1、Reference number ISO 5990:2000(E) ISO 2000 INTERNATIONAL STANDARD ISO 5990 Third edition 2000-12-15 Photography Processing chemicals Specifications for potassium sulfite, 650 g/l solution Photographie Produits chimiques de traitement Spcifications relatives au sulfite de potassium en solution 650 g/
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5、iven below. ISO 2000 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs memb
6、er body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2000 All rights reservedISO 5990:2000(E) ISO 2000 All rights reserved iii Contents Page For
7、eword.iv Introduction.v 1 Scope 1 2 Normative references 1 3 General1 3.1 Physical properties1 3.2 Hazardous properties1 3.3 Storage1 4 Requirements.2 5 Reagents and glassware.2 6 Sampling.2 7 Test methods2 7.1 Assay 2 7.2 Mass fraction of heavy metals5 7.3 Mass fraction of iron .5 7.4 Reaction to a
8、mmoniacal silver nitrate.5 7.5 Specific gravity or density 5 7.6 pH value6 7.7 Mass fraction of thiosulfate (as S 2 O 3 2 ) 6 7.8 Appearance of solution.7ISO 5990:2000(E) iv ISO 2000 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of na
9、tional standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. Intern
10、ational organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the
11、rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the
12、possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 5990 was prepared by Technical Committee ISO/TC 42, Photography. This third edition ca
13、ncels and replaces the second edition (ISO 5990:1996), of which it constitutes a technical revision.ISO 5990:2000(E) ISO 2000 All rights reserved v Introduction This International Standard is one of a series that establishes criteria of purity for chemicals used in processing photographic materials.
14、 General test methods and procedures cited in this International Standard are compiled in ISO 10349-1. This International Standard is intended for use by individuals with a working knowledge of analytical techniques, which may not always be the case. Some of the procedures utilize caustic, toxic or
15、otherwise hazardous chemicals. Safe laboratory practice for the handling of chemicals requires the use of safety glasses or goggles and, in some cases, other protective apparel such as rubber gloves, face masks or aprons. Normal precautions for the safe performance of any chemical procedure must be
16、exercised at all times, but specific details have been provided for hazardous materials. Hazard warnings designated by a letter enclosed in angle brackets “ ” a r eu s e da sa reminder in those steps detailing handling operations and are defined in ISO 10349-1. More detailed information regarding ha
17、zards, handling and use of these chemicals may be available from the manufacturer. This International Standard provides chemical and physical requirements for the suitability of a photographic-grade chemical. The tests correlate with undesirable photographic effects. Purity requirements are set as l
18、ow as possible, consistent with these photographic effects. These criteria are considered to be the minimum requirements necessary to ensure sufficient purity for use in photographic processing solutions, except that if the purity of a commonly available grade of chemical exceeds photographic proces
19、sing requirements and if there is no economic penalty in its use, the purity requirements have been set to take advantage of the availability of the higher-quality material. Every effort has been made to keep the number of requirements to a minimum. Inert impurities are limited to amounts that will
20、not unduly reduce the assay. All tests are performed on samples “as received” to reflect the condition of materials furnished for use. Although the ultimate criterion for suitability of such a chemical is its successful performance in an appropriate use test, the shorter, more economical test method
21、s described in this International Standard are generally adequate. Assay procedures have been included in all cases where a satisfactory method is available. An effective assay requirement serves not only as a safeguard of chemical purity, but also as a valuable complement to the identity test. Iden
22、tity tests have been included whenever a possibility exists that another chemical or mixture of chemicals could pass the other tests. All requirements listed in clause 4 are mandatory. The physical appearance of the material and any footnotes are for general information only and are not part of the
23、requirements. Efforts have been made to employ tests that are capable of being run in any normally equipped laboratory and, wherever possible, to avoid tests that require highly specialized equipment or techniques. Instrumental methods have been specified only as alternative methods or alone in thos
24、e cases where no other satisfactory method is available. Over the past few years, great improvements have been made in instrumentation for various analyses. Where such techniques have equivalent or greater precision, they may be used in place of the tests described in this International Standard. Co
25、rrelation of such alternative procedures with the given method is the responsibility of the user. In the case of disagreement in results, the method called for in the specification should prevail. Where a requirement states “to pass test”, however, alternative methods should not be used.INTERNATIONA
26、L STANDARD ISO 5990:2000(E) ISO 2000 All rights reserved 1 Photography Processing chemicals Specifications for potassium sulfite, 650 g/l solution 1 Scope This International Standard establishes criteria for the purity of photographic-grade potassium sulfite, 650 g/I aqueous solution, and specifies
27、the tests to be used to determine the purity. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publica
28、tions do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to appl
29、ies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 10349-1:1992, Photography Photographic-grade chemicals Test methods Part 1: General. ISO 10349-5:1992, Photography Photographic-grade chemicals Test methods Part 5: Determination of heavy metals and iron c
30、ontent. ISO 10349-9:1992, Photography Photographic-grade chemicals Test methods Part 9: Reaction to ammoniacal silver nitrate. ISO 10349-11:1992, Photography Photographic-grade chemicals Test methods Part 11: Determination of specific gravity. ISO 10349-12:1992, Photography Photographic-grade chemic
31、als Test methods Part 12: Determination of density. 3 General 3.1 Physical properties Potassium sulfite (K 2 SO 3 ), 650 g/l aqueous solution, is a clear, colourless or almost colourless liquid. Potassium sulfite has a relative molecular mass of 158,27. 3.2 Hazardous properties Potassium sulfite, 65
32、0 g/l aqueous solution, is not hazardous when handled with normal precautions. Avoid contact with acids. 3.3 Storage Potassium sulfite solution shall be stored in a closed container at room temperature.ISO 5990:2000(E) 2 ISO 2000 All rights reserved 4 Requirements A summary of the requirements is sh
33、own in Table 1. Table 1 Summary of requirements Test Limit Subclause International Standard in which test method is given Assay Minimum: 44,5 % Maximum: 46,0 % 7.1 ISO 5990 Mass fraction of heavy metals (as Pb) Maximum: 0,002 % 7.2 ISO 10349-5 Mass fraction of iron (Fe) Maximum: 0,002 % 7.3 ISO 1034
34、9-5 Reaction to ammoniacal silver nitrate To pass test 7.4 ISO 10349-9 Specific gravity or density: specific gravity Minimum: 1,445 Maximum: 1,460 7.5.1 ISO 10349-11 density Minimum: 1,441 g/ml Maximum: 1,457 g/ml 7.5.2 ISO 10349-12 pH value of (1 + 9) solution 8,0 to 10,0 7.6 ISO 5990 Mass fraction
35、 of thiosulfate (as S 2 O 3 2 ) Maximum: 0,006 % 7.7 ISO 5990 Appearance of solution Clear and free from insoluble matter except for a slight flocculence 7.8 ISO 5990 5 Reagents and glassware All reagents, materials and glassware shall conform to the requirements specified in ISO 10349-1 unless othe
36、rwise noted. The hazard warning symbols, used as a reminder in those steps detailing handling operations, are defined in ISO 10349-1. These symbols are used to provide information to the user and are not meant to provide conformance with hazardous labelling requirements, as these vary from country t
37、o country. 6 Sampling See ISO 10349-1. 7 Test methods 7.1 Assay 7.1.1 Specification The mass fraction of potassium sulfite shall be between 44,5 % and 46,0 %. 7.1.2 Reagents 7.1.2.1 Hydrochloric acid (HCI), 1,18 g/ml (DANGER: B C ) 1) . 1) Hazard warning codes are defined in ISO 10349-1.ISO 5990:200
38、0(E) ISO 2000 All rights reserved 3 7.1.2.2 Potassium iodide (KI). 7.1.2.3 Iodine, c(I 2 ) = 0,05 mol/l (12,7 g/l) 2) 3) . Weigh, to the nearest 0,001 g, 12,7 g of freshly sublimed iodine (DANGER: C O ) into a tared weighing flask. Add 36 g of potassium iodide (7.1.2.2) and 100 ml of water. After so
39、lution is complete, add three drops of hydrochloric acid (7.1.2.1) (DANGER: B C ), and dilute to 1 litre at 20 C in a volumetric flask. From the mass of iodine, m, calculate the concentration, c, in moles per litre, from 254 m c 7.1.2.4 Sodium thiosulfate, c(Na 2 S 2 O 3 ) = 0,100 mol/l (15,8 g/l) 2
40、) . NOTE This solution is not required for the direct-titration method (7.1.4.3). 7.1.2.5 Salicylic acid, c(HOC 6 H 4 COOH) = 1 % (10 g/l). 7.1.2.6 Starch indicator, 5 g/l solution. Stir 5 g of soluble starch into 100 ml of 1 % salicylic acid solution (7.1.2.5). Add 300 ml of this solution to 400 ml
41、 of boiling water. Boil until the starch dissolves and dilute to 1 litre with water. 7.1.3 Apparatus 7.1.3.1 Burette, of capacity 50 ml. 7.1.3.2 Pipette, of capacity 25 ml. 7.1.3.3 Pipette, of capacity 50 ml. 7.1.3.4 Magnetic stirrer and bar, for the direct-titration method (7.1.4.3). 7.1.4 Procedur
42、e 7.1.4.1 Introduction Use either the back-titration method (7.1.4.2) or the direct-titration method (7.1.4.3). 7.1.4.2 Back-titration method Using a pipette (7.1.3.2), transfer 25,00 ml of the iodine solution (7.1.2.3) to a glass-stoppered flask. Weigh, to the nearest 0,000 1 g, a test portion of a
43、bout 0,25 g and wash this into the flask. Add 5 ml of the hydrochloric acid (7.1.2.1) (DANGER: B C ) and, using a burette (7.1.3.1), titrate with the sodium thiosulfate solution (7.1.2.4), adding 2 ml of the starch indicator (7.1.2.6) just before the endpoint. 7.1.4.3 Direct-titration method Weigh,
44、to the nearest 0,000 1 g, a test portion of 0,90 g. Using a pipette (7.1.3.3), transfer 50,00 ml of the iodine solution (7.1.2.3) to a completely dry 250 ml beaker that contains a magnetic stirring bar (7.1.3.4). While stirring the 2) Commercially available analysed reagent solution is recommended.
45、If the solution is to be prepared, see any quantitative analytical chemistry text. 3) It is recommended that self-prepared iodine solutions be standardized before use.ISO 5990:2000(E) 4 ISO 2000 All rights reserved iodine solution in the beaker, add the test portion to the centre of the beaker using
46、 a camel-hair brush. Avoid contact of the sample with the sides of the beaker. If the iodine is not decolorized after addition of the sample, discard the trial and restart the procedure. If necessary, increase the test portion by 0,10 g. Wash down the side walls of the beaker using about 2 ml of the
47、 starch indicator (7.1.2.6). Using a burette (7.1.3.1) immediately titrate with the iodine solution to the first permanent light-purple colour. Wash any iodine solution remaining on the burette tip into the solution with deionized water. If the titration exceeds 10 ml, repeat the test as this can re
48、sult in test results lower than the actual assay. Adjust the sample appropriately. 7.1.5 Expression of results 7.1.5.1 Back-titration method The assay, expressed as a percentage by mass of potassium sulfite (K 2 SO 3 ), is given by 12 7,914 50ccV m where c 1 is the actual concentration, expressed in
49、 moles per litre, of the iodine solution (7.1.2.3); c 2 is the actual concentration, expressed in moles per litre, of the sodium thiosulfate solution (7.1.2.4); V is the volume, expressed in millilitres, of the sodium thiosulfate solution used for the titration in 7.1.4.2; m is the mass, expressed in grams, of the test portion; 7,914 is the conversion factor obtained from the equivalent mass of potassium sulfite (i.e. 158,27/2) the conversion factor for millilitres
