1、BRITISH STANDARD CONFIRMED AUGUST 1991 BS 3900-B6: 1986 ISO 3856-1:1984 Methods of test for paints Part B6: Determination of “soluble” lead content ISO title: Paints and varnishes Determination of “soluble” metal content Part 1: Determination of lead content Flame atomic absorption spectrometric met
2、hod and dithizone 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-B6:1986 This British Standard, having been prepared under the directionof the Pigments, Paintsand
3、 Varnishes StandardsCommittee, was published under the authority ofthe Board of BSI and comes intoeffect on 31 January 1986 BSI 10-1999 The Committees responsible for this British Standard are shown inBS3900: Introduction. The following BSI references relate to the work on this standard: Committee r
4、eference PVC/10 Draft for comment 78/51517 DC ISBN 0 580 14945 5 Amendments issued since publication Amd. No. Date of issue CommentsBS3900-B6:1986 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 spectrometr
5、ic method 1 4 Dithizone spectrophotometric method 3 5 Test report 6 Publications referred to Inside back coverBS3900-B6:1986 ii BSI 10-1999 National foreword This Part of BS 3900 1)has been prepared under the direction of the Pigments, Paints and Varnishes Standards Committee. It is identical with I
6、SO3856-1:1984 “Paints and varnishes Determination of “soluble” metal content” Part1“Determination of lead content Flame atomic absorption spectrometric method and dithizone spectrophotometric method” published by the International Organization for Standardization (ISO). It is assumed in the drafting
7、 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 personnel. The substances and procedures described may be injurious to health if
8、 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 the International Standard has been approved as suitable for publication as a Bri
9、tish 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 marker. In British Standards, it is current practice to use a full point on the basel
10、ine as the decimal marker. In British Standards it is current practice to use the symbol “L” for litre rather than “l”. 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, a
11、nd wherever the identification “ISO 3856-1” appears, it should be read as “BS3900-B6”. 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. ISO3
12、85-1 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 stand
13、ard. ISO3696 is related to BS3978 “Water for laboratory use”. 1) Attention 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)”. Cross-refe
14、rences International Standards Corresponding British Standards ISO 1042:1983 BS 1792:1982 Specification for one-mark volumetric flasks (Identical) ISO 4800:1977 BS 2021:1980 Specification for separating and dropping funnels for laboratory use (Identical) ISO 6713:1984 BS 3900 Methods of test for pai
15、nts Part B5:1986 Preparation of acid extracts from liquid paints or coating powders (Identical)BS3900-B6:1986 BSI 10-1999 iii ISO 3856, to which reference is made in clause 0, is published in a number of Parts of BS3900. At the time of publication of this standard, the relationship between other Par
16、ts of BS3900 and Parts of ISO3856 was 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 obli
17、gations. Part of ISO 3856 Corresponding Part of BS 3900 BS 3900 Methods of test for paints 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 (Identical) ISO 3856-4:1984 Part B9:1986 Determinatio
18、n of “soluble” cadmium content (Identical) 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
19、” mercury content (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1to 6, 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 a
20、mendment table on the inside front cover.iv blankBS3900-B6:1986 BSI 10-1999 1 0 Introduction This International Standard 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 determinat
21、ion of the lead content of the test solutions, prepared according to ISO6713 or other suitable International Standards. The methods are applicable to paints having “soluble” lead contents in the range of about0,05 to5% (m/m). The flame atomic absorption spectrometric (AAS) method (clause3) should be
22、 used as the referee method in cases of dispute. Other methods can be used by agreement between the interested parties. If a spectrophotometric method is agreed, the dithizone spectrophotometric method (clause4) should be used. 2 References ISO 385-1, Laboratory glassware Burettes Part1: General req
23、uirements 2) . ISO 648, Laboratory glassware One-mark pipettes. ISO 1042, Laboratory glassware One-mark volumetric flasks. ISO 3696, Water for laboratory use Specifications 3) . ISO 4800, Laboratory glassware Separating funnels and dropping funnels. ISO 6713, Paints and varnishes Preparation of acid
24、 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 lead hollow-cathode or lead discharge lamp, in the regio
25、n of283,3nm. 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 acid, identical to that used for the preparation of the tes
26、t 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 Lead, standard stock solution containing1g of Pb per litre. Either a) transfer the contents of an ampoule of standard lead solution containing exactly1g of Pb into a
27、1000 ml one-mark volumetric flask, dilute to the mark with the hydrochloric acid(3.2.1) and mix well; or b) weigh, to the nearest1mg,1,598g of lead nitrate Pb(NO 3 ) 2 (previously dried for2h at105 C), dissolve in the hydrochloric acid(3.2.1) in a1000ml one-mark volumetric flask, dilute to the mark
28、with the same hydrochloric acid and mix well. 1 ml of this standard stock solution contains 1 mg of Pb. 3.2.5 Lead, standard solution containing100mg of Pb per litre. Prepare this solution on the day of use. Pipette 100 ml of the standard stock solution (3.2.4) into a1000ml one-mark volumetric flask
29、, dilute to the mark with the hydrochloric acid (3.2.1) and mix well. 1 ml of this standard solution contains1004g of Pb. 3.3 Apparatus Ordinary laboratory apparatus and 3.3.1 Flame atomic absorption spectrometer, suitable for measurements at a wavelength of283,3nm and fitted with a burner fed with
30、acetylene and air. 3.3.2 Lead hollow-cathode lamp or lead discharge lamp 3.3.3 Burette, of capacity50ml, complying with the requirements of ISO385-1. 3.3.4 One-mark volumetric flasks, of capacity100ml, complying with the requirements of ISO1042. 2) At present at the stage of draft. (Partial revision
31、 of ISO/R 385:1964.) 3) At present at the stage of draft.BS3900-B6:1986 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 series of six100ml one-mark volumetric flasks (3.3.4
32、), introduce from the burette (3.3.3), respectively, the volumes of the standard lead 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 Install the lead spectral source (3.3.2) in the spectromete
33、r (3.3.1) and optimize the conditions for the determination of lead. Adjust the instrument in accordance with the manufacturers instructions and adjust the monochromator to the region of283,3nm in order to obtain the maximum absorbance. Adjust the flow of the acetylene (3.2.2) and of the air(3.2.3)
34、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.5 (see table) gives almost a full-scale deflection. Aspirate into the flame each of the standard matching solutions (see3.4.1.1) in ascending
35、order of concentration, and repeat with the standard matching solution No.4 to verify that the instrument has achieved stability. Aspirate water through the burner between each measurement, taking care to keep the rate of aspiration uniform. 3.4.1.3 Calibration graph Plot a graph having the masses,
36、in micrograms, of Pb contained in1ml 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 Pigment portion of the liquid paint and paint in powder form Use th
37、e solutions obtained by the procedure described in sub-clause8.2.3 or 8.3.2 of ISO6713, as appropriate. 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 solutions obtained by other specified or
38、 agreed procedures (for example, by the procedure described in sub-clause8.3.1.4 of ISO6713). 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 in 3.4.1.2. Then measure the absorbance of each test solut
39、ion (3.4.2) three times and, afterwards, that of the hydrochloric acid again. Finally, re-determine the absorbance of standard matching solution No.4 (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 st
40、andard matching solution with the highest lead concentration, dilute the test solution appropriately (dilution factor F) 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” lead
41、in the hydrochloric acid extract obtained by the method described in sub-clause8.2.3 or8.3.2 of ISO6713, using the equation where Standard matching solution No. Volume of the standard lead solution (3.2.5) Corresponding concentration of Pb in the standard matching solution ml 4g/ml 0 a 1 2 3 4 5 0 2
42、,5 5 10 20 30 0 2,5 5 10 20 30 a Blank matching solution. a 0 is the lead concentration, in micrograms per millilitre, of the blank test solution prepared by the method described in sub-clause8.4 of ISO6713; a 1 is the lead concentration, in micrograms per millilitre, of the test solution obtained f
43、rom the calibration graph; F 1 is the dilution factor referred to in3.4.3; m 0 is the mass, in grams, of “soluble” lead in the hydrochloric acid extract;BS3900-B6:1986 BSI 10-1999 3 Calculate the “soluble” lead content of the pigment portion of the paint using the equation where 3.5.1.2 Liquid porti
44、on of the paint Calculate the mass of lead in the solution (extract), obtained by the method described in sub-clause9.3 of ISO6713, using the equation where Calculate the lead content of the liquid portion of the paint, using the equation where 3.5.1.3 Liquid paint Calculate the total “soluble” lead
45、 content of the liquid paint as the sum of the results obtained according to3.5.1.1 and 3.5.1.2, thus where is the total “soluble” lead content of the paint, expressed as a percentage by mass. 3.5.1.4 Paint in powder form The total “soluble” lead content of the paint in powder form is obtained by ap
46、propriate 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 in ISO6713 (see3.4.2.3), it will be necessary to modify the equations for the calculation of lead content given in3.5.1.1 and3.5.1.2. 3.5.2 P
47、recision No precision data are currently available. 4 Dithizone spectrophotometric method 4.1 Principle Extraction of the lead from the test solution with a solution of dithizone in 1,1,1-trichloroethane. Spectrophotometric measurement of the red colour of the lead dithizonate at a wavelength of abo
48、ut520nm. 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 Hydrochloric acid, c(HCl) = 0,07 mol/l. Use the hydrochloric acid, identical to that used for the preparation of the test solutions in acco
49、rdance with ISO6713. (See4.4.2.) V 1 is the volume, in millilitres, of the hydrochloric acid plus ethanol used for the extraction described in sub-clause8.2.3 or 8.3.2.4 of ISO6713 (assumed to be77ml or502ml respectively). is the “soluble” lead content, of the pigment portion of the paint, expressed as a percentage by mass of the paint; m 1 is the mass, in grams, of the test portion taken to prepare the solution described in sub-clause8.2.3 or8.3.2.4 of ISO6713; P is the pigment content of the liquid paint, expressed as a percentage by mass, obtai
