ISO TS 16727-2013 Soil quality - Determination of mercury - Cold vapour atomic fluorescence spectrometry (CVAFS)《土质 汞的测定 冷蒸汽原子荧光光谱法(CVAFS)》.pdf

1、 ISO 2013 Soil quality Determination of mercury Cold vapour atomic fluorescence spectrometry (CVAFS) Qualit du sol Dosage du mercure Spectromtrie de fluorescence atomique vapeur froide (CVAFS) TECHNICAL SPECIFICATION ISO/TS 16727 First edition 2013-09-15 Reference number ISO/TS 16727:2013(E) Correct

2、ed version 2013-10-01 ISO/TS 16727:2013(E)ii ISO 2013 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2013 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photoc

3、opying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09

4、47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ISO/TS 16727:2013(E) ISO 2013 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 Principle 1 4 Interferences 1 5 Reagents 2 6 Apparatus . 3 6.1 Usual laboratory apparatus . 3 6.2

5、Atomic fluorescence spectrometer (AFS) 3 6.3 Automated sample introduction system . 3 7 Procedure. 4 7.1 Test sample solution 4 7.2 Test blank solution 4 7.3 Preparation of the calibration solutions . 4 7.4 Calibration 4 7.5 Measurement of test sample 4 8 Calculation and expression of results . 5 8.

6、1 Calculation 5 8.2 Expression of results 5 9 Test report . 5 Bibliography 6 ISO/TS 16727:2013(E) Foreword 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 ca

7、rried 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 with ISO, also take part in the work

8、. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the diffe

9、rent approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document ma

10、y be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/paten

11、ts). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO princip

12、les in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical methods and soil characteristics. In this corrected version, the status of the document was am

13、ended to Technical Specification on the cover page. In addition, the page headings were changed to ISO/TS 16727:2013(E).iv ISO 2013 All rights reserved ISO/TS 16727:2013(E) Introduction ISO/TS 16727 is based upon CEN/TS 16175-2, Sludge, treated biowaste and soil Determination of mercury Part 2: Cold

14、 vapour atomic fluorescence spectrometry (CV-AFS), which was developed by CEN/TC 400, Project Committee Horizontal standards in the fields of sludge, biowaste and soil. ISO 2013 All rights reserved v Soil quality Determination of mercury Cold vapour atomic fluorescence spectrometry (CVAFS) WARNING P

15、ersons using this Technical Specification should be familiar with usual laboratory practice. This Technical Specification does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices

16、 and to ensure compliance with any national regulatory conditions. IMPORTANT It is absolutely essential that tests conducted according to this Technical Specification be carried out by suitably trained staff. 1 Scope This Technical Specification specifies a method for the determination of mercury in

17、 aqua regia or nitric acid digests of sludge, treated biowaste and soil, obtained according to ISO 11466 or ISO 16729 using cold vapour atomic fluorescence spectrometry. The lower working range limit is 0,003 mg/kg (dry matter). 2 Normative references The following documents, in whole or in part, ar

18、e normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 114 65, Soil quality Determination of dry matter an

19、d water content on a mass basis Gravimetric method ISO 11466, Soil quality Extraction of trace elements soluble in aqua regia ISO 16729, Soil quality Digestion of nitric acid soluble fractions of elements ISO 3696, Water for analytical laboratory use Specification and test methods 3 Principle Monova

20、lent and divalent mercury is reduced to the elemental form by tin(II)-chloride solution or sodium borohydride in acid medium. Elemental mercury is stripped off from the solution in a closed system, by means of a stream of argon or nitrogen. The mercury vapour is injected into the cell of an atomic f

21、luorescence spectrometer where the mercury atoms are excited by radiation of a specific wavelength, usually about 254 nm. The intensity of the fluorescence radiation is a function of mercury concentration. The concentrations are calculated using a calibration curve. NOTE The matrix of the solution a

22、nalysed is dominated by the acids used in the digestion step. Tin(II)-chloride as a reduction substance is recommended in this Technical Specification, because sodium borohydride reduces many elements commonly found in soil, sludge and waste extract solutions, to the elemental state, which may cause

23、 matrix problems under particular circumstances. However, it is still possible to use sodium borohydride as reduction agent. The concentration range 0,1 g/l to 10 g/l in the digested solution, corresponding to 0,003 g/g to 0,3 g/g of mercury, when a 3,0 g of sample has been digested, can be determin

24、ed directly. Higher concentrations can be determined if the digested solution is diluted. Sensitivity can be increased by the amalgamation technique. 4 Interferences The presence of water vapour or aerosol in the fluorescence cell may cause suppression due to quenching. Water vapour should be remove

25、d from the carrier gas stream using a hygroscopic membrane before entering the detector. The noble metals, such as gold and silver, amalgamate with mercury and, TECHNICAL SPECIFICATION ISO/TS 16727:2013(E) ISO 2013 All rights reserved 1 ISO/TS 16727:2013(E) therefore, may cause suppression. Also ani

26、ons, for instance sulfide, iodide and bromide, which complex strongly with mercury, can cause suppression. Less interferences arise from heavy metals when tin(II)chloride is used rather than sodium borohydride. When flow systems are used, interference effects due to heavy metals may be less than ind

27、icated in Table 1. Table 1 Tolerable concentrations of some matrix elements Element Acceptable concentration mg/l Cu(II) 500 Ni(II) 500 Ag(I) 1 5 Reagents For the determination of mercury at trace and ultra-trace level, the reagents shall be of adequate purity. The concentration of mercury or interf

28、ering substances in the reagents and the water should be negligible compared to the lowest concentration to be determined. 5.1 Water quality 2 according to ISO 3696 for all sample preparations and dilutions. 5.2 Hydrochloric acid, HCl, (HCl) 1,17 g/ml, c(HCl) 12 mol/l, w(HCl) 370 g/kg. The same batc

29、h of hydrochloric acid shall be used throughout the procedure. 5.3 Nitric acid, HNO 3 , (HNO 3 ) 1,4 g/ml, c(HNO 3 ) 15 mol/l w(HNO 3 ) 650 g/kg. The same batch of nitric acid shall be used throughout the procedure. 5.4 Nitric acid, diluted solution (1 + 9). Add 100 ml of nitric acid (5.3) to 500 ml

30、 of water in a 1 000 ml volumetric flask, mix and fill to the mark with water 5.5 Nitric acid, rinsing solution for glassware, 2 mol/l. Add 150 ml of nitric acid (5.3) to about 500 ml of water, and dilute with water to 1 000 ml. 5.6 Aqua regia, diluted solution (1 + 9). Add 21 ml of hydrochloric aci

31、d (5.2) and 7 ml of nitric acid (5.3) to 500 ml of water in a 1 000 ml volumetric flask, mix and fill to the mark with water. 5.7 Tin(II)chloride solution, (SnCl 2 2 H 2O) = 100 g/l. Dissolve 10 g of SnCl 2 2 H 2 O in 30 ml of hydrochloric acid (5.2), transfer to a 100 ml volumetric flask and fill t

32、o the mark with water. The blank concentration of mercury can be reduced by bubbling a stream of nitrogen through the solution for 30 min, if necessary. Prepare this solution on the day of use. A solution of lower concentration, e.g. 0,5 g in 100 ml, may be used with flow systems. Prepare this latte

33、r solution freshly on the day of use from the more concentrated solution by diluting with water.2 ISO 2013 All rights reserved ISO/TS 16727:2013(E) 5.8 Sodium borohydride solution, NaBH 4 , 30 g/l. 1 g of sodium hydroxide, NaOH, is weighed into a 100 ml volumetric flask and dissolved in water. 3 g o

34、f sodium borohydride, NaBH 4 , is weighed and dissolved in the sodium hydroxide solution, then diluted to the mark with water. 5.9 Mercury standard stock solution, 1 000 mg/l Use a commercially available quantitative stock solution with a mercury concentration of (1 000 2) mg/l. This solution is con

35、sidered to be stable for at least one year, but in reference to guaranteed stability, see the recommendations of the manufacturer. 5.10 Mercury, standard solution I, 100 mg/l. Pipette 10 ml of the stock mercury solution (5.9) into a 100 ml volumetric flask, add 10 ml of nitric acid (5.3), mix and fi

36、ll to the mark with water. This solution is stable for one month. 5.11 Mercury, standard solution II, 1 mg/l. Pipette 1 ml of the mercury standard solution I (5.10) into a 100 ml volumetric flask, add 10 ml of nitric acid (5.3), mix and fill to the mark with water. This solution is stable for 7 days

37、. 5.12 Mercury, standard solution III, 100 g/l. Pipette 10 ml of the mercury standard solution II (5.11) into a 100 ml volumetric flask, add 10 ml of nitric acid (5.3), mix and fill to the mark with water. This solution shall be freshly prepared on the day of use. 5.13 Argon, with a purity of 99,99

38、%. 6 Apparatus 6.1 Usual laboratory apparatus All glassware shall be carefully cleaned as usual for low trace element determinations, e.g. by immersion in nitric acid rinsing solution (5.5) for a minimum of 6 h, followed by rinsing with water before use. The nitric acid shall be replaced each week.

39、6.2 Atomic fluorescence spectrometer (AFS) Equipped with a specific Hg lamp, a fixed 254 nm filter, a photomultiplier tube for the detection of fluorescence radiation and a suitable software for processing the output signal. Operate at a current recommended by the lamp or the instrument manufacturer

40、. The gas supply (argon or nitrogen) should be equipped with a two stage regulator. The use of a gas purifier consisting of activated carbon is recommended. Nitrogen gas will cause reduced sensitivity compared to argon. 6.3 Automated sample introduction system Automated mercury flow systems (flow in

41、jection systems or continuous flow systems) are very common for atomic fluorescence spectrometry. They allow a concentration range lower by about one order of magnitude. Manually operated systems or semi-automated batch systems are adequate as well. ISO 2013 All rights reserved 3 ISO/TS 16727:2013(E

42、) 6.4 Cold-vapour generator, batch system or an automated flow injection analysis system (FIA) The system should be adaptable to the atomic fluorescence spectrometer (6.2). A flow-controlled argon stream (5.13) is used as an inert carrier to transport mercury vapour into the cell. Time-controlled ad

43、dition of tin(II)-chloride reducing solution (5.7) in combination with automatic start of the read signal of the spectrometer is required. For the atomic fluorescence spectrometer ( 6.2), condensation in the cell is avoided by the inclusion of a drying tube in the detection system. If an automated s

44、ystem is used, where the reaction occurres continuously (FIA-System), the concentration of stannous chloride solution, reaction time and the gas-liquid separator configuration shall be optimised due to the slow reaction kinetics of the reducing system. 7 Procedure 7.1 Test sample solution The test s

45、ample solution is an aliquot of the particle free digest or extraction solution prepared according to ISO 11466 or ISO 16729. 7.2 Test blank solution Prepare a test blank solution at the same time as the extraction with aqua regia or nitric acid following the sample procedure, using the same quantit

46、ies of all reagents for the determination, but omitting the test sample. Transfer 10 ml of the test blank solution to a 100 ml volumetric flask and fill to the mark with water. 7.3 Preparation of the calibration solutions Before each batch of determinations, prepare a calibration blank solution and

47、from the 100 g/l mercur y standard solution III (5.12) at least five calibration solutions covering the range of concentrations to be determined. Pipette 0 ml, 1 ml, 2 ml, 5 ml, 10 ml and 20 ml of mercury standard solution III (5.12) into a series of 100 ml volumetric flasks. Fill to the mark with d

48、iluted nitric acid solution (5.4) or diluted aqua regia solution (5.6) and mix well. These solutions correspond to mercury concentrations of 1 g/l, 2 g/l, 5 g/l, 10 g/l and 20 g/l, respectively. Using 10 ml of each solution for the cold-vapour generator these solutions correspond to 10 ng, 20 ng, 50

49、 ng, 100 ng and 200 ng of mercury, respectively. 7.4 Calibration Set up the atomic fluorescence spectrometer (6.2) and the cold-vapour generator (6.4) according to the manufacturers instructions. Adjust the measuring cell, the gas flow and the flow rate of stannous chloride or sodium borohydride. Wait until the system is in equilibrium. Aspirate a blank and start the measurement procedure. The signal should be negligible. 7.5 Measurement of test sample Transfer 10 ml of test blank solution