ISO-5400-1984.pdf

International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATlON.MEIKAYHAPOAHAR OPTAHM3AlJMR f-IO CTAHAAPTkl3ALW4ORGANlSATlON INTERNATIONALE DE NORMALISATION Leather - Determination of total silicon content - Reduced molybdosilicate spectrometric method Cuir - Dbtermina tion de la teneur en silicium total - Mthode spectromktrique au molybdosilicate rkduit First edition - 1984-03-01 UDC 675: 543.849 Ref. No. IS0 54004984 (E) Descriptors : leather, tanning, tests, determination of content, silicon, spectrophotometric analysis. Price based on 2 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 19:53:36 MDTNo reproduction or networking permitted without license from IHS -,-,- Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of developing International Standards is carried out through IS0 technical committees. Every member body interested in a subject for which a technical committee has been authorized has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. International Standard IS0 5400 was developed by Technical Committee ISO/TC 120, Leather, and was circulated to the member bodies in May 1981. It has been approved by the member bodies of the following countries : Brazil Kenya China Korea, Rep. of Egypt, Arab Rep. of Mexico Ethiopia New Zealand Germany, F. R. Romania Hungary South Africa, Rep. of India Spain Sri Lanka Tanzania Turkey United Kingdom USSR The member body technical gro unds 0 of the following country expressed disapproval of the document on France International Organization for Standardization, 1984 Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 19:53:36 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 5400-1984 (E) Leather - Determination of total silicon content - Reduced molybdosilicate spectrometric method 1 Scope and field of application This International Standard specifies a reduced molybdosilicate spectrometric method for the determination of the total silicon content of leather. It is not possible to define the chemical identity of the silicon compounds present in leather and the results are expressed in terms of the oxide Si02. Organo-silanes are present in leather and they may be determined by this procedure. Organo-silanes are almost quantitatively extracted from leather by tetra- hydrofuran or dichloromethane, and this forms the basis of a method for their determination (Elliott, JSLTC, 1964, 48, 105; SLTC-Method SLCI16). A more reliable estimate of inorganic silicon-containing compounds will therefore be obtained if leathers suspected of containing organo-silanes are first extracted with dichloromethane. 4.2 Sulfuric acid, standard solution, cW2 HZS04) = 1,0 mol/l. 4.3 Glycerol. 4.4 Sodium sulfate, 100 g/l solution. 4.5 Ammonium molybdate, 100 g/l solution containing 2 ml of ammonium hydroxide, ,020 = 0,880 g/ml, per 100 ml of solution. 4.6 Tin(ll) chloride, dihydrate, 10 g/l solution, Dissolve IO g of SnC12.2H20 in 12 ml of warm hydrochloric acid, e20 = 1,19 g/ml and 5 ml water, then dilute to 1 000 ml. Prepare this solution fresh. 2 References 4.7 Fusion mixture, consisting of IS0 835, Laboratory glassware - Graduated pipettes - Part I : General requirements. Part 2 : Pipettes for which no waiting time is specified. IS0 1042, Laboratory glassware - One-mark volumetric flasks. IS0 2418, Leather - Laboratory samples - Location and iden- tifica tion. IS0 2588, Leather - Sampling - Number of items for a gross sample. 100 g of sodium peroxide; 10 g of potassium nitrate; 3 g of powdered sucrose. 5 Apparatus Ordinary laboratory apparatus and 5.1 Parr bomb, 22 ml. IS0 4044, Leather - Preparation of chemical test samples. 5.2 Beaker, of capacity 250 ml. 3 Principle Oxidation of a test portion in a Parr bomb under alkaline condi- tions to destroy organic matter and to solubilize the mineral matter. Formation of the molybdosilicate complex and spec- trometric measurement at a wavelength of 630 nm. 4 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Concentrated sulfuric acid, g20 = 1,83 g/ml, diluted 1 + 1 with water. 5.3 One-mark volumetric flasks, of capacity 100 and 500 ml, complying with the requirements of IS0 1042. 5.4 Pipettes, complying with the requirements of IS0 835/l and IS0 835/2. 5.5 Analytical balance, accurate to 0,001 g. 5.6 Spectrometer or photo-electric absorptiometer. 5.7 pH meter, fitted with glass and reference electrodes. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 19:53:36 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 5400-1984 (E) 6 Sampling 6.1 Whole pieces of leather In the absence of any other agreement on sampling between the interested parties, use the procedure specified in IS0 2588 for sampling from a lot. Take samples from the pieces as specified in IS0 2418. 6.2 Other applications Carry out the sampling as required by the relevant specification or contract. 7 Procedure 7.1 Prepare the test sample in accordance with IS0 4044. 7.2 Place 6 g of the fusion mixture (4.7) in the Parr bomb (5.1) followed by approximately 0,5 g of the sample, weighed to an accuracy of 0,001 g. Moisten the test portion with ap- proximately 0,5 ml of the glycerol (4.3) and cover with 20 g of the fusion mixture (4.7). Seal the bomb. Place it in its protec- tion tube and warm its base with a small gas flame for 20 min. Allow to cool. Open the bomb and place it in the beaker (5.21, rinse the cover with water, collecting the rinsing water in the beaker. Add suf- ficient water to dissolve the contents of the bomb, remove it and rinse into the beaker. Transfer the beaker to a steam bath and leave for 2 h or until the hydrogen peroxide is decom- posed. Allow to cool, neutralize with the sulfuric acid solu- tion (4.1), adding a very slight excess. Transfer the solution quantitatively to the 500 ml one-mark volumetric flask (5.31, dilute to the mark and mix, to obtain the test solution. Dilute a known volume Vof the test solution containing, 0,05 to 0,2 mg of Si02 (usually 10 ml) with 40 ml of water and acidify to pH I,8 with the sulfuric acid solution (4.2). Transfer quantitatively to the 100 ml one-mark volumetric flask (5.31, add 10 ml of the ammonium molybdate solution (4.5) and allow to stand for 30 min. Add 10 ml of sulphuric acid solution (4.1), 10 ml of the tin(U) chloride solution (4.6), dilute to the mark with water and mix. Allow to stand for 30 min. Measure the blue coloration using the spectrometer or photoelectric absorptiometer (5.6) at 630 nm. The colour is stable for up to 1 h. 7.3 Prepare a calibration curve by fusing 0,l g of pure silica, weighed to the nearest 0,001 g, with sodium carbonate and making up to volume. Develop the colour in aliquots of this solution by the method described in 7.2 for the treatment of the test solution. 8 Expression of results 8.1 Calculation The total silicon content, expressed as a percentage by mass as SO, is given by the formula ml 50 -X- mo v where m0 is the mass, in grams, of the test portion; ml is the mass, in grams, of SiO, in the aliquot portion of the test solution, taken for the determination; V is the volume, in millilitres, of the test solution taken for the determination; 50 is a factor taking into account the dilutions used in the procedure. 8.2 Repeatability The results of duplicate determinations carried out by the same operator in the same laboratory shall not differ by more than 0,2 %, calculated on the original mass of leather. 8.3 Reproducibility The results of two determinations carried out by different operators in different laboratories on the same sample shall not differ by more than 0,5 %, calculated on the original mass of leather. 9 Notes on procedure 9.1 Use of leather ash The acid-insoluble residue obtained in the isolation of zirconium for analysis by hydrofluoric acid may be substituted for leather at the fusion stage. If followed, this fact should be stated in the test report. 9.2 Alternative bomb A Wurzschmitt bomb may be used in lieu of the Parr Bomb, in which case the sample size should be reduced accordingly up to and including the preparation of the test solution. 10 Test report The test report shall include the following particulars : a) reference to this International Standard; b) complete identification of the sample; c) the results obtained on the sample as received and, if required, on the basis of a standard moisture content; d) any unusual features noted during the determination; e) any operation not included in this International Stan- dard or the International Standard to which reference is made, or regarded as optional. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 19:53:36 MDTNo reproduction or networking permitted without license from IHS -,-,-