1、BRITISH STANDARD BS ISO 3627:2001 Photography Processing chemicals Specifications for anhydrous sodium metabisulfite ICS 37.040.30 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS ISO 3627:2001 This British Standard, having been prepared under the direction of the Consumer Pr
2、oducts and Services Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 18 January 2002 BSI 18 January 2002 ISBN 0 580 37507 2 National foreword This British Standard reproduces verbatim ISO 3627:2001 and implements it as the UK national
3、 standard. It supersedes BS ISO 3627:1994 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee CPW/42, Photography, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-re
4、ferences The British Standards which implement international publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A B
5、ritish 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. aid enquirers to understand the text; presen
6、t to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an in
7、side front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 8, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsReference number ISO 3627:2
8、001(E) OSI 1002 INTERNATIONAL STANDARD ISO 3627 Third edition 2001-12-15 Photography Processing chemicals Specifications for anhydrous sodium metabisulfite Photographie Produits chimiques de traitement Spcifications pour le mtadisulfite de sodium anhydreii ISO 3627:2001(E)iii Contents Page Foreword.
9、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.1 5 Reagents and glassware.2 6 Sampling.2 7 Test methods2 7.1 Assay 2 7.2 Mass fraction of heavy metals6 7.3 Mass fraction of iron .6 7.4 Reaction to ammonia
10、cal silver nitrate.6 7.5 pH value6 7.6 Mass fraction of thiosulfate (as S 2 O 3 2 ) 7 7.7 Appearance of solution.8 Table 1 Summary of requirements .2ISO 3627:2001(E) iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO membe
11、r 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. International organizations, governmenta
12、l 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 rules given in the ISO/IEC Directi
13、ves, 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 possibility that some of the eleme
14、nts 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 3627 was prepared by Technical Committee ISO/TC 42, Photography. This third edition cancels and replaces the second edit
15、ion (ISO 3627:1994), of which it constitutes a technical revision.ISO 3627:2001(E)v Introduction This International Standard is one of a series that establishes criteria of purity for chemicals used in processing photographic materials. General test methods and procedures cited in this International
16、 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 otherwise hazardous chemicals. Safe laboratory practice for the
17、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 shall be exercised at all times, but specific details have been provided
18、 for hazardous materials. Hazard warnings designated by a letter enclosed in angle brackets “ “ are used as a reminder in those steps detailing handling operations and are defined in ISO 10349-1. More detailed information regarding hazards, handling and use of these chemicals may be available from t
19、he 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 low as possible, consistent with these photographic effects. These
20、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 processing requirements and if there is no economic penalty in its use,
21、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 not unduly reduce the assay. All tests are performed on samples “a
22、s 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 methods described in this International Standard are generally adequate.
23、 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. Identity tests have been included whenever a possibility exists that a
24、nother 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 requirements. Efforts have been made to employ tests that are capa
25、ble 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 those cases where no other satisfactory method is available. Over the
26、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. Correlation of such alternative procedures with the given method is
27、the responsibility of the user. In case of disagreement in results, the method called for in the specification shall prevail. Where a requirement states “to pass test“, however, alternative methods shall not be used.blankINTERNATIONAL STANDARD ISO 3627:2001(E)1 Photography Processing chemicals Speci
28、fications for anhydrous sodium metabisulfite 1 Scope This International Standard establishes criteria for the purity of photographic-grade anhydrous sodium metabisulfite and specifies the tests to be used to determine the purity. 2 Normative references The following normative documents contain provi
29、sions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigat
30、e 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 applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 10349-1:1992, Photogr
31、aphy 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 content. ISO 10349-9:1992, Photography Photographic-grade chemicals Test methods Part 9: Reaction to ammoniacal silve
32、r nitrate. 3 General 3.1 Physical properties Anhydrous sodium metabisulfite (Na 2 S 2 O 5 ) exists as a white or pale-cream granular powder. It has a relative molecular mass of 190,10. 3.2 Hazardous properties Anhydrous sodium metabisulfite is not hazardous when handled with normal precautions. Avoi
33、d contact with acids. 3.3 Storage Anhydrous sodium metabisulfite shall be stored in a closed container at room temperature. 4 Requirements A summary of the requirements is shown in Table 1.ISO 3627:2001(E) 2 Table 1 Summary of requirements Test Limit Subclause International Standard in which test me
34、thod is given Assay Minimum: 95,0 % 7.1 ISO 3627 Mass fraction of heavy metals (as Pb) Maximum: 0,005 % 7.2 ISO 10349-5 Mass fraction of iron (Fe) Maximum: 0,005 % 7.3 ISO 10349-5 Reaction to ammoniacal silver nitrate To pass test 7.4 ISO 10349-9 pH value 3,7 to 4,6 7.5 ISO 3627 Mass fraction of thi
35、osulfate (as S 2 O 3 2 ) Maximum: 0,03 % 7.6 ISO 3627 Appearance of solution Clear and free from insoluble matter except for a slight flocculence 7.7 ISO 3627 5 Reagents and glassware All reagents, materials and glassware shall conform to the requirements specified in ISO 10349-1 unless otherwise no
36、ted. 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 to countr
37、y. 6 Sampling See ISO 10349-1. 7 Test methods 7.1 Assay 7.1.1 Specification The minimum mass fraction of anhydrous sodium metabisulfite shall be 95,0 %. 7.1.2 Reagents 7.1.2.1 Acetic acid, glacial,CH 3 COOH (DANGER: B C ) 1) . 7.1.2.2 Acetic acid, c(CH 3 COOH) 2mol/l. Dilute 120 g of glacial acetic
38、acid (7.1.2.1) (DANGER: B C )to1l i tr e . 1) Hazard warning codes are defined in ISO 10349-1.ISO 3627:2001(E)3 7.1.2.3 Hydrochloric acid,HCI, 1,18 g/ml (DANGER: B C ). 7.1.2.4 Potassium iodide,K I . 7.1.2.5 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 fres
39、hly sublimed iodine (DANGER: C O ) into a tared weighing flask. Add 36 g of potassium iodide (7.1.2.4) and 100 ml of water. After solution is complete, add three drops of hydrochloric acid (7.1.2.3) (DANGER: B C ) and dilute to 1 litre at 20 C in a volumetric flask. From the mass of iodine, m, calcu
40、late the concentration, c, in moles per litre, from 2 I 254 m c 7.1.2.6 Salicylic acid,H OC 6 H 4 COOH, 1 % (10 g/l) solution. 7.1.2.7 Starch indicator, 5 g/l solution. Stir 5 g of soluble starch into 100 ml of 1 % salicylic acid solution (7.1.2.6). Add 300 ml to 400 ml of boiling water. Boil until
41、the starch dissolves and dilute to 1 litre with water. 7.1.2.8 Sodium thiosulfate, c(Na 2 S 2 O 3 ) = 0,100 mol/l (15,8 g/l) 2) . NOTE This solution is not required for the direct-titration method (7.1.4.2). 7.1.2.9 Sulfuric acid, c(H 2 SO 4 ) = 0,05 mol/l (4,9 g/l) 2)4) . 7.1.2.10 Ethanol,C 2 H 5 O
42、H, 95 % (denatured). 7.1.2.11 Phenolphthalein indicator,5g/l . Dissolve 1 g of phenolphthalein in 100 ml of ethanol (7.1.2.10) and add 100 ml of water with constant stirring. Filter if necessary. 7.1.2.12 Neutral formaldehyde, HCHO, approximately 37 % (360 g/l) (DANGER: B C S ). Adjust the pH of the
43、 formaldehyde solution so that it is neutral to phenolphthalein indicator (7.1.2.11). 7.1.3 Apparatus 7.1.3.1 Burette, of capacity 50 ml. 7.1.3.2 Pipette, of capacity 50 ml. 7.1.3.3 Magnetic stirrer and bar, for direct-titration method (7.1.4.2). 2) Commercially available analysed reagent solution i
44、s recommended. If the solution is to be prepared, see any quantitative analytical chemistry test. 3) It is recommended that self-prepared iodine solutions be standardized before use. 4) This can be prepared from concentrated sulfuric acid, 1,84 g/ml (DANGER: C ).ISO 3627:2001(E) 4 7.1.4 Procedure Us
45、e either the back-titration method (7.1.4.1) or the direct-titration method (7.1.4.2). 7.1.4.1 Back-titration method Using a pipette (7.1.3.2), transfer 50,00 ml of the iodine solution (7.1.2.5) to a glass-stoppered flask. Weigh, to the nearest 0,000 1 g, a test portion of about 0,23 g and wash this
46、 into the flask. Add 5 ml of the acetic acid (7.1.2.2) and mix to ensure complete dissolution of the sample. Using a burette (7.1.3.1), titrate with the sodium thiosulfate solution (7.1.2.8), adding 2 ml of the starch indicator (7.1.2.7) just before the endpoint. Weigh, to the nearest 0,001 g, anoth
47、er test portion of about 5 g. Dissolve it in 50 ml of water and add 50 ml of the neutral formaldehyde (7.1.2.12). Add a few drops of the phenolphthalein indicator (7.1.2.11) and, using a burette (7.1.3.1), titrate with the sulfuric acid (7.1.2.9) to the colour change. 7.1.4.2 Direct-titration method
48、 Weigh, to the nearest 0,000 1 g, a test portion of about 0,12 g. Using a pipette (7.1.3.2), transfer 50,00 ml of the iodine solution (7.1.2.5) to a completely dry 250 ml beaker that contains a magnetic stirring bar (7.1.3.3). While stirring the iodine solution in the beaker, add the test portion to
49、 the centre of the beaker using a camel-hair brush. Avoid contact of the sample with the sides of the beaker. If the iodine is not decolourized after addition of the sample, discard the trial and restart the procedure. If necessary, increase the test portion by 0,01 g. Wash down the side walls of the beaker using about 2 ml of the starch indicator (7.1.2.7). Using a burette (7.1.3.1), immediately titrate with the iodine solution to the first permanent light-purple colour. Wash
