BS-5711-16-1979.pdf

BRITISH STANDARD CONFIRMED AUGUST 1994 BS 5711-16: 1979 Methods of Sampling and test for glycerol Part 16: Determination of iron content NOTEIt is recommended that this Part of BS 5711 be read in conjunction with the general information given in BS 5711-0 “General introduction”, issued separately. UDC 661.188.1:547.426.1:543.062:546.72 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:12:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-16:1979 This British Standard, having been prepared under the direction of the Chemicals Standards Committee, was published under the authority of the Executive Board and comes into effect on 30 November 1979 © BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference CIC/6 Draft for comment 75/53579 DC ISBN 0 580 10997 6 A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:12:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-16:1979 © BSI 12-1999i Contents Page 1Scope and field of application1 2References1 3Principle1 4Reagents1 5Apparatus1 6Sampling1 7Procedure1 8Calculation2 9Test report2 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:12:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:12:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-16:1979 © BSI 12-19991 1 Scope and field of application This British Standard describes a photometric method for the determination of the iron content of technical glycerol. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Principle Dissolution of sulphated ash residues, formation of a thioglycollate complex and photometric measurement of the absorbance of the complex. 4 Reagents The reagents used shall be of recognized analytical grade. Distilled water complying with the requirements of BS 3978 or water of at least equal purity shall be used. 4.1 Potassium hydrogen sulphate, fused. 4.2 Thioglycollic acid, 10 % (m/m) reagent solution. Dilute thioglycollic acid, 90 % (m/m), 1 + 9. WARNING. Take great care not to allow concentrated thioglycollic acid to come into contact with the skin as it causes painful wounds. 4.3 Trisodium citrate dihydrate, 300 g/l reagent solution. 4.4 Hydrochloric acid, concentrated, 36 % (m/m), 11N. 4.5 Ammonia, 7N reagent solution. Dilute concentrated ammonia solution, 35 % (m/m), (18N), 1 + 1.5. 4.6 Standard iron solutions: Solution A. Dissolve 0.7023 g of pure ammonium iron (II) sulphate hexahydrate FeSO4.(NH4)2SO4.6H2O in water containing 10 ml of sulphuric acid solution, 50 % (m/m), in a 1 000 ml one-mark volumetric flask, mix well and dilute to the mark with water. 1 ml N 100 4g Fe. Solution B. Transfer 25.0 ml of solution A to a 250 ml one-mark volumetric flask and dilute to the mark with water. 1 ml N 10 4g Fe. 5 Apparatus 5.1 Volumetric flasks, one-mark, 50 ml capacity, with ground glass neck, complying with the requirements of BS 1792. 5.2 Spectrophotometer, adjusted to read at 530 nm or a photoelectric absorptiometer with a green filter transmitting from about 500 nm to 545 nm with maximum transmission at 530 nm. Cells, all glass, of such a size that the absorbance of the solution under test lies between 0.2 and 0.8. 5.3 Nessler cylinders, 50 ml capacity, complying with the requirements of BS 612. 6 Sampling Prepare the laboratory sample as described in Part 2 of this British Standard. 7 Procedure 7.1 Preparation of the calibration curve. Dissolve 2 g of potassium hydrogen sulphate in 10 ml of water and 5 ml of the hydrochloric acid solution (4.4). Add amounts of the standard iron solution (4.6) equivalent to 0, 25, 50, 75, 100 and 125 4g of iron (Fe), and proceed as described for the test solution in 7.2. Measure the absorbances in turn against the first solution containing no added iron and plot the masses of iron (Fe) against absorbances. When different cell lengths are used to obtain appropriate absorbances, the calibration results should be expressed in terms of a uniform cell length. If neither a spectrophotometer nor a photoelectric absorptiometer is available, the test solution may be compared with standard iron solutions in 50 ml Nessler cylinders (5.3), or matched against a suitable colour disc in a comparator. 7.2 Measurement. To the residue obtained in the determination of sulphated ash (see Part 7 of this British Standard), add 2 g of the potassium hydrogen sulphate (4.1), and fuse gently until a clear melt is obtained. Allow to cool, add 5 ml of the hydrochloric acid solution (4.4) and warm, flowing the acid round the sides of the dish. Add 10 ml to 15 ml of water, cover and heat on a hotplate until a clear solution is obtained. Prepare a reagent blank by dissolving 2 g of the potassium hydrogen sulphate in 5 ml of the hydrochloric acid solution and 10 ml to 15 ml of water. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:12:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-16:1979 2 © BSI 12-1999 Allow to cool, transfer quantitatively to the 50 ml one- one-mark volumetric flask (5.1) and add 2 ml of the trisodium citrate solution (4.3) and 1.0 ml of the thioglycollic acid solution (4.2) to the test solution and to the reagent blank. Make each solution slightly alkaline by adding the ammonia solution (4.2) until the pink colour of the iron complex just persists, then make just acid with the hydrochloric acid solution (4.4) (indicated by disappearance of the pink colour) and cool to room temperature. Add 2.0 ml of the ammonia solution to redevelop the pink colour and dilute to 50 ml with water. Set up the spectrophotometer or photoelectric absorptiometer (5.2) as described in 5.2. Allow the test solution and blank to stand for 5 min and transfer each to a cell (5.3) and measure the absorbance of the test solution against that of the blank in the reference cell. NOTEIt is advisable that all tests should be carried out in duplicate. 8 Calculation Read off the iron content, expressed as milligrams per kilogram, from the calibration curve. 9 Test report The test report shall include the following particulars: a) a reference to this British Standard; b) the result and the method of expression used; c) any unusual features noticed during the determination; d) any operation not included in this British Standard or regarded as optional. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:12:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-16:1979 © BSI 12-1999 Publications referred to BS 612, Nessler cylinders. BS 1792, One-mark volumetric flasks. BS 3978, Water for laboratory use. BS 5711, Methods of sampling and test for glycerol. BS 5711-2, Methods of sampling. BS 5711-7, Determination of sulphated ash: gravimetric method. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:12:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5711-16: 1979 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: 020 8996 9000. Fax: 020 8996 7400. BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services. Tel: 020 8996 9001. Fax: 020 8996 7001. In response to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested. Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help to Exporters Service. Various BSI electronic information services are also available which give details on all its products and services. Contact the Information Centre. Tel: 020 8996 7111. Fax: 020 8996 7048. Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of standards. For details of these and other benefits contact Membership Administration. Tel: 020 8996 7002. Fax: 020 8996 7001. Copyright Copyright subsists in all BSI publications. BSI also holds the copyright, in the UK, of the publications of the international standardization bodies. Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, photocopying, recording or otherwise without prior written permission from BSI. This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations. If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained. If permission is granted, the terms may include royalty payments or a licensing agreement. Details and advice can be obtained from the Copyright Manager. Tel: 020 8996 7070. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:12:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI