1、Magnesium and its alloys Determination of lead and cadmium Magnsium et alliages de magnsium Dosage du plomb et du cadmium ISO 2011 Reference number ISO 11707:2011(E) First edition 2011-08-01 ISO 11707 INTERNATIONAL STANDARDISO 11707:2011(E)COPYRIGHT PROTECTED DOCUMENT ISO 2011 All rights reserved. U
2、nless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. IS
3、O copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2011 All rights reservedISO 11707:2011(E)Contents Page Foreword iv 1 Scope 1 2 Normative references . 1 3 Method A Matrix-matching
4、 method . 1 3.1 Principle . 1 3.2 Reagents 1 3.3 Apparatus 2 3.4 Procedure 2 3.5 Calibration . 3 3.6 Calculation 3 4 Determination Method B Extraction method 3 4.1 Principle . 3 4.2 Reagents 3 4.3 Apparatus 4 4.4 Procedure 4 4.5 Calibration . 5 4.6 Calculation 5 5 Test report . 6 Annex A (informativ
5、e) Inter-laboratory test results . 7 ISO 2011 All rights reserved 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 technic
6、al 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. ISO collaborates closely wi
7、th 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 technical committees is to prepare International Standards. Draft Inte
8、rnational 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 the possibility that some of the elements of this document ma
9、y be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 11707 was prepared by Technical Committee ISO/TC 79, Light metals and their alloys, Subcommittee SC 5, Magnesium and alloys of cast or wrought magnesium. ISO 11707:2011(E)iv ISO 20
10、11 All rights reservedINTERNATIONAL STANDARD ISO 11707:2011(E)Magnesium and its alloys Determination of lead and cadmium 1 Scope This International Standard specifies wet analytical methods for lead and cadmium. There are two methods for the simultaneous determination of lead and cadmium in magnesiu
11、m and its alloys. Method A uses a matrix- matching technique for unalloyed magnesium and its alloys by inductively coupled plasma/atomic emission spectrometry (ICP/AES) or flame atomic absorption spectrometry (FAAS). Method B uses an extraction method for magnesium alloys with pretreatment procedure
12、s. Generally, Method A is recommended; also, Method B is designated where the matrix-matching method cannot be adopted due to complicated preparation of the assay standard solutions or where the combination of solvent extraction and FAAS is useful for analysts. These methods are applicable to the de
13、termination of lead and cadmium in the ranges of mass fractions of 0,000 5 % to 0,04 % and 0,000 5 % to 0,07 %, respectively. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For un
14、dated references, the latest edition of the referenced document (including any amendments) applies. ISO 648:2008, Laboratory glassware Single-volume pipettes ISO 1042:1998, Laboratory glassware One-mark volumetric flasks 3 Method A Matrix-matching method 3.1 Principle The sample is dissolved in a mi
15、xture of nitric and hydrochloric acids and diluted to a suitable volume. Lead and cadmium are determined by ICP/AES or FAAS at the wavelengths noted in Table 1. Table 1 Spectral lines Element Wavelength nm ICP/AES FAAS Pb 220,353 217,0 Cd 228,802 228,8 3.2 Reagents During the analysis, unless otherw
16、ise stated, use only reagents of recognized analytical grade and distilled water or water of equivalent purity. The solution shall be freshly prepared. 3.2.1 Hydrochloric acid, : 1,17 g/mL, 35 % to 37 %. 3.2.2 Nitric acid, : 1,42 g/mL, 69 % to 71 %. ISO 2011 All rights reserved 13.2.3 Lead standard
17、solution (100 mg Pb/L). Weigh 0,25 g of lead (99,99 % or higher in purity) to the nearest 0,1 mg, dissolve in 30 mL of nitric acid (1 + 1), heat to complete exhaustion of brown-coloured NO xgas and cool it. Transfer the solution quantitatively to a calibrated 250 mL volumetric flask, then dilute to
18、the mark with water and mix. Using a volumetric pipette, transfer 10 mL of the prepared solution to a 100 mL volumetric flask, thus allowing a ten-fold dilution. Dilute to the mark with water and mix. Keep the flask at the same temperature throughout. 3.2.4 Cadmium standard solution (100 mg Cd/L). W
19、eigh 0,25 g of cadmium (99,99 % or higher in purity) to a digit of 0,1 mg, dissolve in 30 mL of nitric acid (1 + 1), heat to complete exhaustion of brown-coloured NO xgas and cool it. Transfer the solution quantitatively to a calibrated 250 mL volumetric flask, then dilute to the mark with water and
20、 mix. Using a volumetric pipette, transfer 10 mL of the prepared solution to a 100 mL volumetric flask, thus allowing a ten-fold dilution. Dilute to the mark with water and mix. Keep the flask at the same temperature throughout. 3.3 Apparatus All volumetric glassware shall be of class A and calibrat
21、ed in accordance with ISO 648 or ISO 1042, as appropriate. Ordinary laboratory apparatus is also acceptable. 3.3.1 Inductively coupled plasma/atomic emission spectrometry (ICP/AES). The ICP/AES used will be satisfactory after optimizing in accordance with the manufacturers instructions. 3.3.2 Flame
22、atomic absorption spectrometer (FAAS). The FAAS used will be satisfactory after optimizing in accordance with the manufacturers instructions. 3.4 Procedure 3.4.1 Mass of sample Weigh 1,0 g of the sample to a digit of 0,1 mg. 3.4.2 Preparation of sample solution Weigh out the sample and transfer it i
23、nto a 250 mL beaker. Add 20 mL of water. After a mixture of 15 mL of hydrochloric acid (3.2.1) and 5 mL of nitric acid (3.2.2) has been added slowly, cover the beaker with a watch- glass and heat it on a hotplate to complete dissolution. Take up the residue in 25 mL of water, warm gently to complete
24、 the solution and cool. Filter, if necessary, through a paper-pulp pad and wash the precipitate with a small amount of water. Add the washings to the sample solution. Transfer the solution to a 100 mL volumetric flask and dilute to the mark with water and mix. Spray the solution into ICP/AES plasma
25、or an AAS flame to measure the emission intensity or the absorbance of lead and cadmium therein. 3.4.3 Reagent blank test Add matrix elements, such as Mg, Al, Zn and other elements, so that the concentration of the major components are the same as those of the sample. Magnesium oxide (99.99 % or hig
26、her in purity), aluminum, zinc and other metals and compounds of high purities should be used. Carry out a blank test in parallel with the determination, following the same procedure and using the same quantities of all the reagents as with the sample. ISO 11707:2011(E)2 ISO 2011 All rights reserved
27、3.5 Calibration Weigh 1,658 g of magnesium oxide (99.99 % or higher in purity) and transfer it to a 250 mL beaker. Add 20 mL of water. After a mixture of 15 mL of hydrochloric acid (3.2.1) and 5 mL of nitric acid (3.2.2) has been added slowly, cover the beaker with a watch-glass. Heat it on a hotpla
28、te for complete dissolution. Add matrix elements, such as Mg, Al, Zn and other elements. Add 0 mL, 1 mL, 3 mL and 5 mL of lead (3.2.3) and cadmium (3.2.4) standard stock solutions to the beaker using volumetric pipettes, transfer the solutions to 100 mL volumetric flasks, dilute them to the mark wit
29、h water and mix. Spray them into ICP/AES plasma or an AAS flame and plot calibration curves by measuring emission or absorption strength at the wavelengths noted in Table 1. 3.6 Calculation Obtain the mass of lead and cadmium from the calibration curve prepared (3.5). Calculate the mass fractions of
30、 lead and cadmium according to the following equations. where w Pb , w Cd are the mass fractions of Pb and Cd in the sample, in percent (%); A 1 is the concentration of the element in the test solution, in milligrams per litre (mg/L); A 2 is the concentration of the element in the reagent blank solu
31、tion, in milligrams per litre (mg/L); V is the final dilution volume of the test solution, in millilitres (mL); m is the mass of sample weighed, in grams (g). 4 Determination Method B Extraction method 4.1 Principle Dissolve the sample in a mixture of nitric and hydrochloric acids, add ammonium citr
32、ate solution and adjust the pH of the solution with ammonia solution and nitric acid. Add potassium cyanide to separate lead and cadmium selectively from matrixes with diphenylthiocarbazone (dithizone) in chloroform and dilute to a suitable volume. Lead and cadmium are determined by ICP/AES or FAAS.
33、 4.2 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity. The solutions should be freshly prepared prior to use. 4.2.1 Nitric acid (1:1). 4.2.2 Nitric acid (1:10). 4.2.3 Ammonia solution (1:10
34、). ISO 11707:2011(E) ISO 2011 All rights reserved 34.2.4 Perchloric acid, : 1,54 g/mL, 60 to 62 %. 4.2.5 Ammonium citrate solution. Dissolve 250 g of ammonium citrate in 1 000 mL of water. 4.2.6 Sodium hydroxide solution. Dissolve 125 g of sodium hydroxide in 1 000 mL of water. 4.2.7 Potassium cyani
35、de solution. Dissolve 50 g of potassium cyanide in 500 mL of water. 4.2.8 Dithizone solution in chloroform (0,2 %). Dissolve 2 g of dithizone in 1 000 mL of chloroform. Prepare freshly just prior to use, and store in a brown bottle. Filter if necessary through a paper-pulp pad (5A) 1) . Inhalation a
36、nd ingestion of chloroform are harmful. WARNING Please wear gloves and safety glasses and use good ventilation. 4.2.9 Dithizone solution in chloroform (0,02 %). Dissolve 0,2 g of dithizone in 1 000 mL of chloroform. Prepare freshly just prior to use, and store in a brown bottle. Filter if necessary
37、through a paper-pulp pad (5A). 4.3 Apparatus 4.3.1 pH meter. 4.3.2 Flame atomic absorption spectrometer (FAAS). The FAAS used will be satisfactory after optimizing in accordance with the manufacturers instructions. 4.3.3 Inductively coupled plasma/atomic emission spectrometry (ICP/AES). The ICP/AES
38、used will be satisfactory after optimizing in accordance with the manufacturers instructions. 4.4 Procedure 4.4.1 Mass of sample Weigh 1,0 g of the sample to a digit of 0,1 mg. 4.4.2 Preparation of sample solution Weigh out the sample and transfer it into a 250 mL beaker. Add 20 mL of water. After a
39、 mixture of 15 mL of hydrochloric acid (3.2.1) and 5 mL of nitric acid (3.2.2) has been added slowly, cover the beaker with a watch- glass and heat it on a hotplate until complete dissolution. Add 30 mL of ammonium citrate solution (4.2.5) and dilute with water until the volume of the solution reach
40、s approximately 100 mL. Adjust the pH of the solution to alkaline with ammonia solution (4.2.3). 1) Paper-pulp pad (5A) is the trade name of a product supplied by ADVANTEC Co. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the
41、 product named. Equivalent products may be used if they can be shown to lead to the same results. ISO 11707:2011(E)4 ISO 2011 All rights reservedAdd 3 mL of potassium cyanide solution (4.2.7) and adjust the pH of the solution to 9,2 0,1 with ammonia solution (4.2.3) and nitric acid (4.2.2). Transfer
42、 the solution into a separating funnel. Add 20 mL of 0,2 % dithizone-chloroform (4.2.8) and shake it for 5 min. Allow to stand until separation of the chloroform layer and water layer is completed, which takes about 5 min. Transfer the lower layer of chloroform to a new beaker. Repeat the steps in t
43、he two previous paragraphs. Add the lower layer of chloroform to the sample solution. Add 10 mL of dithizone-chloroform (0,02 %) to a separating funnel and shake it again for 5 min. Allow to stand until separation of the layers is completed. Add the lower layer of chloroform to the sample solution a
44、gain. Heat the solution in a warm bath at 60 C to 80 C for complete evaporation of chloroform to dryness. Add 10 mL of nitric acid and 5 mL of perchloric acid to the dried beaker. Heat it to completely evaporate the liquids and dry the beaker. If the organic compounds are not fully decomposed, add 5
45、 mL of nitric acid. Add 20 mL of nitric acid (4.2.1) to the beaker, dissolve the deposited salts, boil it gently for 1 min to 2 min, and cool it to room temperature. Transfer the contents quantitatively to the calibrated 100 mL volumetric flask. Dilute to the marked line with water and mix. Spray th
46、e solution into ICP/AES plasma or an AAS flame and measure the emission intensity or the absorbance of lead and cadmium therein. 4.4.3 Reagent blank test Carry out a blank test in parallel with the determination, following the same procedure and using the same quantities of all the reagents as with
47、the sample. 4.5 Calibration Add 0 mL, 1 mL, 3 mL and 5 mL of lead (3.2.3) and cadmium (3.2.4) standard stock solutions to the beaker (see 3.5) using volumetric pipettes, and transfer the respective solutions to 100 mL volumetric flasks. Add 15 mL of nitric acid (3.2.2), dilute it to the marked line
48、with water and mix. Spray them into ICP/AES plasma or an AAS flame and plot calibration curves by measuring emission or absorption strength at the wavelengths noted in Table 1. 4.6 Calculation Obtain the mass of lead and cadmium from the calibration curve prepared (4.5). Calculate the mass fractions
49、 of lead and cadmium according to the following equations. ISO 11707:2011(E) ISO 2011 All rights reserved 5where w Pb , w Cd are the mass fractions in the sample, in percent (%); A 1 is the concentration of the element in the test solution, in milligrams per litre (mg/L); A 2 is the concentration of the element in the reagent blank solution, in milligrams per litre (mg/L); V is the fi
