EN ISO 4048-2018 Leather - Chemical tests - Determination of matter soluble in dichloromethane and free fatty acid content.pdf

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1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Leather - Chemical tests - Determination of matter soluble in dichloromethane and free fatty acid contentBS EN ISO 4048:2018National forewordThis British Standard is the UK implementation of EN ISO 4048:2018. It is iden

2、tical to ISO 4048:2018. It supersedes BS EN ISO 4048:2008, which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee TCI/69, Footwear Clause 7 has been revised to allow analysis of a single sample, for example when too little sample is available; 8.1 has been re

3、vised to allow a smaller sample for determining only dichloromethane soluble substances; 8.2.1 and 8.3 have been revised to define a drying time of at least 6 h, and the last paragraph of 8.3 has been deleted; previous subclauses 9.1 and 9.2 have been moved to a new informative Annex B; Clause 9 has

4、 been separated into 9.1 and 9.2 and modified to allow for presenting results for a single sample;iv ISO 2018 All rights reservedBS EN ISO 4048:2018ISO 4048:2018 Clause 10 d) has been revised to allow for the changes in Clause 9. ISO 2018 All rights reserved vBS EN ISO 4048:2018This page deliberatel

5、y left blankLeather - Chemical tests - Determination of matter soluble in dichloromethane and free fatty acid content1 ScopeThis document specifies a method for the determination of the substances in leather which are soluble in dichloromethane. This method is applicable to all types of leather.Not

6、all fatty and similar substances can be extracted from leather with organic solvents; they may be in part soluble and partly bound to the leather. On the other hand, the solvent can dissolve non-fatty substances, for example sulfur and impregnants, both of which cause difficulty in the determination

7、 of the acid value and saponification value of the fat.This document includes two techniques for extraction of the fatty substances: 1) extraction using the Soxhlet apparatus; and 2) extraction using a pressurized extraction system.As the extraction is frequently done in conjunction with determinati

8、on of the free fatty acid content of the leather, a suitable procedure for determination of the free fatty acids extracted by this method is included.The apparatus and technique described in this method are also suitable for the extraction by solvents other than dichloromethane (although the tempera

9、ture conditions may need to be varied for high pressure extraction).2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated r

10、eferences, the latest edition of the referenced document (including any amendments) applies.ISO 2418, Leather Chemical, physical and mechanical and fastness tests Sampling locationISO 4044, Leather Chemical tests Preparation of chemical test samplesISO 4684, Leather Chemical tests Determination of v

11、olatile matter3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: ISO Online browsing platform: available at https:/www.iso.org/obp IEC Electropedia: a

12、vailable at http:/www.electropedia.org/3.1extractable substancesfats and other soluble matter which can be extracted from leather with dichloromethane3.2free fatty acid contentfatty acid content of the extractable substances (3.1) as determined by this method and expressed as oleic acidINTERNATIONAL

13、 STANDARDISO 4048:2018(E) ISO 2018 All rights reserved 1BS EN ISO 4048:2018ISO 4048:20184 PrincipleThe prepared leather is extracted with dichloromethane. The solvent is evaporated from the extract, which is then dried at 102 C. Subsequent analysis can then be performed on the resulting extract to d

14、etermine the free fatty acid content of the leather.5 ReagentsDuring analysis, use only reagents of a recognized analytical grade.5.1 Determination of substances soluble in dichloromethane.5.1.1 Dichloromethane, CAS No. 75-09-2.NOTE Dichloromethane which has been used for this analysis can be recove

15、red and reused after distillation.WARNING Dichloromethane has toxic properties and should be used with caution. The suppliers handling instructions should be followed.5.2 Determination of free fatty acid content of the leather.5.2.1 Mixed solvent, a mixture of equal volumes of diethyl ether and 95 %

16、 (volume fraction) ethanol, neutralized with 0,1 mol/l sodium hydroxide (phenolphthalein is used as the indicator).If, for any reason, other solvents are used, the solvent or solvents used shall be stated in the test report.5.2.2 Sodium hydroxide, 0,1 mol/l standard solution.5.2.3 Phenolphthalein in

17、dicator solution, 10 g/l prepared in 95 % (volume fraction) ethanol.In determinations on dark coloured solutions, observation of the end point of the titration may be facilitated either by the substitution of thymolphthalein or alkali blue 6B for phenolphthalein. Alternatively, 1 ml of a 0,1 % solut

18、ion of methylene blue can be added to each 100 ml of the phenolphthalein solution before titration. Phenolphthalein should be used as the preferred option if possible.6 Apparatus6.1 Soxhlet extraction apparatus, including an extraction flask of suitable capacity and a condenser, or pressurized extra

19、ction system, including extraction flask of suitable capacity, or any other validated equipment giving equivalent results to Soxhlet can be used.6.2 Filter paper thimbles, of suitable sizes, or suitable glass filter bells.6.3 Oven, capable of being maintained at (102 2) C.6.4 Analytical balance, cap

20、able of weighing to an accuracy of 0,1 mg.6.5 Desiccator, suitable for cooling the extraction vessels.6.6 Glass wool or cotton wad, or something equivalent.If a cotton wad is used, this shall be pre-extracted in dichloromethane (5.1.1).2 ISO 2018 All rights reservedBS EN ISO 4048:2018ISO 4048:20187

21、Sampling and preparation of the samplesSample in accordance with ISO 2418. If sampling in accordance to ISO 2418 is not possible, then details about sampling shall be given in the test report. Grind the leather in accordance with ISO 4044.Samples should be analysed in duplicate, if it is possible.8

22、Procedure8.1 GeneralWeigh accurately using the analytical balance (6.4) (10 0,1) g or (5 0,1) g (if only soluble matter is determined) of the prepared leather sample and press evenly into the filter paper thimble or glass bell (6.2). Cover the leather with a thin layer of glass wool or cotton wad, o

23、r equivalent (6.6).Dry the extraction flask (see 6.1) with four glass beads in it by heating for 30 min at (102 2) C. Weigh after cooling in a desiccator (6.5).If determination of free fatty acids is not being carried out, boiling chips may be used as an alternative to glass beads.Two techniques for

24、 extraction of the fatty substances are described: 1) extraction using the Soxhlet apparatus (see 8.2); and 2) extraction using a pressurized extraction system (see 8.3). In cases of dispute, the Soxhlet extraction shall be used. A comparison of results obtained using both techniques is shown in Ann

25、ex A and Annex B.8.2 Extraction using the Soxhlet apparatus8.2.1 Place the sample prepared in 8.1 into the extraction apparatus and begin continuous extraction with the dichloromethane (see 8.2.2). After at least 30 changes of solvent, distil the dichloromethane from the flask containing the extract

26、 (see 8.2.3).Dry the extract for at least 6 h in the oven (6.3), maintained at (102 2) C (if drops of water are visible before drying, add 1 ml to 2 ml of ethanol). Weigh after cooling for 30 min in a desiccator.8.2.2 Dichloromethane (5.1.1) can also dissolve non-fatty materials from the leather, fo

27、r example sulfur. (The presence of sulfur is recognizable by a yellow precipitate in the flask.) As sulfur causes difficulty, it can be removed in the following way. Dissolve the extract in the smallest possible quantity of diethyl ether and filter through a little cotton wad (6.6) into a previously

28、 weighed flask. After thoroughly washing out the cotton wad filter with ether, remove the ether from the extract in the flask by distillation over a hot water bath from which any flame has previously been removed. If the sulfur should precipitate again, repeat the procedure. After the diethyl ether

29、has been distilled off, dry the flask and residue and weigh.8.2.3 The extract may be used for analysis, for example to determine acid and saponification values of the fats, or to determine the free fatty acid content of the leather.After removal of the solvent, the extracted leather can be used for

30、determination of water soluble substances in accordance with ISO 40981. ISO 2018 All rights reserved 3BS EN ISO 4048:2018ISO 4048:20188.3 Extraction using a pressurized extraction systemPlace the sample prepared in 8.1 in the extraction apparatus and fill with dichloromethane as appropriate. The sam

31、ple should be boiled at 180 C for 40 min. Following this, sufficient dichloromethane should be distilled from the flask containing the extract to ensure that the extraction thimble is clear of the solvent. Extraction should then continue for a further 40 min, with the distilled dichloromethane perco

32、lating through the leather sample and collecting in the extraction vessel below. Finally, the remainder of the dichloromethane should be distilled from the flask containing the extract (see 8.2.2 and 8.2.3).Dry the extract for at least 6 h in the oven (6.3), maintained at (102 2) C (if drops of wate

33、r are visible before drying, add 1 ml to 2 ml of ethanol). Weigh after cooling for 30 min in a desiccator.8.4 Determination of free fatty acid contentAdd 40 ml of mixed solvent (5.2.1) to the flask containing the weighed extract obtained from 8.2 or 8.3. Add 0,5 ml of phenolphthalein indicator solut

34、ion (5.2.3) to the flask.Dissolve the extract completely by rotating the flask, warming if necessary. Cool, and rapidly titrate the solution with 0,1 mol/l sodium hydroxide solution (5.2.2), shaking vigorously during the titration, until a slight but definite colour change, persisting for 15 s, show

35、s that the end point has been reached.9 Expression of results9.1 Calculation of the matter extractable in dichloromethaneThe matter extractable in dichloromethane is given, as a percentage by mass on dry matter, by the formula:mmF10100wherem0is the mass, in grams, of the test sample;m1is the mass, i

36、n grams, of the extract;andFw=100100where w is the mass fraction of the volatile matter (in accordance with ISO 4684), in percent.The result of the matter extractable in dichloromethane is either: the mean value of the two individual determinations;or the value for a single sample.The figures shall

37、be given to one decimal place.4 ISO 2018 All rights reservedBS EN ISO 4048:2018ISO 4048:20189.2 Calculation of the free fatty acid contentThe free fatty acid content, expressed as oleic acid, C18H34O2, is given, as a percentage by mass, by the formula:VmF0282,whereV is the volume, in millilitres, of

38、 the 0,1 mol/l sodium hydroxide solution used in the titration;m0is the mass, in grams, of the test sample;F see 9.1.and 1 ml of 0,1 mol/l sodium hydroxide (5.2.2) will titrate 0,028 2 g of oleic acid.The result of the free fatty acid content is either: the mean value of the two individual determina

39、tions;or the value for a single sample.The figures shall be given to one decimal place.10 Test reportThe test report shall include the following details:a) reference to this document (i.e. ISO 4048);b) complete identification of the sample;c) the characteristics of the solvent(s) used;d) the matter

40、extractable in dichloromethane and/or the free fatty acid content as measured in 9.1 and 9.2;e) details of any deviations from the test procedure or circumstances that may have affected the results;f) details of the extraction procedure used. ISO 2018 All rights reserved 5BS EN ISO 4048:2018ISO 4048

41、:2018Annex A (informative) Comparison of five leather samplesA comparison has been carried out of five leather samples to determine if differences are observed between the pressurized extraction system and standard Soxhlet extraction.Results are illustrated in Table A.1 and are an average of triplic

42、ate analysis.Table A.1 Comparison data on five different leather samplesSample Soxhlet Pressurized solvent extractionGrease removed%Standard deviation Grease removed%Standard deviationTan 5,4 0,2 5,3 0,2Beige 3,3 0,1 3,2 0,3Light blue 10,0 0,2 9,4 0,1Dark blue 12,3 0,2 12,0 0,2Black 9,6 0,1 9,1 0,26

43、 ISO 2018 All rights reservedBS EN ISO 4048:2018ISO 4048:2018Annex B (informative) Repeatability and reproducibilityB.1 RepeatabilityThe results of duplicate determinations carried out by the same operator in the same laboratory should not differ by more than 0,2 %, calculated on the original mass o

44、f the leather.B.2 ReproducibilityThe results of two determinations carried out by different operators in different laboratories on the same sample should not differ by more than 0,5 %, calculated on the original mass of the leather. ISO 2018 All rights reserved 7BS EN ISO 4048:2018ISO 4048:2018Bibli

45、ography1 ISO 4098, Leather Chemical tests Determination of water-soluble matter, water-soluble inorganic matter and water-soluble organic matter8 ISO 2018 All rights reservedBS EN ISO 4048:2018This page deliberately left blankThis page deliberately left blankBSI is the national body responsible for

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