1、BRITISH STANDARD BS3900-B4: 1986 ISO6503:1984 Total lead Methods of test for paints Part B4: Determination of total lead in paints and similar materials ISO title: Paints and varnishes Determination of total lead Flame atomic absorption spectrometric method It is recommended that this Part be read i
2、n conjunction with the general information in the Introduction to BS3900, issued separately. UDC667.612:543.06:546.815BS3900-B4:1986 This British Standard, having been prepared under the directionof the Pigments, Paints andVarnishes Standards Committee, was published underthe authority of the Board
3、ofBSI and comes intoeffect on 31January 1986 BSI 04-1999 First published July 1967 First revision January 1986 The committees responsible for this British Standard are shown inBS 3900: Introduction. The following BSI references relate to the work on this standard: Committee reference PVC/10 Draft fo
4、r comment79/55200DC ISBN 0580 14804 1 Amendments issued since publication Amd. No. Date of issue CommentsBS3900-B4:1986 BSI 04-1999 i Contents Page National foreword ii 1 Scope and field of application 1 2 References 1 3 Principle 1 4 Dry ashing method 1 5 Wet oxidation method 3 6 Determination 4 7
5、Expression of results 5 8 Test report 6 Table 1 3 Table 2 4 Table 3 5 Publications referred to Inside back coverBS3900-B4:1986 ii BSI 04-1999 National foreword This revision of this Part of BS3900 has been prepared under the direction of the Pigments, Paints and Varnishes Standards Committee. It is
6、identical with ISO6503:1984 “Paints and varnishes Determination of total lead Flame atomic absorption spectrometric method” published by the International Organization for Standardization (ISO). This Part of BS3900 supersedes BS3900-B4:1967, which is withdrawn. This revision of this Part of BS3900 h
7、as been prepared principally to replace method1 of the previous edition by a method using modern procedures, which are more rapid and have improved precision. Method2 of the1967 edition has not been included, although the Technical Committee is considering an alternative method to this which, if app
8、roved, will be introduced in due course. BS3900-B4 is not appropriate for determining the “soluble” lead content of paints. For this purpose, reference should be made to the method described in BS3900-B3 “Determination of “soluble” lead in the solid matter in liquid paints: method for use in conjunc
9、tion with The Control of Lead at Work Regulations,1980 (S.I. 1980 No.1248)”. It has been assumed in the drafting of this standard that it will be used and applied by those who are appropriately qualified and experienced. Terminology and conventions. The text of the international standard has been ap
10、proved 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 marker. In British Standards it is current
11、 practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard they should be read as “British Standard” and wherever the identification “ISO6503” appears, it should be read as “BS3900-B4”. In British Standards, it
12、is current practice to use the symbol “L” for litre (and its submultiples) rather than “I”, and to use the spelling “sulphur”, etc., instead of “sulfur”, etc. The Technical Committee has reviewed the provisions of ISO385/1 which has now been published as a partial revision of ISO/R385:1964, and has
13、decided that they are acceptable for use in conjunction with this standard. A related British Standard to ISO385/1:1984 is BS846:1985 “Specification for burettes”. Cross-references International standard Corresponding British Standard ISO1042:1983 BS1792:1982 Specification for one-mark volumetric fl
14、asks (Identical) BS3900 Methods of test for paints ISO1512:1974 Part A1:1970 Sampling (Technically equivalent) ISO1513:1980 Part A2:1983 Examination and preparation of samples for testing (Identical) ISO5725:1981 BS5497 Precision of test methods Part1:1979 Guide for the determination of repeatibilit
15、y and reproducibility for a standard test method (Technically equivalent)BS3900-B4:1986 BSI 04-1999 iii There are no British Standards corresponding to ISO3696, currently at draft stage, or ISO3856/1. The Technical Committee has reviewed the requirements for the water of grade3 purity, proposed for
16、inclusion in ISO3696. As these are compatible with the requirements of BS3978:1966 “Water for laboratory use”, the Technical Committee has decided that water complying with BS3978 is acceptable for use as required in4.2 and5.2. It is expected that ISO3856/1 which is only referred to in clause1 for i
17、nformation will be implemented in group B of BS3900. Additional information. With reference to4.5.1, the full procedure requires both the addition of liquid paraffin, as described in4.5.2 paragraph3, and the extraction described in4.5.4.2. The single test results referred to in7.2.1 and7.2.2 are mea
18、n values obtained in7.1 for the two test portions (see4.5.2 or5.5.1). 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 immu
19、nity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1 to6, 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 am
20、endment table on the inside front cover.iv blankBS3900-B4:1986 BSI 04-1999 1 1 Scope and field of application This International Standard describes a flame atomic absorption spectrometric method for the determination of total lead in paints and related products. The method is applicable to products
21、having totallead contents in the range of about0,01 to2%(m/m). NOTEThis method may also be applicable to products with a total lead content of more than2 %(m/m), but it should only be used when the precision does not exceed the appropriate values given in7.2. Two methods are given for the treatment
22、of the test portion; the dry ashing method (clause4) should be used as the referee method in cases of dispute. For the determination of lead in the test solution, the dithizone spectrophotometric method specified in ISO3856/1 may be used as an alternative method. 2 References ISO385/1, Laboratory gl
23、assware Burettes Part1: General requirements 1) . ISO1042, Laboratory glassware One-mark volumetric flasks. ISO1512, Paints and varnishes Sampling. ISO1513, Paints and varnishes Examination and preparation of samples for testing. ISO3696, Water for laboratory use Specifications 2) . ISO3856/1, Paint
24、s and varnishes Determination of “soluble” metal content Part1: Determination of lead content Flame atomic absorption spectrometric method and dithizone spectrophotometric method. ISO5725, Precision of test methods Determination of repeatability and reproducibility by inter-laboratory tests. 3 Princ
25、iple Decomposition of a test portion by either the dry ashing method (clause4) or the wet oxidation method (clause5), and determination of the lead by flame atomic absorption spectrometry. 4 Dry ashing method 4.1 Principle Evaporation of a test portion to dryness and ashing at475 C to remove all org
26、anic matter. Extraction of any lead in the residue with hydrochloric acid. 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 Sodium carbonate, anhydrous. 4.2.2 Magnesium carbonate. 4.2.3 Sulfur. 4.2
27、.4 Liquid paraffin. 4.2.5 Sodium sulfide, 10g/l solution. 4.2.6 Hydrochloric acid, approximately180g/l. Add450ml of concentrated hydrochloric acid36%(m/m), A approximately1,18g/ml to an approximately equal amount of water and dilute to1000ml. 4.2.7 Hydrochloric acid, approximately18g/l. Add100ml of
28、the hydrochloric acid(4.2.6) to water and dilute to1000ml. 4.2.8 Nitric acid, approximately315g/l. Add1 volume of concentrated nitric acid about65%(m/m), A approximately1,40g/ml to2volumes of water. 4.2.9 Lead, standard stock solution containing1g of Pb per litre. Either a) transfer the contents of
29、an ampoule of standard lead solution containing exactly1g of Pb into a1000ml one-mark volumetric flaskcontaining some water and30ml of the nitric acid(4.2.8), dilute to the mark with water and mix well; or b) weigh, to the nearest1mg,1,598g of lead nitrate Pb(NO 3 ) 2 (previously dried for2hat105 C)
30、, dissolve in water in a1000ml one-mark volumetric flask, add30ml of the nitricacid(4.2.8), dilute to the mark with water and mix well. 1ml of this standard stock solution contains1mg of Pb. 4.2.10 Lead, standard solution containing100mg of Pb per litre. Prepare this solution on the day of use. Pipe
31、tte10ml of the standard stock solution(4.2.9) into a100ml one-mark volumetric flask, dilute to the mark with the hydrochloric acid (4.2.7) and mix well. 1ml of this standard solution contains1004g of Pb. 1) At present at the stage of draft. (Partial revision of ISO/R385:1964.) 2) At present at the s
32、tage of draft.2 BSI 04-1999 BS3900-B4:1986 4.3 Apparatus Ordinary laboratory apparatus and 4.3.1 Crucibles, silica, preferably new. 4.3.2 Muffle furnace, capable of being maintained at475 25 C. 4.3.3 Hotplate, with energy regulation control. 4.4 Sampling Take a representative sample of the product t
33、o be tested by the method described in ISO1512. Examine and prepare the sample for testing as described in ISO1513. 4.5 Procedure 4.5.1 Preliminary tests If the composition of the product to be tested is not known, carry out qualitative tests for the presence of cellulose nitrate and antimony. If th
34、e results of these tests do not confirm the absence of cellulose nitrate and antimony, carry out the full procedure. 4.5.2 Test portion Carry out the procedure in duplicate. Mix the sample thoroughly and immediately transfer about5g into a weighed silica crucible(4.3.1). Weigh the test portion to th
35、e nearest10mg. If the product contains cellulose nitrate (see4.5.1), mix about2g of the liquid paraffin(4.2.4) with the test portion in the crucible. 4.5.3 Ashing Place the crucible and its contents on the hotplate(4.3.3) in a fume cupboard. Gradually increase the temperature of the hotplate to remo
36、ve all volatile solvents. Spread2g of the magnesium carbonate(4.2.2) over the contents of the crucible and, over a period of10min, progressively introduce the crucible into the muffle furnace(4.3.2) at approximately350C. Raise the temperature of the furnace to475 25C over a further period of60min an
37、d maintain at this temperature until ashing is complete. Ensure that an adequate supply of air for oxidation is available. Do not allow the material in the crucible to ignite at any stage. 4.5.4 Extraction 4.5.4.1 If the material does not contain antimony (see4.5.1), proceed as follows. Allow the cr
38、ucible and ash (see4.5.3) to cool. Transfer the crucible and ash to a250ml beaker, add100ml of the hydrochloric acid(4.2.6) and, using the hotplate(4.3.3), boil gently for15min. Then allow to digest for a further15min. While still hot, filter by decantation through a fine-texture filter paper 3) , i
39、nto a250ml beaker. Wash the paper and residue with hot water, collecting the washings in the beaker. Cool the beaker and transfer the filtrate and washings to a250ml one-mark volumetric flask. Dilute to the mark with water and mix well. 4.5.4.2 If the material contains antimony (see4.5.1), proceed a
40、s follows. Grind the ash (see4.5.3) to a fine powder, replace it in the same crucible and mix it with approximately10g of a mixture of equal parts of the sodium carbonate(4.2.1) and the sulfur(4.2.3). Cover the crucible and heat it over a moderate flame until there is no odour of sulfur dioxide; thi
41、s should take1 to2h. Cool the crucible and digest the contents with a small quantity of hot water until the melt is completely broken up. Filter, transferring all the residue to a filter paper with the sodium sulfide solution(4.2.5) and wash the residue with the sodium sulfide solution. Reject the f
42、iltrate. Transfer the filter paper and residue to a250ml beaker. Add15ml of the nitric acid(4.2.8) and, using the hotplate(4.3.3), boil gently for15min. Add100ml of the hydrochloric acid(4.2.6) and allow to digest for 30min. While still hot, filter through a fine-texture filter paper into a 250ml be
43、aker. Wash the paper and residue with hot water, collecting the washings in the beaker. Cool the beaker and transfer the filtrate and washings to a250ml one-mark volumetric flask. Dilute to the mark with water and mix well. 4.5.5 Preparation of test solutions From each extract solution(4.5.4) take a
44、n aliquot portion, of size determined by the expected lead content in the sample, in accordance with Table 1. 3) The following filter papers have been found to be suitable: Whatman Nos.42 and44 Schleicher and Schll Nos.589/3 and589/6.BS3900-B4:1986 BSI 04-1999 3 Table 1 NOTEIf the lead content is hi
45、gher than2%(m/m), a suitable aliquot portion should be taken. Place the aliquot portion in a100ml one-mark volumetric flask and, if a 5ml or10ml aliquot portion is taken, add10ml of the hydrochloricacid(4.2.6). Dilute to the mark with water and mix well. 4.5.6 Preparation of reagent blank Repeat the
46、 procedures described in4.5.3, 4.5.4.1 or4.5.4.2 and4.5.5, but omitting the test portion. 5 Wet oxidation method 5.1 Principle Wet oxidation of a test portion with a mixture of sulfuric acid and hydrogen peroxide in a beaker (method A) or with a mixture of sulfuric acid and nitric acid in a Kjeldahl
47、 flask (method B) to remove all organic matter. Heating to remove the excess sulfuric acid, and extraction of any lead (in the form of lead sulfate) in the residue with EDTA and ammonia solution. NOTEThe presence of antimony or cellulose nitrate in a sample does not cause interference with this meth
48、od. 5.2 Reagents During the analysis, use only reagents of recognized analytical grade and only water of at least grade3 purity according to ISO3696. 5.2.1 Sulfuric acid, about96%(m/m), A approximately1,84g/ml. 5.2.2 Hydrogen peroxide, approximately30%(m/m), or, with the appropriate additional safet
49、y precautions, approximately50%(m/m) solution. 5.2.3 Nitric acid, about65%(m/m), A approximately1,40g/ml. 5.2.4 Nitric acid, approximately315g/l. Add1 volume of the nitric acid(5.2.3) to2 volumes of water. 5.2.5 Ammonia solution, approximately85gNH3/l solution. Dilute380ml of concentrated ammonia solution25%(m/m) to1000ml with water. 5.2.6 EDTA (Ethylenediaminetetraacetic acid, disodium salt),37g/l solution. 5.2.7 Lead, standard stock solution containing1g of Pb per litre. Either a) tranfer the contents of an ampoule of standar
