1、BRITISH STANDARD BS 3900-B16: 1990 ISO 7252:1984 Methods of test for Paints Part B16: Determination of total mercury NOTEIt is recommended that this Part be read in conjunction with BS 3900-0, issued separately.BS3900-B16:1990 This British Standard, having been prepared under the directionof the Pig
2、ments, Paintsand Varnishes StandardsPolicy Committee, waspublished under the authorityof the Board of BSIandcomes into effect on 31 August 1990 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference PVC/l0 Draft for comment 82/54122 DC ISBN 0 580 18134 0 Co
3、mmittees responsible for this British Standard The preparation of this British Standard was entrusted by the Pigments, Paints and Varnishes Standards Policy Committee (PVC/-) to Technical Committee PVC/10, upon which the following bodies were represented: British Gas plc Chemical Industries Associat
4、ion Health and Safety Executive Institute of Metal Finishing Ministry of Defence Oil and Colour Chemists Association Paint Research Association Paintmakers Association of Great Britain Ltd. Titanium Pigment Manufacturers Technical Committee Amendments issued since publication Amd. No. Date CommentsB
5、S3900-B16:1990 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 References 1 3 Principle 1 4 Reagents and materials 1 5 Apparatus 1 6 Sampling 2 7 Procedure 2 8 Expression of results 4 9 Test report 4 Figure 1 Firing adap
6、ter 5 Figure 2 Typical apparatus for the determination of mercury byflamelessatomic absorption spectrometry 6 Figure 3 General view of combustion apparatus 7 Publication(s) referred to Inside back coverBS3900-B16:1990 ii BSI 10-1999 National foreword This Part of BS3900has been prepared under the di
7、rection of the Pigments, Paints and Varnishes Standards Policy Committee. It is identical with ISO7252:1984 “Paints and varnishes Determination of total mercury Flameless atomic absorption spectrometric method”, published by the International Organization for Standardization (ISO). CAUTION. The proc
8、edures described in this Part of BS3900are intended to be carried out by qualified chemists or by other suitably trained and/or supervised personnel. The substrates and procedures used in this method may be injurious to health if adequate precautions are not taken. Mercury, particularly in its vapou
9、r form, and its solutions are toxic. It is essential that breathing mercury and contact of mercury or its solutions with eyes and skin be avoided, and that all procedures be carried out in a well-ventilated fume-cupboard. This Part of BS3900refers only to its technical suitability and does not absol
10、ve the user from statutory obligations relating to health and safety. The Technical Committee has reviewed the provisions of ISO385-1:1984 1)and ISO648:1977, to which reference is made in5.14 and5.16 respectively, and has decided that they are acceptable for use in conjunction with this standard. IS
11、O385-1is related to BS846 “Specification for burettes” and ISO648is related to BS1583“Specification for one-mark pipettes”. Textual error. When adopting the text of the International Standard, the textual error given below was discovered. It has been marked in the text and has been reported to ISO i
12、n a proposal to amend the text of the International Standard. In note to5.1 insert “and this should be recorded in the test report” after “may be necessary”. This correction brings the text into line with that of BS3900-B12which describes a similar method. Cross-references International Standard Cor
13、responding British Standard ISO 1042:1981 BS 1792:1982 Specification for one-mark volumetric flasks (Identical) BS 3900 Methods of test for paints ISO 1512:1974 Part A1:1970 Sampling (Technically equivalent) ISO 1513:1980 Part A2:1983 Examination and preparation of samples for testing (Identical) IS
14、O 2629:1987 a BS 3978:1987 Specification for water for laboratory use (Identical) a Although ISO 3696:1987 and ISO 385-1:1984 are indicated in the text of ISO7252:1984 as being at the stage of draft, both are now published. 1) Although ISO3696:1987and ISO385-1:1984are indicated in the text of ISO725
15、2:1984as atbeing the stage of draft, both are now published.BS3900-B16:1990 BSI 10-1999 iii 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. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1to8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will b
17、e indicated in the amendment table on the inside front cover.iv blankBS3900-B16:1990 BSI 10-1999 1 1 Scope and field of application This International Standard describes a flameless atomic absorption spectrometric referee method for the determination of the total mercury content in paints and relate
18、d products. The method is applicable to products having total mercury contents in the range of about0,01to0,5% (m/m). NOTEThis method may also be applicable to products with a total mercury content of more than0,5% (m/m), provided that appropriate changes in reagent and test portion quantities are m
19、ade. 2 References ISO 385-1, Laboratory glassware Burettes Part1: General requirements 2) . ISO 648, Laboratory glassware One-mark pipettes. ISO 1042, Laboratory glassware One-mark volumetric flasks. ISO 1512, Paints and varnishes Sampling. ISO 1513, Paints and varnishes Examination and preparation
20、of samples for testing. ISO 3696, Water for laboratory use Specifications 3) . 3 Principle Combustion of the test portion with oxygen in an enclosed system. Reduction of the mercury(II) compounds contained in the resulting solution to elementary mercury. Entrainment of the mercury in a current of ga
21、s at ambient temperature and determination of the mercury, as the monoatomic vapour, by cold vapour (flameless) atomic absorption spectrometry at a wavelength in the region of253,7nm. 4 Reagents and materials During the analysis, use only reagents of recognized analytical grade and water of at least
22、 grade3purity according to ISO3696. 4.1 Oxygen, commercial grade, in a steel cylinder. 4.2 Tin(II) chloride dihydrate, 100g/l solution. Dissolve 25 g of tin(II) chloride dihydrate (SnCl 2 .2H 2 O) in50ml of35% (m/m) ( approximately1,18g/ml) hydrochloric acid and dilute to250ml with water. Add a few
23、granules of metallic tin and heat until any precipitate disappears. Ensure that a few granules of bright tin are present to stabilize the solution and, before use, that there is no precipitate. 4.3 Sulfuric acid, 5 % (m/m). 4.4 Nitric acid, approximately65% (m/m) ( approximately1,40g/ml). 4.5 Mercur
24、y, standard stock solution containing100mg of Hg per litre. Either a) transfer the contents of an ampoule of a standard mercury solution containing exactly0,1g of Hg into a1000ml one-mark volumetric flask, dilute to the mark with the sulfuric acid (4.3) and mix well; or b) weigh, to the nearest0,1mg
25、, 0,1354g of mercury(II) chloride, dissolve in the sulfuric acid(4.3) in a1000ml one-mark volumetric flask, dilute to the mark with the same sulfuric acid and mix well. 1 ml of this standard stock solution contains0,1mg of Hg. 4.6 Mercury, standard solution containing1mg ofHg per litre. Prepare this
26、 solution on the day of use. Pipette10ml of the standard stock solution (4.5) into a1000ml one-mark volumetric flask, dilute to the mark with the sulfuric acid (4.3) and mix well. 1 ml of this standard solution contains 14g of Hg. 5 Apparatus Ordinary laboratory apparatus and 5.1 Atomic absorption s
27、pectrometer, suitable for measurements at a wavelength of253,7nm and capable of operating with the measuring cell specified in5.2. NOTEIf special commercial mercury analysers using the cold vapour AAS principle are used (see note to7.1.2.1), appropriate amendment of the procedure described in7.1.2 a
28、nd7.2.3 may be necessary 4) . 2) At present at the stage of draft. (Partial revision of ISO/R385:1964.) 3) At present at the stage of draft. 4) See national foreword for details of textual errorBS3900-B16:1990 2 BSI 10-1999 5.2 Measuring cell, with windows (for example of quartz) transparent to ultr
29、aviolet radiation (in the region of253,7nm), the optical path length of which should be appropriate to the spectrometer being used, but not less than100mm. 5.3 Mercury hollow-cathode lamp or mercury discharge lamp 5.4 Potentiometric chart recorder NOTEA suitable peak measuring device such as an elec
30、tronic integrator may be used as an alternative. 5.5 Combustion flask or separating funnel, of capacity500ml, with a ground-glass joint. 5.6 Test portion holder (platinum gauze combustion basket) and firing adapter, suitable for fitting to the combustion flask (5.5) (see Figure 1). 5.7 Spark generat
31、or NOTEA high frequency vacuum tester has been found to be satisfactory. 5.8 Flowmeter, fitted with a stainless steel needle valve and capable of measuring flow rates within the range0,4to3l/min. 5.9 Pump, diaphragm type, capable of giving controlled air flow rates of0,4to3l/min, or cylinder of comp
32、ressed air or nitrogen equipped with a suitable pressure regulating valve. 5.10 Reaction vessel, comprising a test tube, of capacity25ml, with a ground glass joint neck to fit an interchangeable head and four-way stopcock (seeFigure 2). 5.11 Equipment, to prevent any condensation of water vapour in
33、the measuring cell. Any appropriate system may be used for this purpose (for example an infra-red lamp, a black electrical heating element, or a rod heater). 5.12 Flexible acid-resistant tubing, (for example silicon rubber tubing), suitable for connecting the apparatus (see Figure 2). 5.13 Capsules,
34、 of hardened gelatine, pharmaceutical grade. 5.14 Burettes, of capacity10ml and25ml, complying with the requirements of ISO385-1, 5.15 One-mark volumetric flasks, of capacity25ml and100ml, complying with the requirements of ISO1042. 5.16 Pipettes, of capacity1ml and5ml, complying with the requiremen
35、ts of ISO648. 5.17 Balance, capable of weighing to0,1mg. 6 Sampling Take a representative sample of the product to be tested as described in ISO1512. Examine and prepare the sample for testing as described in ISO1513. 7 Procedure 7.1 Preparation of the calibration graph 7.1.1 Preparation of the stan
36、dard matching solutions Prepare these solutions on the day of use. Into a series of six25ml one-mark volumetric flasks(5.15), introduce from the10ml burette(5.14), respectively, the volumes of the standard mercury solution (4.6) shown in the following table, dilute each to the mark with the sulfuric
37、 acid (4.3), and mix well. 7.1.2 Spectrometric measurement 7.1.2.1 Install the measuring cell (5.2) and the mercury spectral source (5.3) in the spectrometer(5.1) and optimize the conditions for the determination of mercury. Adjust the instrument in accordance with the manufacturers instructions and
38、 adjust the monochromator to the region of253,7nm in order to obtain the maximum absorbance. Connect the flowmeter (5.8), pump(5.9), reaction vessel (5.10), and measuring cell (5.2) with the minimum lengths of flexible tubing (5.12) as shown in Figure 2. NOTEA closed-circuit measuring system may be
39、used in which the mercury is recirculated by means of a pump. This will be particularly effective when the release of mercury vapour is delayed by interfering substances, e.g. bromide ions. 7.1.2.2 Switch on the pump and move the four-way stopcock to the by-pass position. Adjust the needle valve or
40、open the gas regulating valve to give a suitable flow rate (for example1l/min). Set the potentiometric chart recorder (5.4) to the appropriate range. Adjust the zero of the recorder to a suitable position on the chart and check for baseline drift and noise level (see7.1.2.4). Standard matching solut
41、ion No. Volume of the standard mercury solution (4.6) Corresponding concentration of Hg in the standard matching solution ml 4g/ml 0 a 1 2 3 4 5 0 1 2 3 4 5 0 0,04 0,08 0,12 0,16 0,20 a Blank matching solution.BS3900-B16:1990 BSI 10-1999 3 7.1.2.3 Disconnect the reaction vessel and, using a pipette
42、(5.16), place5ml of the standard matching solution No. 5into the vessel. Add by means of a pipette (5.16)1ml of the tin(II) chloride solution(4.2), mix well and immediately reconnect the reaction vessel. Reverse the four-way stopcock to allow the liberated mercury vapour to be swept through the meas
43、uring cell. 7.1.2.4 A peak will be indicated on the recorder chart and, by means of the potentiometer and flow range controls, adjust the height of the peak on the chart to about one-half the full-scale reading. Ensure that a sharp peak is obtained. Repeat if a further check of the adjustment is req
44、uired. Return the stopcock to the by-pass position and repeat the procedure using5ml aliquot portions of the remaining standard matching solutions. NOTEIt may be necessary to repeat the initial test several times using the standard matching solution No. 5in order to optimize the characteristics of t
45、he system. 7.1.3 Calibration graph Plot a graph having the masses, in micrograms, of Hg contained in1ml of the standard matching solutions as abscissae and the corresponding peak heights or, more precisely, the peak areas (for example, the products of the peak height and the peak width at half the p
46、eak height), reduced by the value for the blank matching solution, as ordinates. Over this range the curve should deviate only slightly from linearity. NOTEContamination of any portion of the apparatus with aromatic solvents may give false high results owing to absorption in the region of254nm. 7.2
47、Determination Carry out the determination in duplicate. 7.2.1 Test portion Place approximately20mg of the sample under test in a tared gelatine capsule (5.13) and close immediately. Weigh the capsule and test portion to the nearest0,1mg. 7.2.2 Combustion Place the weighed capsule in the test portion
48、 holder(5.6) (see Figure 1). Fill the combustion flask(5.5) with the oxygen (4.1) at atmospheric pressure, quickly introduce from a10ml burette(5.14) 3ml of the nitric acid (4.4) and insert the test portion holder making a gas tight seal at the ground glass joint. Attach the spark generator (5.7) to
49、 the electrical leads of the test portion holder (seeFigure 3), place the apparatus behind a safety screen and switch on the high voltage to activate the spark and ignite the test portion. After combustion is complete, shake the flask the and contents and allow to stand for30min with occasional shaking. Remove the test portion holder and add to the flask22ml of water from a25ml burette (5.14). Replace the test portion holder and shake thoroughly. Retain the bulk of the contents of the combustion flask in a stoppered glass container of capacity appr
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