BS 7755-3 13-1998 Soil quality - Chemical methods - Determination of cadmium chromium cobalt copper lead manganese nickel and zinc in aqua regia extracts of soil - Flame and electr.pdf

1、BRITISH STANDARD BS 7755-3.13: 1998 ISO 11047: 1998 Incorporating Corrigendum No. 1 Soil quality Part 3: Chemical methods Section 3.13: Determination of cadmium, chromium, cobalt, copper, lead, manganese, nickel and zinc in aqua regia extracts of soil Flame and electrothermal atomic absorption spect

2、rometric methods ICS 13.080BS7755-3.13:1998 This British Standard, having been prepared under the directionof the Health and Environment Sector Board, waspublished under the authorityof the Standards Boardand comes into effect on 15 July 1998 BSI 05-1999 ISBN 0 580 29961 9 Amendments issued since pu

3、blication Amd. No. Date Comments 10120 Corr.No.1 July 1998 Title on front cover correctedBS7755-3.13:1998 BSI 05-1999 i Contents Page National foreword ii Foreword iii Text of ISO 11047 1BS7755-3.13:1998 ii BSI 05-1999 National foreword This British Standard reproduces verbatim ISO 11047:1998 and im

4、plements it as the UK national standard. The UK participation in its preparation was entrusted by Technical Committee EH/4, Soil quality, to Subcommittee EH/4/3, Chemical methods, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European

5、 committee any enquiries on the interpretation, or proposals for change, and keep the UKinterests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. BS

6、7755 is being published in a series of Parts subdivided into Sections and Subsections that will generally correspond to particular international standards. Other Parts of BS7755 are, or will be, as follows. Part 1: Terminology and classification; Part 2: Sampling; Part 3: Chemical methods; Part 4: B

7、iological methods; Part 5: Physical methods. Additional information Safety warning. This British Standard involves a considerable amount of pipetting, none of which should be done by mouth. The use of Grade A volumetric glassware where appropriate will give the best results when using this method. C

8、ross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electr

9、onic Catalogue. 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 immunity from legal obligations. Summary of pages This doc

10、ument comprises a front cover, an inside front cover, pages i and ii, theISO title page, pages ii to iv, pages 1 to 13 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 cov

11、er.BS7755-3.13-1998 ii BSI 05-1999 Contents Page Foreword iii 1 Scope 1 2 Normative references 1 3 Method A Determination of cadmium, chromium, cobalt, copper, lead, manganese, nickel and zinc by flame atomic absorption spectrometry 1 3.1 Principle 1 3.2 Reagents 2 3.3 Preparation of stock and stand

12、ard solutions of individual elements 3 3.4 Apparatus 4 3.5 Procedure 4 3.6 Determination of test portion 6 3.7 Calculation 6 3.8 Precision 6 3.9 Expression of results 7 3.10 Test report 7 4 Method B Determination of cadmium, chromium, cobalt, copper, lead, manganese, nickel and zinc by electrotherma

13、l atomic absorption spectrometry 7 4.1 Principle 7 4.2 Reagents 7 4.3 Stock and standard solutions 7 4.4 Apparatus 9 4.5 Procedure 9 4.6 Calibration and determination 10 4.7 Plotting the graph 11 4.8 Calculation 11 4.9 Expression of results 11 4.10 Precision 11 4.11 Test report 11 Annex A (informati

14、ve) Results of interlaboratory tests 12 Table 1 Indicative limits of soil contents (mg/kg dry matter) for elementsextractable in aqua regia in accordance with ISO 11446 1 Table 2 General analytical conditions for flame atomic absorptionspectrometry 2 Table 3 General conditions for electrothermal ato

15、mic absorptionspectrometry 8 Table A.1 Repeatability and precision of analysis for method A: Flame atomic absorption spectrometry 12 Table A.2 Repeatability and precision of analysis for method B: Electrothermal atomic absorption spectrometry 13 Descriptors: Soils, quality, soil testing, chemical an

16、alysis, determination of content, cadmium, chromium, cobalt, copper, lead, manganese, nickel, zinc.BS7755-3.13:1998 BSI 05-1999 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Inte

17、rnational Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison wi

18、th ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as a

19、n International Standard requires approval by atleast75% of the member bodies casting a vote. International Standard ISO 11047 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical methods and soil characteristics. Annex A of this International Standard is for inf

20、ormation only.iv blankBS7755-3.13:1998 BSI 05-1999 1 WARNING The procedures in this International Standard should be carried out by competent, trained persons. Some of the techniques and reagents, including the use of equipment, are potentially very dangerous. Users of this International Standard wh

21、o are not thoroughly familiar with the potential dangers and related safe practices should take professional advice BEFORE commencing any operation. 1 Scope This International Standard specifies two methods for the determination, by atomic absorption spectrometry, of one or more of cadmium, chromium

22、, cobalt, copper, lead, manganese, nickel and zinc, in aqua regia extracts of soil obtained in accordance with ISO11466. The choice of method for any element depends on the amount of that element expected to be in a sample, and both methods might be needed to cover all the elements in one sample. Th

23、e methods are applicable when the extractable element content is above or below the amount given in Table 1 (as milligrams per kilogram, dry matter), as appropriate. The two methods are described separately as follows: Method A Determination of cadmium, chromium, cobalt, copper, lead, manganese, nic

24、kel and zinc by flame atomic absorption spectrometry. Method B Determination of cadmium, chromium, cobalt, copper, lead, manganese, nickel and zinc by electrothermal atomic absorption spectrometry. Many of the procedures and reagents are common to both methods, and to the different elements within e

25、ach method. Users are advised, however, to read the whole standard carefully before embarking on any of the procedures. Table 1 Indicative limits of soil contents (mg/kg dry matter) for elements extractable in aqua regia in accordance with ISO 11446 NOTE 1Indicative limits given inTable 1 are approp

26、riate to the equipment and techniques avaiable at the time of publication of this International Standard. Technical improvements may change this position in the future. NOTE 2This International Standard refers specifically to the use of atomic absorption spectrometry. Users of this International Sta

27、ndard are advised to operate their laboratories to accepted quality control procedures. Certified Reference Materials (CRM) should be used to establish the amounts of the relevant elements in in-house reference materials. The latter can be used for routine quality control of the procedures given in

28、this International Standard. Results should be established with control charts, for each element, within the laboratory. No result should be accepted which falls outside an agreed limit. Quality control procedures based on a widely accepted statistical technique should be used to establish such limi

29、t, to ensure that these are stable and that no long-term drift is occurring. Certified Reference Materials should be used regularly to maintain the integrity of the in-house reference materials and, thereby, the quality control system. 2 Normative references The following standards contain provision

30、s which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possib

31、ility of applying the most recent editions of standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 3696:1987, Water for analytical laboratory use Specification and test methods. ISO 5725-1:1994, Accuracy (trueness and precision) of meas

32、urement methods and results Part1:General principles and definitions. ISO 11465:1993, Soil quality Determination of dry matter and water content on a mass basis Gravimetric method. ISO 11466:1994, Soil quality Extraction of trace elements soluble in aqua regia. 3 Method A Determination of cadmium, c

33、hromium, cobalt, copper, lead, manganese, nickel and zinc by flame atomic absorption spectrometry 3.1 Principle The method is based on the atomic absorption spectrometric measurement of the concentration of the element in an aqua regia extract of the sample, prepared in accordance with ISO 11466, us

34、ing the instrumental conditions given inTable 2. Element Method A (flame AAS) Method B (electrothermal AAS) Cadmium 2 12 12 5 15 2 12 2 2BS7755-3.13:1998 2 BSI 05-1999 Table 2 General analytical conditions for flame atomic absorption spectrometry 3.2 Reagents All reagents shall be of recognized anal

35、ytical grade. Use deionized water or water distilled from an all-glass apparatus, conforming to grade2 of ISO 3696. The water used for blank determinations and for preparing reagents and standard solutions shall have a concentration of the element to be determined that is negligible compared with th

36、e lowest concentration of that element in the sample solutions. 3.2.1 Hydrochloric acid, 37 %; 1,18g/ml The same batch of hydrochloric acid shall be used throughout the procedure. 3.2.2 Nitric acid, 65 %; 1,42g/ml The same batch of nitric acid shall be used throughout the procedure. 3.2.3 Nitric aci

37、d, diluted 1 + 3 (V/V) Add 250 ml of nitric acid (3.2.2) to500ml of water in a1000ml volumetric flask and fill to the mark with water. 3.2.4 Sulfuric acid, 98 %; 1,84g/ml. The same batch of sulfuric acid shall be used throughout the procedure. 3.2.5 Sulfuric acid, diluted1 + 9 (V/V). Add slowly with

38、 swirling or stirring (magnetic stirrer bar) 100ml of sulfuric acid (3.2.4) to700ml of water in a1000ml volumetric flask, mix, cool and fill to the mark with water. 3.2.6 Lanthanum chloride solution, 37g/l lanthanum. Dissolve100 g of lanthanum(III) chloride, LaCl 3 .7H 2 O, in700ml water. Then quant

39、itatively transfer it to a1000ml volumetric flask and fill to the mark with water. 3.2.7 Blank solution without lanthanum for calibration Dilute 210 ml of hydrochloric acid (3.2.1) and70ml of nitric acid (3.2.2) with500ml water in a1000ml volumetric flask and fill to the mark with water. 3.2.8 Blank

40、 solution with lanthanum for calibration Dilute 210 ml of hydrochloric acid (3.2.1) and70ml of nitric acid (3.2.2) with500ml water in a1000ml volumetric flask. Add100ml lanthanum chloride solution (3.2.6) and fill to the mark with water. 3.2.9 Acetone Element Wavelength (nm) Flame type Lanthanum chl

41、oride Main Interferences Background correction Cadmium 228,8 Oxidizing air/acetylene No Fe Deuterium Chromium 357,9 Reducing air/acetylene or acetylene/N 2 O Yes No Fe, Al Ca, Mg Halogen Cobalt 240,7 Oxidizing air/acetylene No Deuterium Copper 324,8 Oxidizing air/acetylene No Deuterium Lead 217,0 Ox

42、idizing air/acetylene No Deuterium Manganese 279,5 Oxidizing air/acetylene or acetylene/N 2 O Yes No Fe, Si Deuterium Nickel 232,0 Oxidizing air/acetylene No Fe Deuterium Zinc 213,9 Oxidizing air/acetylene No Deuterium NOTEThe wavelengths given are the most sensitive. Interferences are generally low

43、er if the nitrous oxide flame is used for determination of chromium and manganese. Users should be aware that small changes in gas volume ratios can have significant effects on the intensity of the analytical signal, and can also change the linearity of the instrument response. Also difference in ac

44、id strength, which will vary slightly from digest to digest, can have a measurable effect on some elements with some instruments especially if background correction is not used. Users should, therefore, familiarize themselves with these aspects of their instruments performance.BS7755-3.13:1998 BSI 0

45、5-1999 3 3.3 Preparation of stock and standard solutions of individual elements The stock solutions of all the elements shall be replaced after a maximum of one year, but the standard solutions shall be renewed monthly as a minimum. If stock solutions are prepared directly from metals, care needs to

46、 be taken to ensure that the metal used is free of surface oxide layers. Stock solutions of metals are available commercially, and may be used, but their use should be controlled by appropriate laboratory procedures which meet accepted good laboratory practice. Records shall be kept of such control

47、data. 3.3.1 Cadmium solutions WARNING Cadmium is highly toxic. Safety measures shall be taken to avoid ingestion. 3.3.1.1 Cadmium, stock solution corresponding to1000mg/l of cadmium. Weigh, to the nearest 0,0002g, approximately1,0000g of cadmium metal (minimum purity99,5%) and dilute it in a covered

48、250ml glass beaker with40ml of nitricacid(3.2.3). Then add100ml of water. Boil to expel nitrous fumes, cool, transfer to a1000ml volumetric flask and fill to the mark with water. 3.3.1.2 Cadmium, standard solution corresponding to20mg/l of cadmium. Pipette 20,00 ml of the stock cadmium solution(3.3.

49、1.1) into a1000ml volumetric flask. Add20ml of nitric acid (3.2.3) and fill to the mark with water. 3.3.2 Chromium solutions 3.3.2.1 Chromium, stock solution corresponding to1000mg/l of chromium. Dissolve 2,8290 g 0,0002 g of potassiumdichromate, K 2 Cr 2 O 7 , dried at130 C for24h, in a covered400ml glass beaker with40ml of water. Add5ml of sulfuric acid(3.2.4), cool, transfer to a1000ml volumetric flask and fill to the mark with water. 3.3.2.2 Chromium, standard solution corresponding to20mg/l of chro