resins of this description from most chemical suppliers have been found suitable. In4.8 the term “rate of reticulation of” may be ignored and it sho
13、uld be noted that the specified particle size range150 to3004m is approximately equivalent to the now superseded designation“50100 mesh”(see Appendix C of BS410:1976 “Specification for test sieves”). Apparatus. With reference to the footnote to5.9 and5.10, many commercial types have been found suita
14、ble and are readily available. 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 BS3762-3.13. Cross-references International Standard C
15、orresponding BritishStandard ISO607:1980 BS3762 Analysis of formulated detergents Part1:1983 Methods of sample division (Identical) ISO1042:1981 BS1792:1982 Specification for one-mark volumetric flasks (Identical)BS3762-3.13:1983 BSI 12-1999 iii A British Standard does not purport to include all the
16、 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 toiv, pag
17、es1 to4, 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.iv blankBS3762-3.13:1983 BSI 12-1999 1 1 Scope and field of application This Internati
18、onal Standard specifies a titrimetric method for the rapid determination of the total boron content of commercial washing powders, without interference from other compounds usually present. The method may be used in the presence of sequestering agents. 2 References ISO/R385, Burettes. ISO607, Surfac
19、e active agents and detergents Methods of sample division. ISO648, Laboratory glassware One-mark pipettes. ISO1042, Laboratory glassware One-mark volumetric flasks. 3 Principle Removal of phosphates from an aqueous solution of a washing powder by passing over an ion-exchange resin, followed by forma
20、tion and titration of the boric acid-mannitol complex. 4 Reagents During the analysis, use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity. 4.1 D-mannitol 4.2 Hydrochloric acid, 100g/lsolution. Place25ml of hydrochloric acid ( 20approximately1,18g
21、/ml) in a100ml volumetric flask, dilute to volume and mix. 4.3 Hydrochloric acid, 10g/l solution. Place10ml of the hydrochloric acid solution(4.2) in a100ml volumetric flask, dilute to volume and mix. 4.4 Sodium hydroxide,100g/l solution. Dissolve10g of sodium hydroxide in water in a100ml volumetric
22、 flask, dilute to volume and mix. 4.5 Sodium hydroxide,10g/l solution. Place10ml of the sodium hydroxide solution(4.4) in a100ml volumetric flask, dilute to volume and mix. 4.6 Boric acid, solution containing0,5g of boron oxide(B 2 O 3 ) per litre. Weigh, to the nearest0,1mg,0,888g of boric acid(H 3
23、 BO 3 ), dissolve it in water in a1000ml volumetric flask and dilute to volume. 1ml of this solution corresponds to0,5mg of boron oxide. 4.7 Sodium hydroxide, standard volumetric solution, c(NaOH). 0,05mol/l. 4.7.1 Standardization By means of a pipette(5.3), place25,0ml of the boric acid solution(4.
24、6) in a150ml beaker, add75ml of water, and proceed as specified in7.2.3. 4.7.2 Calculation of concentration The concentration, c, expressed in moles of NaOH per litre, is given by the formula where V 0is the volume, in millilitres, of sodium hydroxide solution used for the titration of0,0125g of bor
25、on oxide. 4.8 Anion-exchange resin, strongly basic, (quaternary ammonium group), (Cl ) form, with a rate of reticulation of4% of divinylbenzene, and of particle size range150 to3004m. 1) 5 Apparatus Ordinary laboratory apparatus, and in particular: 5.1 Beaker, made of polyethylene, of capacity2000ml
26、. 5.2 Volumetric flasks, of capacity250 and1000ml, complying with the requirements of ISO1042. 5.3 Pipettes, of capacity25 and200ml, complying with the requirements of ISO648. 5.4 Burette, of capacity10ml, complying with the requirements of ISO/R385. 5.5 pH-meter, provided with an extended scale, ac
27、curate to0,05pH unit. 5.6 Glass electrode 5.7 Calomel electrode 5.8 Ion-exchange column, of length30cm, internal diameter1,5cm, with a reservoir of capacity75ml. The column shall be filled with the resin(4.8) to a length of22cm. 5.9 Vacuum filter, of capacity250ml. 2) 5.10 Filter medium, high retent
28、ion filter paper or equivalent. 2) 1) A suitable resin is available commercially. Details may be obtained from the Secretariat of ISO/TC91 (AFNOR) or ISO Central Secretariat. 2) Suitable apparatus is available commercially. Details may be obtained from the Secretariat of ISO/TC91 (AFNOR) or ISO Cent
29、ral Secretariat. c 0,0125 V 0 0,0348 - =BS3762-3.13:1983 2 BSI 12-1999 5.11 Mechanical stirrer 5.12 Magnetic stirrer 6 Sampling The washing 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 labora
30、tory sample. 7.2 Determination 7.2.1 Preparation of the test solution Transfer the test portion(7.1) to the beaker(5.1). Fill the1000ml volumetric flask(5.2) to volume with water at35 to40 C, and pour the water on to the test portion, allowing a few seconds for drainage. Stir vigorously, by means of
31、 the stirrer(5.11), for about3min in order to dissolve the test portion. Small quantities of insoluble silicates (and other salts) may remain undissolved. 7.2.2 Separation by anionic exchange resin By means of a pipette(5.3), transfer200ml of the test solution(7.2.1) to a250ml beaker and, using the
32、hydrochloric acid solutions(4.2 and4.3), adjust the pH to3 0,1, checking by means of the pH-meter(5.5) fitted with the glass electrode(5.6) and the calomel electrode(5.7). Transfer this solution quantitatively to the250ml volumetric flask(5.2) and dilute to volume. Transfer50ml of this solution to t
33、he vacuum filter(5.9) and filter through the filter medium(5.10); the filtrate shall be as clear as possible to avoid any subsequent blocking. Wash the filled ion-exchange column(5.8) with water until the washings are neutral. By means of a pipette(5.3), transfer25ml of the filtrate to the reservoir
34、 of the column and allow it to flow through the column at a rate of1 to1,5ml/min, collecting the eluate in a150ml tail-form beaker. Wash the column three times with25ml portions of water, allowing the water to flow at a rate of1 to1,5ml/min, and collect the washings in the beaker. Regenerate the res
35、in after each passage of the test solution by passing100ml of hydrochloric acid solution diluted(1+4), 1volume of hydrochloric acid( 20approximately1,18g/ml)+4 volumes of water, at a rate of1 to1,5ml/min, and washing with water, at the same rate, until the washings have a pH equal to or greater than
36、5. When not in use, the column should be filled with hydrochloric acid solution diluted(1+4). 7.2.3 Titration By means of the magnetic stirrer(5.10), stir the eluate in the beaker and adjust the pH to5,80 0,05, checking by means of the pH-meter(5.5) fitted with the electrodes(5.6 and5.7), using, as
37、appropriate, the hydrochloric acid solutions(4.2 and4.3), or the sodium hydroxide solutions(4.4 and4.5). Add12g of the D-mannitol(4.1). After stirring for1min, titrate with the sodium hydroxide solution(4.7), using the burette(5.4), until a pH of5,80 0,05 is obtained, measured using the normal scale
38、, then the extended scale, of the pH-meter. The volume of the sodium hydroxide solution used to return to the initial pH of5,8 corresponds to the quantity of boric acid present in the aliquot portion. 8 Expression of results 8.1 Method of calculation The boron oxide content, expressed as a percentag
39、e by mass, is given by the formula where V is the volume, in millilitres, of the sodium hydroxide solution(4.7), used for the titration of the25ml aliquot portion of the test solution(7.2.1); c is the exact concentration, in moles of NaOH per litre, of the sodium hydroxide solution(4.7); m is the ma
40、ss, in grams, of the test portion(7.1); 0,0348is the mass, in grams, of boron oxide corresponding to1ml of exactly1mol/l sodium hydroxide solution. By replacing c in the above formula by the expression given in4.7.2, one obtains the formula Vc 0,034 8 m - 1 000 200 - 250 25 - 100 Vc 174 m - = V 62,5
41、 V 0 m -BS3762-3.13:1983 BSI 12-1999 3 8.2 Precision Comparative analyses, on samples of two washing powders containing respectively10%(m/m) of perborate about2%(m/m) of B 2 O 3 and25%(m/m) of perborate about5,7%(m/m) ofB 2 O 3 carried out in eight laboratories, have given the statistical results gi
42、ven in the following Table. Table 9 Test report The test report shall include the following information: a) all information necessary for the complete identification of the sample; b) the reference of the method used (reference to this International Standard); c) the results and the method of expres
43、sion used; d) the test conditions; e) any details not specified in this International Standard or in the International Standards to which reference is made, or regarded as optional, as well as any incidents likely to have affected the results. Boron oxide content 2%(m/m) 5,7%(m/m) Standard deviation
44、 of repeatability, r 0,05 0,08 Standard deviation of reproducibility, R 0,14 0,084 blankBS3762-3.13:1983 BSI 12-1999 Publications referred to See national foreword.BS3762-3.13: 1983 ISO6835:1981 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national b
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