1、BRITISH STANDARD BS 6075-11: 1981 ISO 5993:1979 Methods of Sampling and test for sodium hydroxide for industrial use Part 11: Determination of mercury content (flameless atomic absorption method) ISO title: Sodium hydroxide for industrial use Determination of mercury content Flameless atomic absorpt
2、ion spectrometric method NOTEIt is recommended that this Part be read in conjunction with the information in the “Generalintroduction” published separately as BS 6075-0. UDC 661.322.1:546.33 36:543.422.062:546.49BS6075-11:1981 This British Standard, having been prepared under the directionof the Che
3、micals Standards Committee, was published under the authority ofthe Executive Board and comesinto effect on 27February1981 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference CIC/22 Draft for comment 77/54039 DC ISBN 0 580 12061 9 Amendments issued since
4、 publication Amd. No. Date of issue CommentsBS6075-11:1981 BSI 10-1999 i Contents Page National foreword ii 1 Scope and field of application 1 2 References 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling 2 7 Procedure 2 8 Expression of results 4 9 Notes on procedure 4 10 Test report 4 11 Bibli
5、ography 5 Annex ISO publications relating to sodium hydroxide for industrial use 6 National appendix Removal of mercury from waste solutions 7 Figure Typical apparatus for determination of mercury by atomic absorption 5 Publications referred to Inside back coverBS6075-11:1981 ii BSI 10-1999 National
6、 foreword This Part of BS 6075 is identical with ISO 5993 “Sodium hydroxide for industrial use Determination of mercury content Flameless atomic absorption spectrometric method”, published in 1979 by the International Organization for Standardization (ISO). The National appendix to this Part of this
7、 standard describes a procedure to remove mercury from waste solutions from the analytical procedures described herein. This procedure is technically equivalent to that described in ISO 5790 “Inorganic chemical products for industrial use General method for determination of chloride content Mercurim
8、etric method” (which has not been implemented as a British Standard). 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 conventions are not identical with those used
9、in British Standards; attention is especially drawn to the following. The comma has been used throughout as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this s
10、tandard, they should be read as “British Standard”. There is no British Standard equivalent to ISO 5790. However, the National appendix of this Part of BS 6075 is technically equivalent to Annex B of ISO 5790 which is the subject of the reference in the note to 4.8. The standards listed in the Annex
11、 are intended for information only. Corresponding British Standards are listed in BS 6075-0. Additional information Water. Water complying with the requirements of clause 4 is specified in BS 3978 “Water for laboratory use”. Hydrochloric acid, approximately 1.18 g/ml, about 36 % (m/m) solution, whic
12、h is the corresponding reagent normally obtainable in the UK, is suitable for use in place of the solution specified in 4.7. WARNINGS Hydroxylammonium chloride, specified in 4.4, is corrosive and irritant. Avoid contact with skin and eyes. Iodine, specified in 4.6, is toxic and corrosive. Avoid brea
13、thing vapour. Avoid contact with skin and eyes. Mercury (II) chloride, specified in 4.7, is toxic (with danger of cumulative effects) and is irritant, particularly in the form of dust. Avoid breathing dust. Avoid contact with skin and eyes. Cross-references International Standard Corresponding Briti
14、sh Standard BS 6075 Methods of sampling and test for sodium hydroxide for industrial use ISO 3195:1975 Part 5:1981 Sampling and preparation of main test solution (Identical) ISO 5992:1979 Part 10:1981 Determination of mercury content (photometric method) (Identical)BS6075-11:1981 BSI 10-1999 iii A B
15、ritish 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. Summary of pages This document comprises a f
16、ront cover, an inside front cover, pages i to iv, pages1to 8, 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 blankBS6075-11:1981 BSI 10-199
17、9 1 1 Scope and field of application This International Standard specifies a flameless atomic absorption spectrometric method for the determination of the mercury content of sodium hydroxide for industrial use. The method is applicable to liquid or solid productshaving mercury (Hg) contents greater
18、than 0,02 mg/kg. NOTEThe alternative dithizone photometric method for the determination of mercury content, specified in ISO 5992, is intended for use in laboratories where flameless atomic absorption equipment is not available. 2 References ISO 3195, Sodium hydroxide for industrial use Sampling Tes
19、t sample Preparation of the main solution for carrying out certain determinations. ISO 5790, Inorganic chemical products for industrial use General method for determination of chloride content Mercurimetric method. ISO 5992, Sodium hydroxide for industrial use Determination of mercury content Dithiz
20、one photometric method. 3 Principle Oxidation of the mercury contained in a test portion to mercury(II) ions by potassium permanganate in the presence of sulphuric acid. Reduction of the excess oxidant by hydroxylammonium chloride. Reduction of the mercury(II) ions to mercury by tin(II) chloride. En
21、trainment of the mercury in air or nitrogen and passage of the gaseous mixture through a measuring cell. Measurement of the absorption at a wavelength of253,7 nm, using an atomic absorption spectrometer. 4 Reagents During the analysis, use only reagents of recognized analytical grade having the lowe
22、st possible mercury content, and only distilled water or water of equivalent purity. 4.1 Nitrogen, in a cylinder. 4.2 Sulphuric acid, approximately 490 g/l solution. 4.3 Potassium permanganate, 40 g/l solution. 4.4 Hydroxylammonium chloride (NH 2 OH.HCl), 100 g/l solution. 4.5 Tin(II) chloride, 100
23、g/l solution in hydrochloric acid. Dissolve 25 g of tin(II) chloride dihydrate (SnCl 2 .2H 2 O) in 50 ml of hot hydrochloric acid solution, approximately 1,19 g/ml. Transfer the solution quantitatively to a 250 ml one-mark volumetric flask, dilute to the mark with water and mix. Transfer this soluti
24、on to a glass flask and purge it by bubbling the nitrogen (4.1) through for5min, then add a few particles of granular metallic tin to assist stabilization. Discard when turbidity appears. 4.6 Iodine, 2,5 g/l solution. Dissolve 2,5 g of iodine and 30 g of potassium iodide in water, dilute to the mark
25、 in a 1 000 ml one-mark volumetric flask and mix. 4.7 Mercury, standard solution corresponding to1,000 g of Hg per litre. Dissolve 1,354 g of mercury(II) chloride (HgCl 2 ) in25 ml of hydrochloric acid, approximately 1,19 g/ml 38 % (m/m) solution. Transfer the solution quantitatively to a 1 000 ml o
26、ne-mark volumetric flask, dilute to the mark with water and mix. Store this solution in a cool, dark place and renew after 2 months. 1 ml of this standard solution contains 1 mg of Hg. 4.8 Mercury, standard solutions corresponding to1and 0,1 mg of Hg per litre. Prepare these solutions on the day of
27、use by successive dilution of the standard solution (4.7) with an approximately 11 g/l hydrochloric acid solution. These solutions should be freshly prepared as their concentration can vary because of loss of mercury through evaporation or adsorption by the flask. 1 ml of each of these standard solu
28、tions respectively contains 1 4g and 0,1 4g of Hg. NOTEIn order to prevent pollution of waste water, collect solutions containing mercury salts and remove mercury following the instruction given in Annex B of ISO 5790. 5 Apparatus All new glassware or glassware not previously used for this determina
29、tion, including flasks used for reagents and samples, shall be washed as follows and rinsed with water after each operation: with a brush and soap if the walls are likely to be greasy; with nitric acid solution, approximately1,42g/ml; with a mixture, prepared at the time of washing, consisting of 4
30、volumes of sulphuric acidsolution, approximately 100 g/l solution and1 volume of the potassium permanganate solution (4.3).BS6075-11:1981 2 BSI 10-1999 Condition the glassware thus washed by carrying out several preliminary determinations of mercury using mercury standard solutions until satisfactor
31、y results are obtained before using it for actual determinations. Thereafter, use such glassware for mercury determination only. A typical apparatus incorporating an open-circuit measuring system (see 9.1) is shown in the Figure. It includes the following items. 5.1 Atomic absorption spectrometer, f
32、itted with a low-pressure mercury vapour lamp or a hollow-cathode lamp. NOTE 1Mercury hollow-cathode lamps have a relatively short life if used constantly. For this reason, but only with instruments which are not fitted with electrical source modulation, a low pressure mercury discharge lamp may be
33、preferred as a cheaper alternative. NOTE 2A suitable mercury vapour detector may be used as an alternative to the atomic absorption spectrometer. 5.2 Rapid-response recording instrument or maximum-deflection indicator. 5.3 Measuring cell, of length suitable for the spectrometer used (for example 1 o
34、r 10 cm) with windows transparent to ultraviolet light at a wavelength of about 253,7 nm. The enclosure containing the cell may be heated slightly (by means of an electric lamp or a radiant heater run below its rated voltage, etc.) in order to prevent condensation. 5.4 Gas washing bottles, capacity
35、approximately100ml, fitted with a pointed immersion tube and mark indicating a volume of60ml. Check that all such bottles give the same calibration graph. 5.5 Safety flask, capacity approximately 100 ml. The use of such a flask is optional. 5.6 Four-way stopcock 5.7 Needle valve 5.8 Pressure regulat
36、or 5.9 Flowmeter, measuring range 0 to 150 l/h. 5.10 Absorber, containing the iodine solution (4.6) for treatment of the exhaust gases containing mercury vapour. 6 Sampling Follow the procedure specified in ISO 3195, observing the additional precautions specified in 6.1 and 6.2. 6.1 Liquid products
37、As liquid products may contain small particles ofmetallic mercury, take a laboratory sample of about 1 litre at a place where the turbulence is sufficient to ensure, as far as possible, a representative sample. Take the test sample immediately from the laboratory sample and oxidize, at once, followi
38、ng the procedure specified in 7.1.1 and 7.4.1.1 in order to avoid loss of mercury through evaporation or adsorption. 6.2 Solid products The sampling of solid products involves no particular difficulty as such products are obtained by evaporation of sodium hydroxide solutions, which removes any volat
39、ile mercury. The only precautionary requirement is the immediate oxidation of the test solution prepared for the determination, in order to avoid loss of mercury. Take and treat the test portion following the procedure specified in 7.1.2 and 7.4.1.2. 7 Procedure WARNING For safety reasons, the gases
40、 leaving the measuring cell (5.3) shall pass through the absorber (5.10) containing the iodine solution (4.6). 7.1 Test portion 7.1.1 Liquid samples Weigh, to the nearest 0,1 g, a polyethylene flask of capacity 100 ml containing 10 ml of the potassium permanganate solution (4.3). Immediately after i
41、ts preparation (see 6.1), transfer approximately 50 ml of the test sample (6.1) into the flask and again weigh the flask and contents to the nearest 0,1 g (see9.2). Immediately follow the procedure specified in 7.4.1.1 (see 9.3). 7.1.2 Solid samples Into a 400 ml beaker, weigh, to the nearest 0,1 g,
42、 about 20 g of the test sample. Immediately follow the procedure specified in 7.4.1.2. 7.2 Blank test Carry out a blank test at the same time as the determination, following the same procedure and using the same quantities of all reagents used for the sampling and the determination, but omitting the
43、 test portion. 7.3 Preparation of the calibration graphs Prepare calibration graphs for two series of standard matching solutions containing 0 to 1 4g of mercury; 0 to 10 4g of mercury.BS6075-11:1981 BSI 10-1999 3 7.3.1 Preparation of standard matching solutions Into each of a series of twelve 100 m
44、l beakers, place40 ml of water, 1 ml of the sulphuric acid solution (4.2), 1 ml of the potassium permanganate solution (4.3) and the volumes of the appropriate standard mercury solutions (4.8) shown in the following table. Cover each beaker with a watch-glass, boil for a few seconds and allow to coo
45、l. 7.3.2 Spectrometric measurements Connect one of the gas washing bottles (5.4) containing 60 ml of water in the circuit. Adjust the apparatus, ensuring particularly that the gas flow rate air or the nitrogen (4.1) is set to about 60 l/h. Treat each standard matching solution separately and without
46、 interruption as follows. Reduce the excess permanganate by adding, drop by drop, the hydroxylammonium chloride solution (4.4) until decoloration takes place. Transfer the solution to one of the gas washing bottle (5.4) and dilute to60ml. Divert the gas flow and replace the gas washing bottle contai
47、ning water by that containing the standard matching solution. Add 2,0 ml of the tin(II) chloride solution (4.5), close the gas washing bottle immediately, shake it to mix the contents and restore the gas flow exactly 30 s after introducing the tin(II) chloride. Measure the peaks on the recording cha
48、rt or note the maximum deflections indicated, converting the values into absorbances, if necessary. 7.3.3 Plotting the graphs Plot two graphs corresponding to masses of mercury in the ranges 0 to 1,0 4g and 0 to 10 4g, having, for example, as abscissae the masses of mercury, expressed in micrograms,
49、 in the standard matching solutions and the corresponding values of the measured absorbances, less the measured value for the calibration blank solution (7.3.1 0 term), as ordinates. 7.4 Determination 7.4.1 Preparation of the test solution 7.4.1.1 Liquid samples Transfer the test portion (7.1.1) to a 600 ml beaker, add approximately 150 ml of water and allow to cool. Rinse the flask which contained the test portion, using 25 ml of the sulphuric acid solution (4.2) to which 2 drops of the hydroxylammonium chloride solution
