1、BRITISH STANDARD BS 3900-B9: 1986 ISO 3856-4:1984 Methods of test for paints Part B9: Determination of “soluble” cadmium content ISO title: Paints and varnishes Determination of “soluble” metal content Part 4: Determination of cadmium content Flame atomic absorption spectrometric method and polarogr
2、aphic method It is recommended that this Part be read in conjunction with the general information in the Introduction to BS3900, issued separately. UDC 667.61:620.1BS3900-B9:1986 This British Standard, having been prepared under the directionof the Pigments, Paintsand Varnishes Standards Committee,
3、was published underthe authority of the Board ofBSI and comes into effect on 31January 1986 BSI 10-1999 The Committees responsible for thisBritish Standard are shown inBS3900: Introduction The following BSI references relate to the work on this standard: Committee reference PVC/10 Draft for comment
4、78/51515 DC ISBN 0 580 14948 X Amendments issued since publication Amd. No. Date of issue CommentsBS3900-B9:1986 BSI 10-1999 i Contents Page National foreword ii 0 Introduction 1 1 Scope and field of application 1 2 References 1 3 Flame atomic absorption spectrometric method 1 4 Polarographic method
5、 3 5 Test report 5 Publications referred to Inside back coverBS3900-B9:1986 ii BSI 10-1999 National foreword This Part of BS3900 has been prepared under the direction of the Pigments, Paints and Varnishes Standards Committee. It is identical with ISO3856-4:1984 “Paints and varnishes Determination of
6、 “soluble” metal content” Part4“Determination of cadmium content Flame atomic absorption spectrometric method and polarographic method” published by the International Organization for Standardization (ISO). It is assumed in the drafting of this standard that it will be used and applied by those who
7、are appropriately qualified and experienced. The procedures described in this standard are intended to be carried out by suitably trained and/or supervised personnel. The substances and procedures described may be injurious to health if inadequate precautions are taken. This standard refers only to
8、its technical suitability and does not absolve the user from statutory obligations relating to health and safety. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain co
9、nventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. 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 pr
10、actice 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 Standard” and “part of ISO3856” appear, referring to this standard, they should be read as “British Standard” and “Part of BS3900” respectively
11、 and wherever the identification “ISO3856-4” appears, it should be read as “BS3900-B9”. The Technical Committee has reviewed the provisions of ISO385-1:1984, and ISO648:1977 to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. I
12、SO385-1 is related to BS846 “Specification for burettes” and ISO648 is related to BS1583 “One-mark pipettes”. The Technical Committee has reviewed the proposed provisions of ISO3696 to which reference is made in3.2 and4.2 and has decided that they are acceptable for use in conjunction with this stan
13、dard. ISO3696 is 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 6713:1984 BS 3900 Methods of test for paints Part B5:1986 Preparation of aci
14、d extracts from liquid paints or coating powders (Identical)BS3900-B9:1986 BSI 10-1999 iii ISO 3856, to which reference is made in clause0, is published in a number of Parts of BS3900. At the time of publication of this standard, the relationship between other Parts of BS3900 and Parts of ISO3856 wa
15、s 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 of itself confer immunity from legal obligations. Part of ISO3856 Correspondi
16、ng Part of BS3900 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) ISO 3856-3:1984 Part B8:1986 Determination of “soluble” barium content (Identic
17、al) ISO 3856-5:1984 Part B10:1986 Determination of hexavalent chromium content of solid matter (Identical) ISO 3856-6:1984 Part B11:1986 Determination of total chromium content of liquid matter (Identical) ISO 3856-7:1984 Part B12:1986 Determination of “soluble” mercury content (Identical) a Attenti
18、on is drawn to a similar standard, BS3900-B3 “Determination of “soluble” lead in the solid matter 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 This document comprises a front cover, an inside front cover, pa
19、gesi to iv, pages1to6, 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 blankBS3900-B9:1986 BSI 10-1999 1 0 Introduction This International S
20、tandard is a part of ISO3856, Paints and varnishes Determination of “soluble” metal content. 1 Scope and field of application This part of ISO3856 describes two methods for the determination of the cadmium content of the test solutions prepared according to ISO6713 or other suitable International St
21、andards. The methods are applicable to paints having “soluble” cadmium contents in the range of about0,05 to 5% (m/m). The flame atomic absorption spectrometric method (AAS) (clause3) should be used as the referee method in cases of dispute. Other methods can be used by agreement between the interes
22、ted parties. A polarographic method is given in clause4. 2 References ISO 385-1, Laboratory glassware Burettes Part1: General requirements 1) . ISO 648, Laboratory glassware One-mark pipettes. ISO 1042, Laboratory glassware One-mark volumetric flasks. ISO 3696, Water for laboratory use Specification
23、s 2) . ISO 6713, Paints and varnishes Preparation of acid extracts from paints in liquid or powder form. 3 Flame atomic absorption spectrometric method 3.1 Principle Aspiration of the test solution into an acetylene/air flame. Measurement of the absorption of the selected spectral line emitted by a
24、cadmium hollow-cathode or cadmium discharge lamp, in the region of228,8nm. 3.2 Reagents and materials During the analysis, use only reagents of recognized analytical grade and only water of at least grade 3 purity according to ISO3696. 3.2.1 Hydrochloric acid, c(HCl)=0,07 mol/l. Use the hydrochloric
25、 acid, identical to that used for the preparation of the test solutions in accordance with ISO6713. (See3.4.2.) 3.2.2 Acetylene, commercial grade, in a steel cylinder. 3.2.3 Compressed air 3.2.4 Cadmium, standard stock solution containing1g of Cd per litre. Either a) transfer the contents of an ampo
26、ule of standard cadmium solution containing exactly1g of Cd into a 1000ml one-mark volumetric flask, dilute to the mark with the hydrochloric acid (3.2.1) and mix well; or b) weigh, to the nearest 1mg, a mass of a water-soluble cadmium salt of defined purity containing exactly 1g of Cd, dissolve in
27、the hydrochloric acid (3.2.1) in a 1000ml one-mark volumetric flask, dilute to the mark with the same hydrochloric acid and mix well; or c) weigh, to the nearest 1mg, exactly 1g of cadmium metal, dissolve it in the minimum of concentrated hydrochloric acid ( approximately1,18g/ml) in a 1000ml one-ma
28、rk volumetric flask, dilute to the mark with the hydrochloric acid (3.2.1) and mix well. 1ml of this standard stock solution contains 1mg of Cd. 3.2.5 Cadmium, standard solution containing 10mg of Cd per litre. Prepare this solution on the day of use. Pipette 10ml of the standard stock solution (3.2
29、4) into a 1000ml one-mark volumetric flask, dilute to the mark with the hydrochloric acid (3.2.1) and mix well. 1ml of this standard solution contains 104g of Cd. 3.3 Apparatus Ordinary laboratory apparatus and 3.3.1 Flame atomic absorption spectrometer, suitable for measurement at a wavelength of2
30、28,8nm and fitted with a burner fed with acetylene and air. 3.3.2 Cadmium hollow-cathode lamp or cadmium discharge lamp. 3.3.3 Burette, of capacity 10ml, complying with the requirements of ISO385-1. 3.3.4 One-mark volumetric flasks, of capacity100ml, complying with the requirements of ISO1042. 1) At
31、 present at the stage of draft. (Partial revision of ISO/R 385:1964.) 2) At present at the stage of draft.BS3900-B9:1986 2 BSI 10-1999 3.4 Procedure 3.4.1 Preparation of the calibration graph 3.4.1.1 Preparation of the standard matching solutions Prepare these solutions on the day of use. Into a ser
32、ies of five 100ml one-mark volumetric flasks (3.3.4), introduce from the burette (3.3.3), respectively, the volumes of the standard cadmium solution (3.2.5) shown in the following table, dilute each to the mark with the hydrochloric acid (3.2.1) and mix well. 3.4.1.2 Spectrometric measurements Insta
33、ll the cadmium spectral source (3.3.2) in the spectrometer (3.3.1) and optimize the conditions for the determination of cadmium. Adjust the instrument in accordance with the manufacturers instructions and adjust the monochromator to the region of 228,8nm in order to obtain the maximum absorbance. Ad
34、just the flow of the acetylene (3.2.2) and of the air(3.2.3) according to the characteristics of the aspirator-burner, and ignite the flame. Set the scale expansion, if fitted, so that the standard matching solution No. 4 (see table) gives almost a full-scale deflection. Aspirate into the flame each
35、 of the standard matching solutions (see3.4.1.1) in ascending order of concentration, and repeat with the standard matching solution No.3 to verify that the instrument has achieved stability. Aspirate water through the burner between each measurement, taking care to keep the rate of aspiration unifo
36、rm. 3.4.1.3 Calibration graph Plot a graph having the masses, in micrograms, of Cd contained in 1ml of the standard matching solutions as abscissae and the corresponding values of the absorbances, reduced by the reading for the blank matching solution, as ordinates. 3.4.2 Test solutions 3.4.2.1 Pigm
37、ent portion of the liquid paint and paint in powder form Use the solutions obtained by the procedure described in sub-clause8.2.3 of ISO6713. 3.4.2.2 Liquid portion of the paint Use the solutions obtained by the procedure described in sub-clause9.3 of ISO6713. 3.4.2.3 Other test solutions Use the te
38、st solutions obtained by other specified or agreed procedures. 3.4.3 Determination Measure first the absorbance of the hydrochloric acid (3.2.1) in the spectrometer (3.3.1) after having adjusted it as described in3.4.1.2. Then measure the absorbance of each test solution (3.4.2) three times and, aft
39、erwards, that of the hydrochloric acid again. Finally, re-determine the absorbance of standard matching solution No. 3 (see3.4.1.1) in order to verify that the response of the apparatus has not changed. If the absorbance of a test solution is higher than that of the standard matching solution with t
40、he highest cadmium concentration, dilute the test solution appropriately (dilution factorF) with a known volume of the hydrochloric acid(3.2.1). 3.5 Expression of results 3.5.1 Calculations 3.5.1.1 Pigment portion of the liquid paint Calculate the mass of “soluble” cadmium in the hydrochloric acid e
41、xtract, obtained by the method described in sub-clause8.2.3 of ISO6713, using the equation where Standard matching solution No. Volume of the standard cadmium solution (3.2.5) Corresponding concentration Cd in the standard matching solution ml 4g/ml 0 a 1 2 3 4 0 0,5 1 2 4 0 0,05 0,1 0,2 0,4 a Blank
42、 matching solution. a 0is the cadmium concentration, in micrograms per millilitre, of the blank test solution prepared by the method described in sub-clause8.4 of ISO6713; a 1is the cadmium concentration, in micrograms per millilitre, of the test solution obtained from the calibration graph; F 1is t
43、he dilution factor referred to in3.4.3; m 0is the mass, in grams, of “soluble” cadmium in the hydrochloric acid extract; V 1is the volume, in millilitres, of the hydrochloric acid plus ethanol used for the extraction described in sub-clause8.2.3 of ISO6713 (assumed to be 77ml).BS3900-B9:1986 BSI 10-
44、1999 3 Calculate the “soluble” cadmium content of the pigment portion of the paint using the equation where 3.5.1.2 Liquid portion of the paint Calculate the mass of cadmium in the solution (extract), obtained by the method described in sub-clause9.3 of ISO6713, using the equation where Calculate th
45、e cadmium content of the liquid portion of the paint, using the equation where 3.5.1.3 Liquid paint Calculate the total “soluble” cadmium content of the liquid paint as the sum of the results obtained according to3.5.1.1 and3.5.1.2, thus where is the total “soluble” cadmium content of the paint, exp
46、ressed as a percentage by mass. 3.5.1.4 Paint in powder form The total “soluble” cadmium content of the paint in powder form is obtained by appropriate modification of the calculations given in3.5.1.1. 3.5.1.5 Other test solutions If the test solutions were prepared by methods other than those given
47、 in ISO6713 (see3.4.2.3), it will be necessary to modify the equations for the calculation of cadmium content given in3.5.1.1 and3.5.1.2. 3.5.2 Precision No precision data are currently available. 4 Polarographic method 4.1 Principle Electrolysis of the test solution in a polarographic cell and meas
48、urement of the corresponding height of the potential step. 4.2 Reagents During the analysis, use only reagents of recognized analytical grade and only water of at least grade3 purity according to ISO3696. 4.2.1 Sulfuric acid, approximately 98% (m/m) ( approximately 1,84g/ml). 4.2.2 Hydrogen peroxide
49、 approximately30 % (m/m) solution. 4.2.3 Base solution Dissolve 27g of ammonium chloride and 0,05g of gelatine in water and add 32ml of ammonia solution approximately 33% (m/m) solution, approximately 0,880g/ml. Dilute the solution to500ml with water and mix well. 4.2.4 Nitrogen, commercial grade, in a steel cylinder. 4.2.5 Cadmium, standard stock solution containing1g of Cd per litre. Either a) transfer the contents of an ampoule of standard cadmium solution containing exactly1g of Cd into a 1000ml one-mark volumetric flask, dilute to the mark w
