1388/8 International Standard (ISO INTERNATIONAL ORGANIZATION FOR STANDARDIZATION+MEKAYHAPOAHAR OPAHM3AUMA NO CTAHAAPTM3AUWM+ORGANISATION INTERNATIONALE DE NORMALISATION ANSmG Ethanolforindustrial use- Methods oftest Part 8 : Determination of methanol content [methanol contents between 0,10 and 1,50 % (V/ V)) - Visual colorimetric method Ethanolausage industriel-Methodes d'essai-Partie8:Dosageduméthanol [teneurs de 0,10a1,50%(V/V))-Methode colorimétriquevisuelle First edition-1981-11-01 SO1388/8-1981 (E) UDC 661.722 :543.432 : 547.261 Ref.No.1SO1388/8-1981(E) Descriptors : industrial products, ethanols, tests, determination of content, carbinols, colorimetric analysis. Price based on 3 pages 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 bodyinterested ina subjectforwhichatechnical committeehasbeen set uphas the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with Iso, also take part in the work. DraftInternational Standards adoptedbythetechnical committeesarecirculatedto the member bodies for approval before their acceptance as International Standards by the ISo Council. International StandardISO1388/8wasdevelopedbyTechnicalCommitteeISO/TC47, Chemistry,and was circulated to the member bodies in February1980. Australia Germany, F.R. Romania Austria Hungary SouthAfrica, Rep, of Belgium India Switzerland Brazil Italy Thailand Bulgaria Korea, Rep. of United Kingdom China Netherlands USSR Czechoslovakia Philippines France Poland Nomemberbody expresseddisapproval of thedocument. International Standards ISo1388/1to ISo 1388/12 cancel and replaceiSORecom- mendation R 1388-1970, of which they constitute a technical revision. InternationalOrganizationforStandardization,1981 Printed in Switzerland INTERNATIONALSTANDARD ISO1388/8-1981(E) 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 1 Scopeandfieldofapplication 3.3.1 Preparation This part of ISo 1388 specifies a visual colorimetric method for Place 1500 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 (Na2S2Og)], 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/I sulphuric acid tents between 0,10 and 1,50 % (V/V). solution, mix thoroughly, stopper the fiask and allow to stand This document should be read in conjunction with ISo 1388/1 for about 12h.Decolorize the solution,if necessary,bytreat- (see the annex). ment with activated carbon. 3.3.2 Determination and adjustment of free sulphur 2Principle 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(1/2l2)= 0,1mol/l,until the characteristic obtained with the colours of standard colorimetric solutions dark blue colour is just obtained. containing known quantities of formaldehyde. NOTE - 1 ml of iodine solution, c(1/2 12) = 0,1 mol/l, corresponds to Reagents 3 0,003 2 g of S02: During the analysis, use only reagents of recognized analytical if the free sulphur dioxide content does not fall within the optimum grade, and distilled water or water of e