1、BRITISH STANDARD BS ISO 16772:2004 Soil quality Determination of mercury in aqua regia soil extracts with cold-vapour atomic spectrometry or cold-vapour atomic fluorescence spectrometry ICS 13.080.10 BS ISO 16772:2004 This British Standard was published under the authority of the Standards Policy an
2、d Strategy Committee on 17 June 2004 BSI 17 June 2004 ISBN 0 580 43956 9 National foreword This British Standard reproduces verbatim ISO 16772:2004 and implements it as the UK national standard. The UK participation in its preparation was entrusted by Technical Committee EH/4, Soil quality, to Subco
3、mmittee EH/4/3, Chemical methods, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the
4、BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible fo
5、r its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK int
6、erests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii and iii, a blank page, pages 1 to 8, an inside back cover and a back cover. The BSI copy
7、right notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO 16772:2004(E) OSI 4002INTERNATIONAL STANDARD ISO 16772 First edition 2004-06-01 Soil quality Determination of mercury in aqua regia soi
8、l extracts with cold- vapour atomic spectrometry or cold- vapour atomic fluorescence spectrometry Qualit du sol Dosage du mercure dans les extraits de sol leau rgale par spectromtrie dabsorption atomique de vapeur froide ou par spectromtrie de fluorescence atomique de vapeur froide BSISO16772:2004IS
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14、r iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for whic
15、h a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all ma
16、tters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circ
17、ulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held respons
18、ible for identifying any or all such patent rights. ISO 16772 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical methods and soil characteristics. BSISO16772:2004blank 4002:27761OSISBINTENRATIONAL TSANDADR IS:27761 O4002(E)I SO 4002 All irthgs ersedevr 1Soil qu
19、ality Determination of mercury in aqua regia soil extracts with cold-vapour atomic spectrometry or cold-vapour atomic fluorescence spectrometry WARNING Mercury is highly toxic. Safety measures shall be taken in handling mercury and mercury solutions. Mercury compounds should not be introduced into t
20、he environment. The laboratory handling these compounds should be aware of the relevant international and national legislation regulating the handling of mercury and its compounds. 1 Scope This International Standard specifies a method for the determination of mercury in an aqua regia extract of soi
21、l, obtained in accordance with ISO 11464 and ISO 11466, using cold-vapour atomic absorption spectrometry or cold-vapour atomic fluorescence spectrometry. The limit of determination of the method is at least 0,1 mg/kg. 2 Normative references The following referenced documents are indispensable for th
22、e application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3696:1987, Water for analytical laboratory use Specification and test methods ISO 11464:1994, Soil quali
23、ty Pretreatment of samples for physico-chemical analysis ISO 11465:1993, Soil quality Determination of dry matter and water content on a mass basis Gravimetric method ISO 11466:1995, Soil quality Extraction of trace elements soluble in aqua regia 3 Principle Mercury is reduced to the elemental state
24、 by tin(II) chloride solution and liberated from solution in a closed system. The mercury vapour passes through a cell positioned in the light path of an atomic absorption spectrometer. Its absorbance at a wavelength of 253,7 nm is measured. The absorbance signal is a function of mercury concentrati
25、on. Alternatively, after the reduction step, the mercury vapour is injected into the cell of an atomic fluorescence spectrometer, where the mercury atoms are excited by radiation of a specific wavelength. The intensity of the fluorescence radiation is a function of mercury concentration. NOTE Tin(II
26、) chloride as a reduction substance is specified in this International Standard because sodium borohydride reduces many elements common in soil extract solutions to the elemental state, which cause matrix problems under particular circumstances. BSISO16772:2004IS:27761 O4002(E) 2 I SO 4002 All irthg
27、s ersedevr4 Reagents and gases All reagents shall be of recognized analytical grade. Use deionized water or water distilled from an all-glass apparatus, complying with grade 2 as defined in ISO 3696. The water used for blank determinations, and for preparing reagents and standard solutions shall hav
28、e a mercury concentration that is negligible compared with the lowest calibration concentration, e.g. 10 times of the determination limit of the method. 4.1 Hydrochloric acid, w(HCl) = 37 %; c(HCl) 12 mol/l, (HCl) 1,18 g/ml. The same batch of hydrochloric acid should be used throughout the procedure
29、. 4.2 Nitric acid, w(HNO 3 ) = 65 %, c(HNO 3 ) 14,5 mol/l, (HNO 3 ) 1,40 g/ml. The same batch of nitric acid should be used throughout the procedure. When different batches of acids are used throughout the procedure, the blank shall be controlled for each batch. 4.3 Nitric acid, diluted solution (1+
30、4), c(HNO 3 ) 4 mol/l. Add slowly 250 ml of nitric acid (4.2) to 500 ml of water in a 1000 ml volumetric flask, mix and fill to the mark with water. 4.4 Aqua regia, diluted solution (1+9). Add 21 ml hydrochloric acid (4.1) and 7 ml nitric acid (4.2) to 500 ml of water in a 1000 ml volumetric flask,
31、mix and fill to the mark with water. 4.5 Tin(II) chloride solution, (SnCl 2 2H 2 O) = 100 g/l, c(Sn) = 0,443 mol/l. Dissolve 10 g of SnCl 2 2H 2 O in 30 ml of hydrochloric acid (4.1), transfer to a 100 ml volumetric flask and fill to the mark with water. The blank concentration of mercury can be red
32、uced by bubbling a stream of nitrogen through the solution for 30 min, if necessary. Prepare this solution on the day of use. NOTE Other concentrations of tin(II) chloride may be necessary using other systems. 4.6 Mercury, stock solution corresponding to (Hg) = 1000 mg/l. 4.6.1 General Two sources o
33、f stock solutions can be used: commercially available stock solutions (4.6.2); stock solutions prepared in the laboratory from elemental mercury (4.6.3). 4.6.2 Commercially available stock solutions Certified commercial stock solutions should preferably be used. Commercial as well as home-made stock
34、 solutions should be checked on a regular basis. NOTE Commercially available stock solutions have the advantage that they limit the need to handle toxic mercury. However, special care needs to be taken that these solutions are supplied with a certified composition from a reputable source. BSISO16772
35、:2004IS:27761 O4002(E) I SO 4002 All irthgs ersedevr 34.6.3 Stock solutions prepared in the laboratory from elemental mercury In a beaker covered with a watch glass, dissolve 100 mg 0,4 mg of mercury metal minimum purity w(Hg) = 99,99 % with 17 ml nitric acid (4.2). Dilute with water, boil gently to
36、 expel nitrous oxides, cool and transfer quantitatively into a 100 ml volumetric flask and fill to the mark with water. This solution is stable for at least six months. 4.7 Mercury, standard solution corresponding to (Hg) = 20 mg/l. Pipette 2 ml of the stock mercury solution (4.6) into a 100 ml volu
37、metric flask, add 10 ml nitric acid (4.3), mix and fill to the mark with water. 4.8 Mercury, standard solution corresponding to (Hg) = 0,2 mg/l. Pipette 1 ml of the standard mercury solution (4.7) into a 100 ml volumetric flask, add 10 ml of nitric acid (4.3), mix and fill to the mark with water. Pr
38、epare this solution on the day of use. Low-level mercury standard solutions should be stored in suitable silica flasks or use PFA or FEP bottles as mercury vapour diffuses through low density polyethene bottles. 4.9 Argon or nitrogen. Argon or nitrogen with a purity of 99,99% should be used as carri
39、er gases. For atomic fluorescence spectrometric techniques, argon is strongly recommended because the sensitivity is higher than with nitrogen. 5 Apparatus 5.1 Usual laboratory glassware. All glassware or PFA, FEP bottles shall be carefully cleaned for determinations involving trace elements, e.g. b
40、y immersion in aqueous nitric acid solution of 5 % volume fraction for a minimum of 6 h, followed by rinsing with water before use. The nitric acid shall be replaced each week. Grade B volumetric glassware is adequate for this analysis (see ISO 648 and ISO 1042). 5.2 Atomic absorption spectrometer (
41、AAS), equipped with a mercury hollow cathode or an electrodeless discharge lamp (which gives a greater light intensity) operated at a current recommended by the lamp and instrument manufacturer, and an automatic background correction device. 5.3 Atomic fluorescence spectrometer (AFS), equipped with
42、a specific mercury lamp, a fixed 254 nm filter and a photomultiplier tube for the detection of fluorescence radiation. Operate at a current recommended by the lamp and instrument manufacturer (see also EN 13506). 5.4 Cold-vapour generator, batch system or an automated flow injection analysis system
43、(FIAS), adaptable either to the atomic absorption spectrometer (5.2) or to the atomic fluorescence spectrometer (5.3), according to the detection technique used for the determination of mercury. A flow-controlled nitrogen or argon stream (4.9) is used as an inert carrier to transport mercury vapour
44、into the cell. Time-controlled addition of tin(II)-chloride reducing solution (4.5) in combination with automatic start of the read signal of the spectrometer is required. Systems with a 10 cm or longer silica cell path length with silica windows adapted for atomic absorption spectrometry (5.2) are
45、commercially available. In this case, the silica cell is electrically heated to a temperature of 50 C to 100 C to avoid condensation of water. For the atomic fluorescence spectrometer (5.3), condensation in the silica cell is avoided by inclusion of a high efficiency permeation drying tube in the de
46、tection system. If an automated system is used, where the reaction occurs continuously (FIAS), the concentration of tin(II) chloride solution, reaction time and the gas-liquid separator configuration shall be optimized due to the slow reaction kinetics of the reducing system. BSISO16772:2004IS:27761
47、 O4002(E) 4 I SO 4002 All irthgs ersedevrWARNING It is essential that the manufacturers safety recommendations be strictly observed. 6 Quality control Users of this International Standard are advised to operate their laboratories to accepted quality control procedures. Certified reference materials
48、(CRM) should be used to establish the amounts of mercury in in-house reference materials. The latter can be used for routine quality control of the procedures given in this International Standard. Results shall be established with control charts, within the laboratory. No result shall be accepted wh
49、ich falls outside an agreed limit. Quality control procedures based on widely accepted statistical techniques shall be used to establish such limits, to ensure that these are stable and that no long- term drift is occurring. CRMs should be used regularly to maintain the integrity of the in-house reference materials and, thereby, the quality control system. 7 Procedure 7.1 Test solution Transfer 10 ml of aqua
