BS 3900-B10-1986 Methods of test for paints - Tests involving chemical examination of liquid paints and dried paint films - Determination of hexavalent chromium content of solid ma.pdf

1、BRITISH STANDARD BS 3900-B10: 1986 ISO 3856-5: 1984 Methods of Test for paints Part B10: Determination of hexavalent chromium content of solid matter ISO title: Paints and varnishes Determination of “soluble” metal content Part 5: Determination of hexavalent chromium content of the pigment portion o

2、f the liquid paint or the paint in powder form Diphenylcarbazide spectrophotometric method It is recommended that this Part be read in conjunction with the general information in the Introduction to BS 3900, issued separately. UDC 667.61:620.1BS3900-B10:1986 This British Standard, having been prepar

3、ed under the directionof the Pigments, Paintsand Varnishes StandardsCommittee, was published underthe authority ofthe Board ofBSI and comesintoeffect on 31January1986 BSI 04-2000 The Committees responsible for this British Standard are shown inBS 3900: Introduction. The following BSI references rela

4、te to the work on this standard: Committee reference PVC/10 Draft for comment 78/51516 DC ISBN 0 580 14949 8 Amendments issued since publication Amd. No. Date of issue CommentsBS3900-B10:1986 BSI 04-2000 i Contents Page National foreword ii 0 Introduction 1 1 Scope and field of application 1 2 Refer

5、ences 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Procedure 2 7 Expression of results 2 8 Test report 3 Publications referred to Inside back coverBS3900-B10:1986 ii BSI 04-2000 National foreword This Part of BS3900has been prepared under the direction of the Pigments, Paints and Varnishes Standards

6、 Committee. It is identical with ISO3856-5:1984“Paints and varnishes Determination of “soluble” metal content” Part 5 “Determination of hexavalent chromium content of the pigment portion of the liquid paint or the paint in powder form Diphenylcarbazide spectrophotometric method” published by the Int

7、ernational Organization for Standardization (ISO). It is assumed in the drafting of this standard that it will be used and applied by those who are appropriately qualified and experienced. The procedures described in this standard are intended to be carried out by suitably trained and/or supervised

8、personnel. The substances and procedures described may be injurious to health if inadequate precautions are taken. This standard refers only to its technical suitability and does not absolve the user from statutory obligations relating to health and safety. Terminology and conventions. The text of t

9、he International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marke

10、r. In British Standards, it is current practice to use a full point on the baseline as the decimal marker. In British Standards it is current practice to use the symbol “L” for litre rather than “l”, and to use the spelling “sulphur”, etc., instead of “sulfur”, etc. Wherever the words “International

11、 Standard” and “part of ISO 3856” appear, referring to this standard, they should be read as “British Standard” and “Part of BS 3900” respectively, and wherever the identification “ISO 3856-5” appears, it should be read as “BS 3900-B10”. The Technical Committee has reviewed the provisions of ISO 385

12、-1:1984, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. ISO385-1is related to BS846“Specification for burettes”. The Technical Committee has reviewed the proposed provisions of ISO3696to which reference is made in clause 4

13、and has decided that they are acceptable for use in conjunction with this standard. ISO3696is related to BS3978“Water for laboratory use”. Cross-references International Standards Corresponding British Standards ISO 1042:1983 BS 1792:1982 Specification for one-mark volumetric flasks (Identical) ISO

14、6713:1984 BS 3900 Methods of test for paints Part B5:1986 Preparation of acid extracts from liquid paints or coating powders (Identical)BS3900-B10:1986 BSI 04-2000 iii ISO 3856, to which reference is made in clause 0, is published in a number of Parts of BS 3900. At the time of publication of this s

15、tandard, the relationship between other Parts of BS3900and Parts of ISO3856was as follows: 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

16、of itself confer immunity from legal obligations. Part of ISO 3856 Corresponding Part of BS 3900 BS 3900 Methods of test for paints ISO 3856-1:1984 a Part B6:1986 Determination of “soluble” lead content (Identical) ISO 3856-2:1984 Part B7:1986 Determination of “soluble” antimony content (Identical)

17、ISO 3856-3:1984 Part B8:1986 Determination of “soluble” barium content (Identical) ISO 3856-4:1984 Part B9:1986 Determination of “soluble” cadmium content (Identical) ISO 3856-6:1984 Part B11:1986 Determination of total chromium content of liquid matter (Identical) ISO 3856-7:1984 Part B12:1986 Dete

18、rmination of “soluble” mercury content (Identical) a Attention is drawn to a similar standard, BS 3900-B3 “Determination of “soluble” lead in the solidmatter in liquid paints: method for use in conjunction with The Control of Lead at Work Regulations, 1980 (S.I. 1980 No. 1248)”. Summary of pages Thi

19、s document comprises a front cover, an inside front cover, pages i to iv, pages1to 4, 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.iv blankB

20、S3900-B10:1986 BSI 04-2000 1 0 Introduction This International Standard is a part of ISO 3856, Paints and varnishes Determination of “soluble” metal content. 1 Scope and field of application This part of ISO3856describes a diphenylcarbazide spectrophotometric method for the determination of the “sol

21、uble” hexavalent chromium content of the hydrochloric acid extract of the pigment portion of the liquid paint or of the paint in powder form, prepared in accordance with sub-clause 8.2.3 of ISO6713or other suitable International Standards. The method is applicable to paints having hexavalent chromiu

22、m contents in the range of about0,05to5% (m/m). Other methods can be used by agreement between the interested parties, provided that the methods are specific for hexavalent chromium but this spectrophotometric method is the referee method in cases of dispute. 2 References ISO 385-1, Laboratory glass

23、ware Burettes Part1: General requirements 1) . ISO 1042, Laboratory glassware One-mark volumetric flasks. ISO 3696, Water for laboratory use Specifications 2) . ISO 6713, Paints and varnishes Preparation of acid extracts from paints in liquid or powder form. 3 Principle Formation of a coloured compl

24、ex from hexavalent chromium and diphenylcarbazide solution. After addition of orthophosphoric acid and sulfuric acid, spectrophotometric measurement of the colour at a wavelength in the region of540nm. 4 Reagents During the analysis, use only reagents of recognized analytical grade and only water of

25、 at least grade3purity according to ISO 3696. 4.1 Diphenylcarbazide, solution. Dissolve0,25g diphenylcarbazide in a mixture of50ml of acetone and50ml of water. 4.2 Sodium hydroxide, c(NaOH) = 2 mol/l solution. 4.3 Sulfuric acid, c(H 2 SO 4 ) = 1 mol/l. 4.4 Orthophosphoric acid, approximately85% (m/m

26、) ( approximately1,69g/ml). 4.5 Hydrochloric acid, c(HCl) = 0,07 mol/l. Use the hydrochloric acid, identical to that used for the preparation of the test solutions in accordance with ISO 6713. (See 6.2.) 4.6 Hexavalent chromium, standard stock solution containing100mg of Cr(VI) per litre. Weigh, to

27、the nearest0,1mg,282,9mg of drypotassium dichromate, dissolve in water in a1000 ml one-mark volumetric flask, dilute to the mark with water and mix well. 1 ml of this standard stock solution contains1004g of Cr(VI). 4.7 Hexavalent chromium, standard solution containing1mg of Cr(VI) per litre. Prepar

28、e this solution on the day of use. Pipette10ml of the standard stock solution (4.6) into a1000 ml one-mark volumetric flask, dilute to the mark with the hydrochloric acid (4.5) and mix well. 1 ml of this standard solution contains14g of Cr(VI). 5 Apparatus Ordinary laboratory apparatus and 5.1 Spect

29、rophotometer, suitable for measurements at a wavelength of about540nm, fitted with cells of optical path length10or20mm. 5.2 pH-meter, with glass electrode and reference electrode. 5.3 Burette, of capacity50ml, complying with the requirements of ISO 385-1. 5.4 One-mark volumetric flasks, of capacity

30、50ml, complying with the requirements of ISO 1042. 1) At present at the stage of draft. (Partial revision of ISO/R 385-1964.) 2) At present at the stage of draft.BS3900-B10:1986 2 BSI 04-2000 6 Procedure 6.1 Preparation of the calibration graph 6.1.1 Preparation of standard colorimetric solutions Pr

31、epare these solutions on the day of use. Into a series of five50ml beakers, introduce from the burette (5.3), respectively, the volumes of the standard hexavalent chromium solution (4.7) shown in the following table. Treat the contents of each beaker as follows: Add5ml of the sodium hydroxide soluti

32、on (4.2). Using the pH-meter (5.2), adjust the pH value of thesolution to7,0by the addition of the sulfuric acid (4.3). Add2ml of the diphenylcarbazide solution (4.1) and1to2ml of the orthophosphoric acid (4.4), together with5ml of the sulfuric acid(4.3). Transfer to a50ml one-mark volumetric flask

33、(5.4), dilute to the mark with water and mix well. 6.1.2 Spectrophotometric measurements Immediately measure the absorbances of the standard colorimetric solutions (6.1.1) with the spectrophotometer (5.1) at the wavelength of maximum absorption (about540nm) against water in the reference cell. Befor

34、e each measurement, rinse the cell with the standard colorimetric solution. Deduct the absorbance of the compensation solution from those of the other standard colorimetric solutions. 6.1.3 Calibration graph Plot a graph having the masses, in micrograms, of Cr(VI) contained in1ml of the standard col

35、orimetric solutions as abscissae and the corresponding values of absorbance as ordinates. If the procedure has been carried out correctly, the calibration graph should be a straight line. 6.2 Test solutions Use the solutions obtained by the procedure described in sub-clause 8.2.3 of ISO6713or other

36、specified or agreed procedures. 6.3 Determination Introduce from the burette (5.3), into a50ml beaker, a volume of each of the test solutions (6.2) such that its absorbance lies on the calibration graph. Treat the solution as described in 6.1.1. Measure the absorbance as described in 6.1.2. 7 Expres

37、sion of results 7.1 Calculations Calculate the mass of “soluble” hexavalent chromium in the hydrochloric acid extract obtained by the method described in sub-clause 8.2.3 of ISO6713, using the equation where a 0 is the hexavalent chromium concentration, in micrograms per millilitre, of the blank tes

38、t solution prepared by the method described in sub-clause 8.4 of ISO 6713; a 1 is the hexavalent chromium concentration, in micrograms per millilitre, of the test solution obtained from the calibration graph; m 0 is the mass, in grams, of “soluble” hexavalent chromium in the hydrochloric acid extrac

39、t; V 1 is the volume, in millilitres, of the hydrochloric acid plus ethanol taken for the extraction described in sub-clause 8.2.3 of ISO6713(assumed to be77ml); V 3 is the volume, in millilitres, of the aliquot portion of the hydrochloric acid plus ethanol taken for the test. Calculate the “soluble

40、” hexavalent chromium content of the pigment portion of the paint using the equation where is the “soluble” hexavalent chromium content of the pigment portion of the paint, expressed as a percentage by mass of the paint; Standard colorimetric solution No. Volume of the standard hexavalent chromium s

41、olution (4.7) Corresponding concentration of Cr(VI) in the standard colorimetric solution ml 4g/ml 0 a 0 0 1 5 0,1 2 10 0,2 3 15 0,3 4 20 0,4 a Compensation solution. c Cr 1BS3900-B10:1986 BSI 04-2000 3 m 1 is the mass, in grams, of the test portion taken to prepare the solution described in sub-cla

42、use 8.2.3 of ISO 6713; P is the pigment content of the liquid paint, expressed as a percentage by mass, obtained by the appropriate method described in clause 6 of ISO 6713. NOTE 1The total “soluble” chromium content of the liquid paint, consisting of the “soluble” hexavalent chromium content of the

43、 pigment portion plus the total chromium content of the liquid portion of the paint and expressed as a percentage by mass of the paint, is given by the sum of the results obtained according to ISO3856-6and this part of ISO 3856. NOTE 2The total “soluble” hexavalent chromium content of the paint in p

44、owder form is obtained by appropriate modification of the calculations given in 7.1. If the test solutions were prepared by methods other than that given in ISO6713(see 6.2), it will be necessary to modify the equations for the calculation of hexavalent chromium content given above. 7.2 Precision No

45、 precision data are currently available. 8 Test report The test report shall contain at least the following information: a) the type and identification of the product tested; b) a reference to this International Standard (ISO3856-5); c) the method for the separation of the solid portion of the produ

46、ct under test according to ISO6713,clause 6 (method A, B or C), where appropriate 3) ; d) the solvent or the solvent mixture used for the extraction, where appropriate 3) ; e) the results of the test, expressed as a percentage by mass of the product: either the “soluble” hexavalent chromium content

47、in the pigment portion of the paint, or the total “soluble” hexavalent chromium content of the paint in powder form; f) any deviation, by agreement or otherwise, from the test procedure specified; g) the date of the test. 3) Not required for paints in powder form (see clause 7 of ISO 6713).4 blankBS

48、3900-B10:1986 BSI 04-2000 Publications referred to See national foreword.BS 3900-B10: 1986 ISO 3856-5: 1984 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in

49、 Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards 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 BritishStandard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel