ISO-1388-5-1981.pdf

International Standard 138815 INTERNATIONAL ORGANIZATION FOR STANDARDlZATION*MEXQYHAPO,WlAR OPrAHM3AUblR fl0 CTAHAAPTH3AUHHORGANlSATlON INTERNATIONALE DE hORMALISATION i I , ! j, . * : : _ : j : n * 7. : , 8 ! Ethanol for industrial use - Methods of test - Part 5 : Determination of aldehydes content - Visual calorimetric method Ethanol B usage industriel - Mkthodes d essai - Partie 5 : Dosage des aldbhydes - M Descriptors : industrial products, ethanols, tests, determination of content, aldhehydes, calorimetric analysis. 8 2 Price based on 3 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 07:35:09 MDTNo reproduction or networking permitted without license from IHS -,-,- Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards institutes (IS0 member bodies). The work of developing Inter- national Standards is carried out through IS0 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 IS0 Council. International Standard IS0 1388/5was 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 : Australia Germany, F.R. Austria Hungary Belgium India Brazil Italy Bulgaria Korea, Rep. of China Netherlands Czechoslovakia Philippines France Poland No member body expressed disapproval of the document. Romania South Africa, Rep. of Switzerland Thailand United Kingdom USSR This International Standard has also been approved by the International Union of Pure and Applied Chemistry (IUPAC). International Standards IS0 1388/l to IS0 1388/12 cancel and replace IS0 Recom- mendation R 1388-1970, of which they constitute a technical revision. 0 International Organization for Standardization, 1981 0 Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 07:35:09 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 X388/5-1981 (E) Ethanol for industrial use - Methods of test - Part 5 : Determination of aldehydes content - Visual calorimetric method 1 Scope and field of application This part of IS0 1388 specifies a visual calorimetric method for the determination of the aldehydes content of ethanol for industrial use. The method is applicable to products having aldehyde con- tents, expressed as acetaldehyde, in the range 0,000 25 to 0,001 25 % (m/m). This document should be read in conjunction with IS0 1388/l (see the annex). 2 Principle Reaction of the aldehydes present in a test portion with Schiff reagent. Visual comparison of the colour obtained with the col- ours of standard calorimetric solutions containing known quan- tities of acetaldehyde. 3 Reagents During the analysis, use only reagents of recognized analytical grade, and distilled water or water of equivalent purity. 3.1 Ethanol, 95 % (V/v), aldehydes-free, purified as follows. Boil 1 500 ml of absolute ethanol, under reflux, for 2 h, with 15 g of m-phenylenediamine. Distil the mixture, rejecting the first and last 50 ml fractions of the distillate. Adjust the concen- tration to 95 % (V/v) by adding an appropriate volume of water and mix. Use the procedure specified in clause 5 to verify that the purified ethanol is free from aldehydes. 3.2 Schiff reagent. WARNING - Basic fuchsin is carcinogenic. Avoid skin contact with basic fuchsin and its solutions and inhala- tion of its dust. 3.2.1 Preparation Place 1 500 ml of water in a 3 000 ml conical flask, add 4,500 + 0,065 g of p-rosaniline hydrochloride (basic fuchsin), and swirl to dissolve. Add 9,60 + 0,05 g of &odium disulphite sodium metabisulphite (Na$O,)l, mix and allow to stand for 5 to 10 min. Add 40 ml of approximately 295 g/l sulphuric acid solution, mix thoroughly, stopper the flask and allow to stand for about 12 h. Decolorize the solution if necessary, by treat- ment with activated carbon. 3.2.2 Determination and adjustment of free sulphur dioxide content Transfer 10 ml of the colourless reagent (3.2.1) to a 250 ml con- ical flask. Add 20 ml of water and 5 ml of freshly prepared starch solution, and titrate the solution with standard volumetric iodine solution, c(1/2 I,) = 0,l mol/l, until the characteristic dark blue colour is just obtained. NOTE - 1 ml of iodine solution, c(1/2 12) = 0.1 mol/l, corresponds to 0,003 2 g of so2. If the free sulphur dioxide content does not fall within the op- timum range (0,18 to 0,31 g per 100 ml of reagent), adjust it as appropriate, increasing the level by adding a calculated quantity of &sodium disulphite or decreasing it by bubbling air through the reagent solution. 3.3 Acetaldehyde, standard solution corresponding to 1 g of acetaldehyde per litre. Weigh, to the nearest 0,000 1 g, 0,693 0 g of acetaldehyde am- monia CH,CH(NH2)0HI and dissolve it in the ethanol (3.1). Transfer the solution quantitatively to a 500 ml one-mark volumetric flask, dilute to the mark with ethanol of the same quality and mix. 1 ml of this standard solution contains 0,001 g of acetaldehyde. NOTE - If acetaldehyde ammonia of analytical grade is not available, purify the commercial product as follows. Dissolve about 5 g of acetaldehyde ammonia in a small quantity of ab- solute ethanol and precipitate it by adding twice the volume of dry diethyl ether (C2H50C2H5). Using a Buchner funnel, filter the precipitate and, after washing it with more of the diethyl ether, transfer it immediately to a vacuum desiccator containing sulphuric acid, Q ap- proximately 1,&M g/ml, 93 % (m/m) solution, as desiccant, and allow to dry for 3 to 4 h. Repeat the purification if necessary, until the product is colourless. WARNING - Diethyl ether is highly flammable and its vapour is harmful. Avoid breathing vapour. 3.4 Acetaldehyde, standard solution corresponding to 0,1 g of acetaldehyde per litre. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 07:35:09 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 1388/5-1981 (E) Transfer 25,0 ml of the standard acetaldehyde solution (3.3) to a 250 ml one-mark volumetric flask, dilute to the mark with the ethanol (3. I) and mix. 1 ml of this standard solution contains 0,000 1 g of acetaldehyde. 4 Apparatus Ordinary laboratory apparatus, and 4.1 Calorimetric tubes, fitted with ground glass stoppers, of capacity about 20 ml, and graduated at 10 and 14 ml. 4.2 Graduated pipettes, of capacity 5 ml, graduated in 0,02 ml divisions. 5 Procedure 5.1 Test portion Using one of the graduated pipettes (4.21, measure 3,0 ml of the laboratory sample into one of the calorimetric tubes (4.1). 5.2 Preparation of the test solution and standard calorimetric solutions Into a series of six 100 ml one-mark volumetric flasks, place the volumes of the standard acetaldehyde solution (3.4) indicated in the following table, dilute to the mark with the ethanol (3. I) and mix. Standard acetaldehyde Corresponding mass solution (3.4) of acetaldehvde ml 9 LO 0,ooo 2 3sJ 0,000 3 5.0 0,ooo 5 780 0,ooo 7 980 0,ooo 9 IO,0 0,001 0 Using the graduated pipettes (4.2), measure, into a series of six of the calorimetric tubes (4.11, 3,0 ml of each of these diluted standard acetaldehyde solutions. Treat the contents of each tube, including those of the tube containing the test portion (5.1). as follows. Dilute to 10 ml with water and add sufficient of the Schiff reagent (3.2) to bring the volume to 14 ml. Stopper the tubes, mix the solutions (preferably simultaneously) and allow to stand in a rack for 25 min. 5.3 Determination Compare the colour of the test solution with the colours of the standard calorimetric solutions, in dispersed daylight. NOTE - If the colour of the test solution is deeper than that of the most concentrated standard calorimetric solution, repeat the test using more of the laboratory sample suitably diluted with the ethanol (3.11, and take this into account in the calculation of results. 6 Expression of results The aldehydes content, expressed as acetaldehyde (CHaCHO) as a percentage by mass, is given by the formula m T where m is the mass, in grams (see the table), of acetaldehyde used to prepare the diluted standard solution giving a colour matching most closely that developed in the test solution. Q is the density, in grams per millilitre, of the sample at 20 OC (see IS0 1388/l, clause 4). 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 07:35:09 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 X388/5-1981 (E) Annex IS0 Publications relating to ethanol for industrial use IS0 1388/l - General. IS0 1388/2 - Detection of alkalinity or determination of acidity to phenolphthalein. IS0 1388/3 - Estimation of content of carbonyl compounds present in small amounts - Photometric method. IS0 1388/4 - Estimation of content of carbonyl compounds present in moderate amounts - Titrimetric method. IS0 1388/5 - Determination of aldehydes content - Visual calorimetric method. IS0 1398/6 - Test for miscibility with water. IS0 1388/7 - Determination of methanol content methanol contents between 0,Ol and 0,20 % (V/VII - Photometric method. IS0 1388/8 - Determination of methanol content methanol contents between 0,lO and I,50 % (V/v)1 - Visual calorimetric method. IS0 1388/g - Determination of esters content - Titrimetric method after saponification. IS0 1388/10 - Estimation of hydrocarbons content - Distillation method. IS0 1388/11 - Test for detection of furfural. IS0 1388112 - Determination of permanganate time. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 07:35:09 MDTNo reproduction or networking permitted without license from IHS -,-,-