1、BRITISH STANDARD BS3762-3.8: 1986 Analysis of formulated detergents Part 3: Quantitative test methods Section 3.8 Method for determination of alkanolamides content NOTEIt is recommended that this Section be read in conjunction with the information in the “General Introduction”, published separately
2、as BS3762-0. UDC661.185:543BS3762-3.8:1986 This BritishStandard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authority ofthe Board of BSI and comesintoeffect on 30September1986 BSI 12-1999 The committees responsible forthis BritishStandard ar
3、e showninPart0. The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft for comment85/52542 DC ISBN 0 580 15327 4 Foreword This Section of BS3762 has been prepared under the direction of the Chemicals Standards Committee and supersedes method D8 of BS3762:1
4、964, which has been deleted by amendment. 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 BS3762-3.8. A British Standard does not pur
5、port 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 legal obligations. Summary of pages This document comprises a front cover, an inside front
6、cover, pagesi andii, pages1and 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. Amendments issued since publication Amd. No. Date of issue C
7、ommentsBS3762-3.8:1986 BSI 12-1999 i Contents Page Foreword Inside front cover 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Procedure 1 6 Expression of results 2 7 Precision 2 8 Test report 2 Publications referred to Inside back coverii blankBS3762-3.8:1986 BSI 12-1999 1 1 Scope This Section
8、 of BS3762 describes a method of analysis for the determination of the alkanolamides content of formulated detergents. The result is expressed as percentage alkanolamides, calculated using a stated relative molecular mass. NOTEThe titles of the publications referred to in this Section are listed on
9、the inside back cover. 2 Principle An aliquot portion of a solution of the non-ionic components, obtained in accordance with BS3762-3.7, is evaporated and then heated with sulphuric acid, sodium sulphate and selenium to convert the alkanolamides to ammonium sulphate. Ammonia is subsequently distille
10、d off and determined by titration with hydrochloric acid. NOTEThis is a form of the Kjeldahl method. 3 Reagents The reagents shall be of a recognized analytical reagent grade. Water complying with BS3978 shall be used throughout. 3.1 Ethanol NOTEFor the purposes of3.1 and 3.8, the ethanol may be rep
11、laced by industrial methylated spirits complying with BS3591, or such spirits diluted as required. It should be noted that the use of industrial 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
12、 the provisions of the Alcoholic Liquors Duties Act1972, Section10, for purposes for which industrial methylated spirits is an acceptable alternative. 3.2 Selenium 3.3 Sodium sulphate, anhydrous. 3.4 Sulphuric acid, concentrated, ( =1.84g/mL). 3.5 Orthoboric acid (boric acid),20g/L solution. Dissolv
13、e10g of orthoboric acid in water, warm if necessary to aid dissolution and dilute to500mL. 3.6 Sodium hydroxide solution, c (NaOH)=10mol/L approximately. 3.7 Hydrochloric acid, standard volumetric solution, c (HCl)=0.100mol/L. 3.8 Mixed indicator solution, comprising: a) 0.5g/L methyl red in95% (V/V
14、) ethanol; b) 1.5g/L methylene blue solution. Mix four parts ofa) with one part ofb). Prepare freshly each day. 4 Apparatus Ordinary laboratory apparatus and the following are required. 4.1 One-mark volumetric flask,100mL, complying with BS1792. 4.2 Kjeldahl flasks,50mL. 4.3 Distillation apparatus F
15、or steam distillation(5.3.1) use4.3.1 and4.3.2. For direct distillation(5.3.2) use4.3.3. 4.3.1 Semi-micro steam distillation apparatus, for example Hoskinss apparatus (80mL) 1)or Markhams apparatus (seeBS1428-B2). 4.3.2 Funnel, with long stem to reach below the ground joint of the apparatus describe
16、d in4.3.1. 4.3.3 Stillhead, with tap funnel and splash bulb, in a rubber bung or with a ground joint to fit the Kjeldahl flasks(4.2), connected to a vertical condenser. 4.4 Burette,10mL, graduated in0.02mL. 5 Procedure 5.1 Test portion Determine the non-ionic matter in accordance with BS3762-3.7. Di
17、ssolve the weighed residue in the ethanol(3.1), transfer to the100mL one-mark volumetric flask(4.1) and dilute to the mark. Pipette an aliquot portion (V mL) containing between0.10g and0.18g of non-ionic residue into the Kjeldahl flask(4.2). Alternatively, if the non-ionic residue is less than0.2g,
18、take V =50mL. If V exceeds25mL pipette in two portions, evaporating the solvent after the first. 5.2 Digestion Evaporate off the solvent. Add2g of the sodium sulphate(3.3) and0.05g of the selenium(3.2). Add4.0 0.2mL of the sulphuric acid(3.4). Place the same quantities of reagents in a second Kjelda
19、hl flask and proceed simultaneously with this blank determination. Heat the contents of the flask to boiling. Boil gently until the carbonaceous matter is “oxidized” (about20min to30min), then boil for a further20min, gradually increasing the heat, so that the acid refluxes down the walls of the fla
20、sk. Allow to cool. NOTEThe term “oxidized” has been used above in the absence of a more appropriate description. To the cool Kjeldahl flask add10mL of water, using it to rinse the walls of the flask. Swirl to dissolve the sodium sulphate. 5.3 Distillation Proceed in accordance with either5.3.1 or5.3
21、.2. 1) Hoskins, J. L. Analyst,1944,69,271.BS3762-3.8:1986 2 BSI 12-1999 5.3.1 Steam distillation. Pass steam through the semi-micro steam distillation apparatus(4.3.1), with water flowing through the condenser, for at least20min. Ensure that at least3mL/min of condensate can be produced. Empty the i
22、nner vessel of the distillation apparatus by removing the source of heat from the steam generator, then drain, and close the outlet. Unstopper the distillation apparatus, insert the funnel(4.3.2) into the inner chamber and add20 2mL of the sodium hydroxide solution(3.6). Remove the funnel, taking ca
23、re that no drop of alkali falls into the cup of the apparatus, and replace the stopper. Pass steam through the apparatus for5min to10min at a rate to produce about3mL of condensate per min. Place10mL of the orthoboric acid solution(3.5) in a100mL conical flask, add0.2mL of the mixed indicator soluti
24、on(3.8) and place the flask beneath the condenser. Raise the flask and add the minimum amount of water to ensure that the condenser tip is just covered. Pour the contents of the Kjeldahl flask into the cup of the apparatus. Without interrupting the steam supply, carefully raise the stopper and allow
25、 the solution to flow into the inner chamber at such a rate that the orthoboric acid does not rise more than20mm to30mm into the condenser. Leave a few drops of liquid in the cup to maintain a seal. Rinse the Kjeldahl flask with5mL of water, transfer to the cup, and run into the inner chamber as bef
26、ore. Repeat the rinsing. Allow distillation to continue for5min to7min, then lower the receiver and distil for a further2min to wash the inner surface of the condenser. Rinse the tip of the condenser with a little water. Continue in accordance with5.4. For an immediate subsequent determination or fo
27、r the blank determination, begin the distillation stage at paragraph2 of this clause. 5.3.2 Direct distillation. Connect the Kjeldahl flask to the stillhead and condenser(4.3.3). Place10mL of the orthoboric acid solution(3.5) into a100mL conical flask, add0.2mL of the mixed indicator solution(3.8) a
28、nd place the flask beneath the condenser. Raise the flask and add the minimum amount of water to ensure that the condenser tip is just covered. Add20 2mL of the sodium hydroxide solution(3.6) through the tap funnel into the flask, and rinse the funnel with5mL of water, maintaining a seal. Heat the c
29、ontents of the distillation flask to the boil, and boil until between one-half and two-thirds of the water present has distilled into the receiver. Lower the receiver during the distillation of the last few millimetres, then wash the tip of the condenser with water, collecting the washings in the re
30、ceiver. Continue in accordance with5.4. 5.4 Titration Titrate the contents of the receiver with the hydrochloric acid solution(3.7), using the burette(4.4). 6 Expression of results The nitrogen content, N, of the non-ionic residue, expressed as a percentage by mass, is given by the following express
31、ion: The alkanolamides content of the sample, expressed as a percentage by mass, is given by the following expression: 7 Precision No precision data are available. 8 Test report The test report shall include the following information: a) a reference to this BritishStandard, i.e.BS3762-3.8:1986; b) t
32、he results expressed in accordance with clause6; c) a complete identification of the sample. where V 1 is the volume of the hydrochloric acid solution used to titrate the sample (in mL); V 0 is the volume of the hydrochloric acid solution used to titrate the blank (in mL); m is the mass of non-ionic
33、 residue (ing) (seeBS3762-3.7); V is the volume of non-ionic solution taken (inmL). where M is the assumed relative molecular mass of the alkanolamide, e.g.243 if the result is expressed as dodecanoic ethanolamide; P is the percentage non-ionic matter in the sample (seeBS3762-3.7). V 1 V 0 ()0.1 100
34、0 - 100 V - 14 100 m - V 1 V 0 ()14 mV - = NM P 14100 -BS3762-3.8:1986 BSI 12-1999 Publications referred to BS1428, Microchemical apparatus. BS1428-B2, Ammonia distillation apparatus (Markham). BS1792, Specification for one-mark volumetric flasks. BS3591, Specification for industrial methylated spir
35、its. BS3762, Analysis of formulated detergents. BS3762-3.7, Method for determination of total non-ionic matter content. BS3978, Water for laboratory use. Analyst,1944,69,271.BS3762-3.8: 1986 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body
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