1、BRITISH STANDARDBS ISO 20280:2007Soil quality Determination of arsenic, antimony and selenium in aqua regia soil extracts with electrothermal or hydride-generation atomic absorption spectrometryICS 13.080.10g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g
2、49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS ISO 20280:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee BSI 2008ISBN 978 0 580 53180 4National forewordThis British Standard is t
3、he UK implementation of ISO 20280:2007.The UK participation in its preparation was entrusted to Technical Committee EH/4, Soil quality.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary prov
4、isions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. Amendments/corrigenda issued since publicationDate Commentson 30 May 2008Reference numberISO 20280:2007(E)INTERNATIONAL STANDARD ISO20280First edi
5、tion2007-08-15Soil quality Determination of arsenic, antimony and selenium in aqua regia soil extracts with electrothermal or hydride-generation atomic absorption spectrometry Qualit du sol Dosage de larsenic, de lantimoine et du slnium dans des extraits du sol leau rgale par spectromtrie dabsorptio
6、n atomique avec atomisation lectrothermique ou gnration dhydrures BS ISO 20280:2007ii iiiContents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Principle. 1 4 Reagents 2 5 Apparatus 4 6 Procedure 5 6.1 Test portion . 5 6.2 Aqua regia extraction for arsenic, antimony and selenium . 5 6.3
7、Blank test solution 5 7 Method A Electrothermal atomic absorption spectrometry: Preparation of calibration solutions and measurement 5 7.1 General. 5 7.2 Calibration solutions for arsenic. 5 7.3 Calibration solutions for antimony . 5 7.4 Calibration solutions for selenium 6 7.5 Calibration and deter
8、mination with ETAAS measurement. 6 8 Method B Hydride-generation atomic absorption spectrometry: Preparation of calibration solutions and measurement. 7 8.1 Pre-reduction and calibration for the determination of arsenic 7 8.2 Pre-reduction and calibration for the determination of antimony . 7 8.3 Pr
9、e-reduction and calibration for the determination of selenium . 7 8.4 Measurement of calibration and test solutions by hydride-generation atomic absorption spectrometry . 8 9 Plotting the calibration graph 8 10 Calculation. 8 10.1 General. 8 10.2 Calculation according to the method of standard addit
10、ions 9 11 Expression of results . 9 12 Interferences . 9 13 Precision 10 14 Test report . 14 Bibliography . 15 BS ISO 20280:2007iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Inter
11、national 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 wit
12、h ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technica
13、l committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated 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
14、 the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 20280 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical methods and soil chara
15、cteristics. BS ISO 20280:20071Soil quality Determination of arsenic, antimony and selenium in aqua regia soil extracts with electrothermal or hydride-generation atomic absorption spectrometry WARNING Certain procedures, reagents and apparatus used in this International Standard pose hazards, especia
16、lly in connection with concentrated acids, toxic solutions of arsenic (As), antimony (Sb) and selenium (Se), and high-pressure gases. Users should ensure that they are familiar with the safety procedures necessary in such situations, and with any legal requirements (including waste disposal). If in
17、any doubt, seek advice from the competent authorities. 1 Scope This International Standard specifies methods for the determination of arsenic, antimony and selenium, in an aqua regia extract of soil obtained in accordance with ISO 11466, by electrothermal or hydride-generation atomic absorption spec
18、trometry. 2 Normative references The following referenced documents are indispensable for the 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, W
19、ater for analytical laboratory use Specification and test methods ISO 11464:2006, Soil quality 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 o
20、f trace elements soluble in aqua regia 3 Principle Arsenic, antimony and selenium are extracted from soil samples with aqua regia according to ISO 11466. Arsenic, antimony and selenium are determined by electrothermal atomic absorption spectrometry (ETAAS), in which discrete volumes of sample soluti
21、on are dispensed into a graphite tube. By increasing the temperature of this graphite tube stepwise, the processes of drying, thermal decomposition of the matrix and thermal dissociation into free atoms occur. The resulting absorption signal should (under optimum conditions) be a sharp symmetrical p
22、eak proportional to the element concentration in solution. Alternatively, arsenic, antimony and selenium are determined by the hydride-generation technique (HGAAS). Arsenic and antimony are first pre-reduced in the aqua regia extract by a mixture of ascorbic acid and potassium iodide. Selenium is pr
23、e-reduced by hydrochloric acid at an elevated temperature. After that, the hydride formation occurs by reaction with a sodium borohydride solution. The hydrides are carried from the solution by an argon stream into a heated quartz cell and decomposed at 900 C and then the atom concentration for arse
24、nic and antimony is measured by atomic absorption spectrometry. There are several commercial systems available where the reaction of hydride formation occurs continuously (continuous flow or BS ISO 20280:20072 flow injection systems) or stepwise (batch systems). All these techniques can be used, but
25、 adaptation of the working steps and reagent concentrations according to the advice of the manufacturer may be necessary. Refer to the manufacturers recommendation for wavelengths and spectral band widths or see Table 1. Table 1 Measurement conditions for arsenic, antimony and selenium Wavelength Sp
26、ectral band width Element nm nm Arsenic 193,7 0,7 Antimony 217,6 1,0 Selenium 196,0 1,0 4 Reagents All reagents shall be of recognised analytical grade. Use demineralised water or water distilled from an all-glass apparatus conforming to Grade 2 of ISO 3696. The water used for blank determinations a
27、nd for preparing reagents and standard solutions shall have element concentrations that are negligible compared with the lowest concentration to be determined in the sample solutions. 4.1 Hydrochloric acid, w(HCl) = 37 %, (HCl) 1,2 g/ml. The same batch of hydrochloric acid shall be used throughout t
28、he procedure. 4.2 Hydrochloric acid, diluted (1 + 9). Pour 500 ml of water into a 1 000 ml volumetric flask. Add 100 ml of hydrochloric acid (4.1) with caution, mix and fill to the mark with water. 4.3 Nitric acid, w(HNO3) = 65 %, (HNO3) 1,4 g/ml. The same batch of nitric acid shall be used througho
29、ut the procedure. 4.4 Nitric acid, c(HNO3) = 0,5 mol/l. Pour 500 ml of water into a 1 000 ml volumetric flask. Add 22 ml of nitric acid (4.3) with caution, mix and fill to the mark with water. 4.5 Aqua regia solution, diluted (1 + 9). Pour 500 ml of water into a 1 000 ml volumetric flask. Add 75 ml
30、of hydrochloric acid (4.1) and 25 ml of nitric acid (4.3) with caution, mix and fill to the mark with water. 4.6 Palladium/magnesium nitrate modifier solution. Two sources of modifier solutions can be used: commercially available modifier solutions; modifier element solutions prepared in the laborat
31、ory from pure palladium (e.g. powder) or from stochiometrically defined and dried salts. Dissolve 0,30 g of palladium nitrate Pd(NO3)2 and 0,36 g of magnesium nitrate Mg(NO3)26 H2O in a 100 ml volumetric flask, fill to the mark with 0,5 mol/l nitric acid (4.4) and mix. BS ISO 20280:20073Alternativel
32、y, prepare the palladium/magnesium nitrate modifier solution as follows: Dissolve, in a 250 ml beaker, 0,14 g of palladium powder in 3,5 ml of nitric acid (4.3) and add 10 l of hydrochloric acid (4.1). Evaporate the solution to near dryness on a water bath or hot plate, then add 0,36 g of magnesium
33、nitrate Mg(NO3)2 6 H2O. Dissolve this solid residue in 50 ml of nitric acid (4.4), transfer the solution into a 100 ml volumetric flask, fill to the mark with nitric acid (4.4) and mix. 10 l of this solution are equal to 14 g of Pd and 36 g of Mg(NO3)2. NOTE The recommendations of instrument manufac
34、turers may propose different modifier-solution concentrations. Also, recommendations of appropriate modifier-to-analyte ratios may be given depending on the furnace design. 4.7 Pre-reduction solutions, ascorbic acid and potassium iodide. Dissolve 10 g of potassium iodide (KI) and 10 g of ascorbic ac
35、id (C6H8O6) in 200 ml of water. This solution shall be prepared on the day of use. 4.8 Sodium borohydride solution. The composition of this solution depends on the hydride-generation system used. Generally, the concentration of sodium borohydride (NaBH4) varies from 0,2 g/l to 10 g/l, and the concen
36、tration of sodium hydroxide from 0,5 g/l to 5 g/l. Refer to the manufacturers instruction for further information. Dissolve an appropriate quantity of sodium hydroxide in water, add a quantity of sodium borohydride, wait until complete dissolution, filter the solution through a membrane filter of 0,
37、45 m porosity into a 1 000 ml volumetric flask, fill to the mark with water and mix. This solution should be prepared freshly on the day of use. 4.9 Preparation of stock and standard solutions of individual elements. Two sources of stock solutions are available: commercially available stock solution
38、s; stock solutions prepared in the laboratory from pure elements or stochiometrically defined dried salts or oxides. NOTE Commercially available stock solutions have the advantage that they remove the need to handle toxic metals. However, special care needs to be taken that these solutions are suppl
39、ied with a certified composition from a reputable source and are checked on a regular basis. WARNING Arsenic, antimony and selenium are highly toxic. Take appropriate measures to avoid ingestion. Care should be taken in disposal of such solutions. 4.10 Arsenic, stock solution corresponding to 1 000
40、mg/l of arsenic. 4.11 Arsenic, standard solution corresponding to 100 mg/l of arsenic. Pipette 10,0 ml of the arsenic stock solution (4.10) into a 100 ml volumetric flask, add 1 ml of nitric acid (4.3), fill to the mark with water and mix well. 4.12 Arsenic, standard solution corresponding to 1 mg/l
41、 of arsenic. Pipette 1,00 ml of the 100 mg/l arsenic standard solution (4.11) into a 100 ml volumetric flask, add 2 ml of nitric acid (4.3), fill to the mark with water and mix well. Prepare this solution at least weekly. 4.13 Antimony, stock solution corresponding to 1 000 mg/l of antimony. 4.14 An
42、timony, standard solution corresponding to 100 mg/l of antimony. Pipette 10,0 ml of the antimony stock solution (4.13) into a 100 ml volumetric flask, add 5 ml of nitric acid (4.3) and 10 ml of hydrochloric acid (4.1), fill to the mark with water and mix well. BS ISO 20280:20074 4.15 Antimony, stand
43、ard solution corresponding to 1 mg/l of antimony. Pipette 1,00 ml of the 100 mg/l antimony standard solution (4.14) into a 100 ml volumetric flask, add 2 ml of nitric acid (4.3) and 2 ml hydrochloric acid (4.1), fill to the mark with water and mix well. Prepare this solution at least weekly. 4.16 Se
44、lenium, stock solution corresponding to 1 000 mg/l of selenium. 4.17 Selenium, standard solution corresponding to 100 mg/l of selenium. Pipette 10,0 ml of the selenium stock solution (4.16) into a 100 ml volumetric flask, add 1 ml of nitric acid (4.3), fill to the mark with water and mix well. 4.18
45、Selenium, standard solution corresponding to 1 mg/l of selenium. Pipette 1,00 ml of the 100 mg/l selenium standard solution (4.17) into a 100 ml volumetric flask, add 2 ml of nitric acid (4.3), fill to the mark with water and mix well. Prepare this solution at least weekly. 4.19 1,10 Phenanthrolin-m
46、onohydrate solution. Dissolve 10 g of 1,10 phenanthrolin-monohydrate (C12H8N2H20) in 100 ml of water. The solution shall be prepared on the day of use. 5 Apparatus 5.1 General Usual laboratory apparatus should be used. Quartz vessels should be the preferred material for the whole procedure (especial
47、ly if lower calibration ranges (0,1 g/l to 1 g/l) are to be used for measurement). NOTE Cleaning of glassware: All glassware used must be cleaned carefully before use, e.g. by immersion in (HNO3) 50 ml/l aqueous nitric acid solution for a minimum of 6 h, followed by rinsing with water before use. It
48、 can be helpful to keep a separate set of glassware exclusively for these determinations. 5.2 Water bath. 5.3 Atomic absorption spectrometer, equipped with a hollow cathode of the element or, preferably, a high-energy discharge lamp (which gives a greater and more stable light intensity) operated at
49、 a current recommended by the lamp and instrument manufacturer, an automatic background-correction device, preferably Zeeman correction for ETAAS-measurement, and a computerised readout. 5.4 Electrothermal atomiser, equipped with an automated sample introduction system (sample dispenser), which should be adaptable to the atomic absorption spectrometer (5.3). 5.5 Hydride-generation system, commercially available, where the reaction occurs continuously (continuous flow or flow injection systems) or stepwise (batch s
