1、BRITISH STANDARD BS 6200-3.16.2: 1986 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.16 Determination of lead Subsection 3.16.2 Steel: spectrophotometric method UDC 669.1:543.42.062:546.815BS6200-3.16.2:1986 This British Standard, having been prep
2、ared under the directionof the Iron and Steel Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 30 September 1986 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment 85/37324 DC ISB
3、N 0 580 15283 9 Amendments issued since publication Amd. No. Date of issue CommentsBS6200-3.16.2:1986 BSI 09-1999 i Contents Page Foreword ii 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Sampling 1 6 Procedure 1 7 Calculation and expression of results 2 8 Test report 3 Table 1 Precision data
4、 3 Publications referred to Inside back coverBS6200-3.16.2:1986 ii BSI 09-1999 Foreword This Subsection of BS 6200 has been prepared under the direction of the Iron and Steel Standards Committee. It supersedes method2 for the determination of lead in BSI Handbook No.19, to which it is technically eq
5、uivalent. BS 6200 is a multipart British Standard covering all aspects of the sampling and analysis of iron, steel and other ferrous metals. A list of contents, together with general information, will be given in Part1, to be published in due course. A British Standard does not purport to include al
6、l 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. Summary of pages This document comprises a front cover, an inside front cover, pagesi andi
7、i, pages1 to 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.BS6200-3.16.2:1986 BSI 09-1999 1 1 Scope This Subsection of BS 6200 describes a
8、 spectrophotometric method for the determination of lead in steel. The method is applicable to lead contents from0.05% m/m to0.5% m/m. NOTEThe titles of the publications referred to in this Subsection of BS6200 are listed on the inside back cover. 2 Principle Lead is converted to its dithizone compl
9、ex in ammoniacal citrate-cyanide solution and extracted into chloroform. The determination is completed spectrophotometrically. 3 Reagents During the analysis, use only reagents of recognized analytical reagent grade and only distilled water or water of equivalent purity. Use only reagents which are
10、 known to give a very low lead blank. 3.1 Ammonia solution, density ( ) 0.91 g/mL, diluted1 + 3. 3.2 Ammonia solution, 0.91g/mL, diluted 1 + 3. 3.3 Chloroform 3.4 Citric acid, 500 g/L solution. Dissolve 500 g of citric acid (H 8 C 6 O 7 .H 2 O) in water, dilute to1L and mix. 3.5 Dithizone, 0.05 g/L
11、solution. Dissolve 0.005 g of dithizone in chloroform, dilute to100mL with chloroform and mix. 3.6 Hydrochloric acid, 1.16g/mL to1.19g/mL. 3.7 Hydroxylammonium chloride, 100g/L solution. Dissolve 10g of hydroxylammonium chloride in water, dilute to100mL and mix. 3.8 Iron, of high purity, free from l
12、ead. 3.9 Lead, standard solution, corresponding to0.5mg lead per mL. Dissolve 0.500 g of high purity lead in20mL of nitric acid (3.11). Boil to remove nitrous fumes and cool. Transfer to a1L volumetric flask, dilute to the mark and mix. 3.10 Nitric acid, 1.42g/mL. 3.11 Nitric acid, 1.42g/mL, diluted
13、 1 +4. 3.12 Perchloric acid, 1.54g/mL. 3.13 Potassium cyanide, 100g/L solution. Dissolve 100g of potassium cyanide in water, dilute to1L and mix. 3.14 Potassium cyanide, 5 g/L solution. Dissolve 5 g of potassium cyanide in water, dilute to1L and mix. 3.15 Thymol blue, 0.4g/L solution. Dissolve 0.1 g
14、 of thymol blue by warming with4mL of sodium hydroxide solution (3.16) and5mL of ethanol. Add50mL of ethanol, dilute to250mL with water and mix. 3.16 Sodium hydroxide, 2 g/L. Dissolve 0.2 g of sodium hydroxide in water, dilute to100mL and mix. Prepare and store this solution in polyethylene containe
15、rs. 4 Apparatus Use ordinary laboratory apparatus. Use only volumetric glassware in accordance with class A of BS846, BS1583 or BS1792, as appropriate. Use also the following. 4.1 Spectrophotometer 4.2 Cells, having an optical path length of1cm. 5 Sampling Sampling shall be carried out in accordance
16、 with BS1837. NOTEBS 6200-2 “Methods of sampling and sample preparation”, which will supersede BS1837, is currently in preparation. On its publication, this Subsection will be amended to include a requirement to sample in accordance with BS6200-2. 6 Procedure 6.1 Test portion Weigh, to the nearest 0
17、.001g, a test portion of0.5g. 6.2 Blank test In parallel with the determination and following the same procedure, carry out a blank test using the same quantities of all reagents. NOTEA typical blank value for this method is equivalent to0.02% m/m lead. 6.3 Determination Place the test portion in a2
18、50mL conical beaker. Add10mL of hydrochloric acid (3.6), 1mL of nitric acid (3.10), and heat gently until solvent action ceases. Add 10 mL of perchloric acid (3.12), evaporate to fuming and continue fuming until any chromium present is fully oxidized. Add1mL of hydrochloric acid (3.6) dropwise, then
19、 reheat to fuming until any remaining chromium is again fully oxidized. If necessary, repeat the treatment with hydrochloric acid and fuming up to four times to remove residual chromium.BS6200-3.16.2:1986 2 BSI 09-1999 Cool, transfer to a250mL volumetric flask, dilute to the mark and mix. Transfer a
20、5mL aliquot to a125mL conical beaker. NOTEThis and all subsequent reagent additions should be made by means of a safety pipette or burette. Add 5 mL of hydroxylammonium chloride solution(3.7), stand the beaker in a boiling water bath for5min, then cool. Add 1 mL of citric acid solution (3.4) and a f
21、ew drops of thymol blue indicator (3.15). Then add ammonia solution (3.1) until the colour of the indicator changes to green-blue. Add a further5mL of ammonia solution (3.1) and cool. Transfer the solution to a100mL separating funnel marked at50mL and rinse with water. Add5mL of potassium cyanide so
22、lution (3.13) and dilute to the mark. From a burette, add 5.0mL of chloroform (3.3) and then add dithizone solution (3.5) from a burette,1.0mL at a time, shaking between each addition, until an excess of dithizone is indicated by the colour of the chloroform layer changing to purple-blue. Add2.0mL o
23、f dithizone solution (3.5) in excess, then sufficient chloroform (3.3) to bring the total amount of chloroform and dithizone solution to15.0mL. Shake vigorously for2min, allow the two layers to separate, then run the chloroform layer into another separating funnel containing40mL of potassium cyanide
24、 solution(3.14) and10mL of ammonia solution(3.2). Shake for1min and allow the layers to separate. Filter the chloroform layer through a5.5cm rapid filter paper into a dry1cm cell (4.2), discarding the initial few drops. Set the spectrophotometer (4.1) to zero absorbance in relation to water. Measure
25、 the absorbance of the test solution and blank solution at a wavelength of510nm. Convert the readings obtained to milligrams of lead by reference to the calibration graph (6.4). 6.4 Preparation of the calibration graph Place 0.50 g portions of high purity iron (3.8) intoaseries of six250mL conical f
26、lasks and add0.0, 1.0, 2.0, 3.0, 4.0 and5.0mL of leadstandard solution (3.9), corresponding to0,0.5,1.0, 1.5, 2.0 and2.5mg lead, respectively. Continue in accordance with6.3. Prepare a calibration graph by plotting the absorbance readings against the equivalent mass of lead. 7 Calculation and expres
27、sion of results 7.1 Calculation Calculate the lead content, expressed as a percentage by mass, from the equation where 7.2 Precision A planned trial of this method was carried out by five analysts, each from a different laboratory; six tests were carried out by each analyst on each of six samples. F
28、rom the results obtained, the95% confidence limits (2 s) have been calculated in accordance with BS5497-1 and are given inTable 1. The difference between two single results found on identical material by one analyst using the same apparatus within a short time interval will exceed the repeatability,
29、 r, not more than once in20cases in the normal and correct operation of the method. The difference between two single and independent results found by two operators working in different laboratories on identical test material will exceed the reproducibility, R, on average, not more than once in20 ca
30、ses in the normal and correct operation of the method. m 1 is the mass (in mg) of lead found in the test solution; m 0 is the mass (in mg) of lead found in the blank solution (6.2); m is the mass (in g) of the test portion (6.1). Load content m 1 m 0 10m - =BS6200-3.16.2:1986 BSI 09-1999 3 Table 1 P
31、recision data 8 Test report The test report shall contain the following information: a) identification of the sample; b) the method of analysis used, by reference to this Subsection of BS6200; c) the results obtained and the form in which they are expressed; d) any particular details noted during th
32、e determination; e) any operations not specified in this standard or any optional operations which may have influenced the results. Alloy type Lead content Repeatability , r Reproducibility, R % m/m Low carbon steel 0.05 0.0071 0.0085 1.5% m/m Cr, 0.2% m/m Mo, 1% m/m Al nitralloy 0.125 0.0097 0.0240
33、 Leaded low alloy steel 0.18 0.0102 0.0170 Leaded low alloy steel 0.20 0.0133 0.0198 Leaded plain carbon steel 0.22 0.0078 0.0120 Leaded plain carbon steel 0.28 0.0119 0.0156 NOTEThese values indicate the performance of the method on specially selected samples. This order of reproducibility may not
34、be achieved with commercial leaded steels as these are liable to major segregation of lead.4 blankBS6200-3.16.2:1986 BSI 09-1999 Publications referred to BS 846, Specification for burettes. BS 1583, Specification for one-mark pipettes. BS 1792, Specification for one-mark volumetric flasks. BS 1837,
35、Methods for the sampling of iron, steel, permanent magnet alloys and ferro-alloys. BS 5497, Precision of test methods. BS 5497-1, Guide for the determination of repeatability and reproducibility for a standard test method. BSI Handbook No. 19, Methods for the sampling and analysis of iron, steel and
36、 other ferrous metals 1) . 1) Referred to in the foreword only.BS 6200-3.16.2: 1986 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 Europe and at the inter
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