1、BRITISH STANDARD BS EN ISO 787-19:1995 BS3483-C9: 1995 General methods of test for pigments Part19: Determination of water-soluble nitrates(Salicylic acid method) This European Standard EN ISO787-19:1995 has the same status as a BritishStandard ICS: 87.060.10BSENISO787-19:1995 This British Standard,
2、 having been prepared under the directionof the Sector Board forMaterials and Chemicals, waspublished under the authorityof the Standards Boardand comes into effect on 15November1995 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference STI/1 Draft announc
3、ed in BSINews November1995 ISBN 0 580 24119 X Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted to Technical Committee STI/1, Pigments, upon which the following bodies were represented: British Cement Association British Coatings Federation Ltd. Br
4、itish Colour Makers Association British Precast Concrete Federation Ltd. Cement and Concrete Pigment Suppliers Association China Clay Association Oil and Colour Chemists Association Titanium Pigment Manufacturers Technical Committee Zinc Development Association Amendments issued since publication Am
5、d. No. Date CommentsBSENISO787-19:1995 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN ISO787-19 3 List of references Inside back coverBSENISO787-19:1995 ii BSI 01-2000 National foreword This BritishStandard has been prepared by Techni
6、cal Committee STI/1. It is identical with ISO787-19:1974 General methods of test for pigments Part19:Determination of water-soluble nitrates (salicylic acid method) published by the International Organization for Standardization(ISO). In1995 the European Committee for Standardization(CEN) accepted I
7、SO787-19:1974 as European Standard EN ISO787-19:1995. As a consequence of implementing the European Standard this British Standard is dual-numbered as BS EN ISO787-19:1995, BS3483-C9:1995. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Sta
8、ndards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-reference Publication referred to Corresponding BritishStandard ISO842 BS4726:1986 Methods for sampling raw materials for paints and varnishes Sum
9、mary of pages This document comprises a front cover, an inside front cover, pages i and ii, theENISOtitle page, pages2 to4, 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 tab
10、le on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO787-19 August1995 ICS 87.060.10 Descriptors: Paints, pigments, tests, chemicalanalysis, determination of content, nitrates, spectrophotometry English version General methods of test for pigments Part19: Determinatio
11、n of water-soluble nitrates (Salicylic acid method) (ISO787-19:1974) Mthodes gnrales dessai des pigments Partie19: Dtermination des nitrates solubles dans leau(Mthodes lacide salicyclique) (ISO787-19:1974) Allgemeine Prfverfahren fr Pigmente Teil19: Bestimmung der wasserlslichen Nitrate(Salicylsure-
12、Verfahren) (ISO787-19:1974) This European Standard was approved by CEN on1995-03-23. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists a
13、nd bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions(English, French, German). A version in any other language made by translation under the responsibi
14、lity of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Por
15、tugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1995 All rights of reproduction and communication in any form and by any means reser
16、ved in all countries to CEN and its members Ref. No. EN ISO787-19:1994 EENISO787-19:1995 BSI 01-2000 2 Foreword The text of the International Standard from ISO/TC35, Paints and varnishes, of the International Organization for Standardization(ISO) has been taken over as a European Standard by the Tec
17、hnical Committee CEN/TC298, Pigments and extenders. This European Standard shall be given the status of a National standard, either by publication of an identical text or by endorsement, at the latest by February1996, and conflicting national standards shall be withdrawn at the latest by February199
18、6. According to CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, UnitedKingdom. Content
19、s Page Foreword 2 0 Introduction 3 1 Scope and field of application 3 2 Reference 3 3 Principle 3 4 Reagents 3 5 Apparatus 3 6 Sampling 3 7 Preparation of calibration graph 3 8 Procedure 4 9 Expression of results 4 10 Test report 4ENISO787-19:1995 BSI 01-2000 3 0 Introduction This document is a part
20、 of ISO787, General methods of test for pigments. 1 Scope and field of application Part XIX of this International Standard specifies a general method of test for determining the water-soluble nitrates in a sample of pigment by a spectrophotometric method using salicylic acid. Part XIII specifies a m
21、ethod for determining the water-soluble nitrates in a sample of pigment using Nesslers method. NOTE 1When this general method is applicable to a given pigment, a cross-reference to it will be included in the International Standard relating to that pigment, with a note of any detailed modifications w
22、hich may be needed in view of the special properties of the pigment in question. Only when this general method is not applicable to a particular pigment will a special method for determination of nitrates be specified. NOTE 2It should be noted that the two methods may not necessarily give the same r
23、esult, and work is being carried out to compare the two methods. 2 Reference ISO842, Raw materials for paints and varnishes Sampling. 3 Principle The nitrate present in the extract of the pigment sample is used to nitrate salicylic acid in sulphuric acid medium. The nitro-compound formed is of an in
24、tense yellow colour in alkaline solution and the colour is measured spectrophotometrically at a wavelength of410nm. 4 Reagents All reagents shall be of recognized analytical reagent quality. Distilled water or water of equivalent purity shall be used. 4.1 Sulphuric acid, 1,84g/ml. 4.2 Sulphuric acid
25、,5N. 4.3 Ethanol, 95%(V/V). 4.4 Sodium salicylate, 5g/l solution, freshly prepared. 4.5 Sodium hydroxide, 300g/l solution. 4.6 Sodium hydroxide,4N solution. 4.7 Potassium nitrate, dried at120 C and cooled in a desiccator. 5 Apparatus 5.1 Spectrophotometer, suitable for measurements at a wavelength o
26、f410nm. 5.2 10mm cells for use with the spectrophotometer. 5.3 pH meter 5.4 One-mark volumetric flasks, of capacity50ml,100ml250ml and500ml, complying with ISO/R1042. 5.5 Pipettes, capacity10ml, complying with ISO/R648 and ISO/R835. 6 Sampling The sample of pigment used for the test shall be taken i
27、n accordance with the provisions of ISO842. 7 Preparation of calibration graph 7.1 Standard solution I Weigh163 0,1mg of the potassium nitrate(4.7), dissolve it in water in the100ml one-mark volumetric flask, make up to the mark and mix well. 7.2 Standard solution II Pipette10ml of standard solution
28、 I into a500ml one-mark volumetric flask, make up to the mark and mix well. 7.3 Construction of graph Pipette2,4,6,8 and10ml of standard solution II (corresponding to0,04,0,08,0,12,0,16 and0,2mg of NO 3respectively) into separate100ml beakers. To each beaker add1ml of sodium salicylate solution (4.4
29、), evaporate to dryness on a water-bath and allow to cool in a desiccator. Moisten each dried residue with1ml of the sulphuric acid(4.1) and allow to stand in the desiccator for10min. Afterwards, wash the contents into separate50ml one-mark volumetric flasks with water, add10ml of the sodium hydroxi
30、de solution(4.5) to each and cool to room temperature. Make up to the mark with water and mix well. Determine and record the absorbance of each of the solutions at410nm in10mm cells against a solution prepared in the same way as the previous solutions but omitting the nitrate solution. Construct a g
31、raph of absorbance against the mass ofNO 3 , in milligrams.ENISO787-19:1995 4 BSI 01-2000 8 Procedure 8.1 Pipette into a250ml one-mark volumetric flask50ml of the clear aqueous extract obtained, as appropriate for the pigment under test, by the hot extraction method 1) , or the cold extraction metho
32、d 2) . Make up to the mark with water and mix. NOTEIf the aqueous extract contains chromate, proceed as follows: Place50ml of the clear aqueous extract into a250ml glass beaker and add5ml of sulphuric acid(4.2) and2ml of ethanol(4.3). Heat the solution until any chromate present is reduced as indica
33、ted by the blue-green colour of the solution and the absence of aldehyde odour; take care to avoid losses by splashing. Cool and add sodium hydroxide solution(4.6) until just alkaline. Cool again and adjust the pH to8,0 0,5 measured by the pH meter. Filter through filter paper and wash with hot wate
34、r, collecting the filtrate and washings in a250ml one-mark volumetric flask. Cool, make up the mark and mix. 8.2 Pipette10ml of this solution to a100ml glass beaker. NOTEIf the nitrate content is found to be greater than0,1%, carry out a second determination, using5ml of solution. 8.3 Add to the bea
35、ker1ml of sodium salicylate solution (4.4) and proceed as specified in clause7, including the determination of the absorbance at410nm. 8.4 From the known absorbance of the test solution, determine from the calibration graph the corresponding mass of nitrate in milligrams. 9 Expression of results Cal
36、culate the water-soluble nitrate content expressed as NO 3 , as a percentage by mass, by the formula: where a is the mass, in milligrams, of NO 3corresponding to the absorbance of the test solution; m is the mass, in grams, of the pigment from which the clear aqueous extract was obtained. NOTEIf5ml
37、of the extract was taken because the nitrate content was greater than0,1%, the formula becomes. 10 Test report The test report shall include the following particulars: a) a reference to this International Standard or to a corresponding national standard; b) type and identification of the product und
38、er test; c) any deviation, agreed or otherwise, from the test procedure specified; d) the result of the test, and whether the hot or cold extraction method was used; e) date of the test. 1) SeePart III. 2) SeePart VIII. 25a 2m - 25a m -BSENISO787-19:1995 BSI 01-2000 List of references Seenational fo
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