1388/8 (TSO International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEXAYHAPOAHAR OPrAHW3ALMA HO CTAHAAPTM3AUWW+ORGANISATION INTE RNATIONALE DE NORMALISATION ANSI ImiGr? Ethanol for industrial use - Methods of test - Part 8 : Determination 'of methanol content [methanol contents between 0,10 and 1,50 % (V/ V)l -- Visual colorimetric method Ethanol a usage industriel - Methodes d'essai - Partie 8 : Dosage du methanol [teneurs de 0,10 a 1,50 % (V/V)) -- Methode colorimétrique visuelle First edition - 1981-11-01 UDC 661.722 : 543.432 : 547.261 Ref. No. 1SO 1388/8-1981 (E) 1388/8-1981 Descriptors : industrial products, ethanols, tests, determination of content, carbinols, cotorimetric analysis OS Price based on 3page from IHS Not for Resale Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards institutes (iso member bodies). The work of developing Inter- national Standards is carried out through ISO technical committees. Every member body interested in a subject for which a technical committee has been set up 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 ISO Council. International Standard ISO 1388/8 was developed by Technical Committee ISO/TC 47, Chemistry, and was circulated to the member bodies in February 1980. It has been approved by the member bodies of the following countries : Germany, F.R. Australia Romania Austria Hungary South Africa, Rep. of Belgium India Switzerland Brazil Italy Thailand Bulgaria Korea, Rep. of United Kingdom China Netherlands USSR Czechoslovakia Philippines Poland France No member body expressed disapproval of the document. International Standards ISO 1388/1 to ISO 1388/12 cancel and replace iSO Recom- mendation R 1388-1970, of which they constitute a technical revision. @International Organization for Standardization, 1981 Printed in Switzerland Copyright International Organization for Standardization from IHS Notfor Res INTERNATIONAL STANDARD ISO 1388/8-1981 (E) Ethanol for industrial use - Methods of test Part 8 : Determination of methanol content Lmethanol contents between 0,10 and 1,50 % (V/V)1 --- Visual colorimetric method 1 Scope and field of application 3.3.1 Preparation This part of ISO 1388 specifies a visual colorimetric method for Place 1 500 ml of water in a 3 000 ml conical flask, add the determination of the methanol content of ethanol for in- 4,500 ± 0,005 g of p-rosaniline hydrochloride (basic fuchsin) dustrial use. and swirl to dissolve. Add 9,6 ± 0,05 g of disodium disulphite [sodium metabisulphite (Na2S20g)], mix, and allow to stand for The method is applicable to products having methanol con- 5 to 10 min. Add 40 ml of approximately 295 g/l sulphuric acid tents between 0,10 and 1,50 % (V/ V). solution, mix thoroughly, stopper the flask and allow to stand This document should be read in conjunction with ISo 1388/1 for about 12 h. Decolorize the solution, if necessary, by treat- ment with activated carbon. (see the annex). 3.3.2 Determination and adjustment of free sulphur Principle dioxide content Conversion of the methanol present in a test portion to for Transfer 10 ml of the colourless reagent (3.3.1) to a 250 ml con- maldehyde by oxidation with a solution of potassium per- ical flask. Add 20 ml of water and 5 ml of freshly prepared manganate in phosphoric acid. Reaction of the formaldehyde starch solution and titrate the solution with standard volumetric formed with Schiff reagent. Visual comparison of the colour iodine solution, c(1/2 12) = 0,1 mol/l, until the characteristic obtained with the colours of standard colorimetric solutions dark blue colour is just obtained. containing known quantities of formaldehyde. N