1、INTERNATIONAL STANDARD 4058 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION .MEXJJYHAWHAR OPI-AHCnAUHR IlO CTAWAFlM3AUkiH.ORGANISATION INTERNATIONALE DE NORMALISATION Magnesium and its alloys - Determination of nickel - Photometric method using dimethylglyoxime Magn make up the volume to 1 000 ml and
2、 mix. 3.11 Bromine water, saturated solution at ambient temperature. The solution should be prepared 24 h before use. 3.12 Nickel, 1 g/l standard solution. Prepare this solution according to one of the following methods : 3.12.1 Weigh, to the nearest 0,001 g, 1 g of pure nickel (titre 99.7 % or more
3、) and transfer to a tall-form beaker of suitable capacity (600 ml, for example). 1 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IS0 4058-1977 (El Cover with a watch gl
4、ass, and add 10 ml of water and 10 ml of nitric acid solution (3.2). Allow the nickel to react slowly, heating gently, if necessary, to complete the attack. Once the reaction is finished, add 10 ml of hydrochloric acid (3.1) and evaporate, carefully, - to dryness (do not calcine). Repeat the treatme
5、nt with hydrochloric acid (3.1) once more, then take up the residue with water, heat to complete the dissolution of the salts, transfer quantitatively to a 1 000 ml volumetric flask, make up to volume and mix. 1 ml of this standard solution contains 1 mg of nickel (Ni). 3.12.2 Weigh, to the nearest
6、0,001 g, 6,730 g of nickel ammonium sulphate (NH,),S0,NiS04.6H,0. Dissolve in water, transfer the solution quantitatively to a 1 000 ml volumetric flask, make up to volume and mix. 1 ml of this standard solution contains 1 mg of nickel (Ni). 3.13 Nickel, 0,l g/l standard solution. Transfer 100,O ml
7、of standard nickel solution (3.121, to a 1 000 ml volumetric flask, make up to volume and mix. 1 ml of this standard solution contains 0,l mg of nickel (Nil. 3.14 Nickel, 0,005 g/l standard solution. Transfer 50,O ml of standard nickel solution (3.131, to a 1 000 ml volumetric flask, make up to volu
8、me and mix. 1 ml of this standard solution contains 0,005 mg of nickel (Nil. Prepare this standard solution at the moment of use. 3.15 Bromothymol blue, 1 g/l solution in ethanol. Dissolve 0,l g of bromothymol blue in 5 ml of 95 % (V/v) ethanol, make up the volume to 100 ml with water and mix. 4 APP
9、ARATUS Usual laboratory apparatus, and 4.1 Spectrophotometer, or 4.2 Electrophotometer. 5 SAMPLING 5.1 Laboratory sample) 5.2 Test sample Chips not more than 1 mm thick shall be obtained by milling or drilling. 6 PROCEDURE 6.1 Test portion Weigh, to the nearest 0,001 g, about 1 g of the test sample
10、(5.2). 6.2 Blank test Carry out a blank test in parallel with the analysis, following the same procedure and using the same quantities of all reagents as are used in the analysis. 6.3 Preparation of the calibration curve 6.3.1 Preparation of standard matching solutions, related to photometric measur
11、ements carried out with an optical path length of 2 cm Into a series of seven 50 ml volumetric flasks, transfer the volumes of standard nickel solution (3.14) indicated in table 1. TABLE 1 Volume of standard nickel solution (3.14) ml Corresponding mass of nickel (Ni) w 0 * 1.0 2.0 530 10,o I 15.0 20
12、,o 0 0,005 0,010 0,025 0,050 0,075 0,100 * Compensation solution. Then add to each volumetric flask 20 ml of hydrochloric acid (3.10) and the quantity of water necessary to obtain about 40 ml. 1) Sampling from supply lots will be the subject of a future International Standard. 2 Copyright Internatio
13、nal Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IS0 4058-1977 (E) 6.3.2 Colour reaction Add 1 ml of bromine water (3.11) and wait for at least 15 min. Add slowly, while stirring, ammonia sol
14、ution (3.6) until the colour disappears and then add an excess of 2 ml. Cool the solution to a temperature below 30 OC. Finally, add 2 ml of dimethylglyoxime solution (3.71, make up to volume and mix. 6.3.3 Photometric measurements Measure the absorbance of each solution after IO min, but not more t
15、han 30 min, using the spectrophotometer (4.1) at the maximum of the absorption curve (wavelength approximately 445 nm) or with the electrophotometer (4.2) fitted with suitable filters, after having adjusted the apparatus to zero absorbance against the compensation solution. 6.3.4 Plotting of the cal
16、ibration curve Plot a graph showing, for example, the amounts of nickel (Nil, expressed in milligrams, contained in 50 ml of standard matching solution as abscissae, and the corresponding absorbance values as ordinates. 6.4 Detemrination 6.4.1 Preparation of the test solution Transfer the test porti
17、on (6.1) to a beaker of suitable capacity (for example 250 ml), and cover it with a watch glass. Add 25 ml of water and, in small portions, 7,5 ml of hydrochloric acid (3.1) and 2 ml of nitric acid (3.2). Once the reaction is finished, heat to boiling and boil for 2 or 3 min. Filter if necessary. Al
18、low to cool to ambient temperature. According to the presumed nickel content, operate on the whole of the test solution or, having brought the volume of this solution up to 100 ml, operate on the aliquot indicated in table 2. TABLE 2 Volume of aliquot of Presumed nickel Volume of the test content th
19、e test sulution Quantity of nickel solution for the present colour reaction % (m/m) ml ml w rom 0,000 5 to 0,Ol - whole from 0,005 to 0.10 rom 0,Ol to 0,02 100 50 from 0,05 to 0,lO rom 0.02 to 0,05 100 20.0 from 0,04 to 0.10 J Transfer the aliquot of the test solution to a beaker of suitable capacit
20、y (for example 250 ml). In all cases bring the volume of the solution to about 40 ml by evaporation or dilution. Add 5 ml of hydroxylammonium chloride solution (3.3), 20 ml of citric acid solution (3.41, 10 ml of thiourea solution (3.5) and 3 to 5 drops of bromothymol blue solution (3.15). Add slowl
21、y the ammonia solution (3.6) until the indicator turns blue and then add an excess of 0,5 ml. Add 5 ml of dimethylglyoxime solution (3.7) and transfer the solution quantitatively to a separating funnel of suitable capacity (for example 200 ml). Cool the solution before extraction. 6.4.2 Extraction o
22、f the nickel-dimethylglyoxime complex Add to the separating funnel 10 ml of chloroform (3.8) and shake carefully for 1 min. Allow to settle, draw off the organic phase and collect it in a second separating funnel of suitable capacity (for example 100 ml). Add to the funnel containing the aqueous pha
23、se 1 or 2 ml of chloroform (3.8) and, without shaking, draw off the organic phase and add it to that contained in the second separating funnel. Add once more to the aqueous phase 5 ml of chloroform (3.81, shake for 30 s, allow to settle, draw off the organic phase and collect it in the second separa
24、ting funnel, proceeding as already indicated. Discard the aqueous phase. Add to the organic phase 20 ml of ammonia solution (3.9) and shake for 30 s. Allow to settle, draw off the organic phase and place it in a third separating funnel of suitable capacity (for example 100 ml), washing with 1 or 2 m
25、l of chloroform (3.8). Add to the funnel containing the aqueous phase 5 ml of chloroform (3.8) and shake for 30 s. Allow to settle, draw off the organic phase and add it to that contained in the third funnel. Discard the aqueous phase. 6.4.3 Passage of the nickel complex into aqueous solution Add to
26、 the separating funnel containing the organic phase 10 ml of hydrochloric acid (3.10) and shake, carefully, for 1 min, allow to settle, draw off the organic phase and collect it in another separating funnel of suitable capacity (for example 100 ml). Add to the funnel containing the aqueous phase 1 o
27、r 2 ml of chloroform (3.8) and, without shaking, draw it off and add to the funnel containing the organic phase. Repeat once more the treatment of the organic phase with 10 ml of hydrochloric acid (3.101, still collecting the aqueous phase in the same separating funnel. Discard the organic phase. Ad
28、d to the aqueous phase 5 ml of chloroform (3.8) and shake for 30s. Allow to settle, draw off carefully the organic phase and discard it. Continue according to the procedure described in 6.3.2. 6.4.4 Photometric measurements Measure the absorbance of each solution after 10 min but not more than 30 mi
29、n, using the spectrophotometer (4.1) at the maximum of the absorption curve (wavelength approximately 445 nmj or with the electrophotometer (4.2) fitted with suitable filters, after having adjusted the apparatus to zero absorbance against the compensation solution. 3 Copyright International Organiza
30、tion for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IS0 4058-1977 (El 7 EXPRESSION OF RESULTS By means of the calibration curve (see 6.3.4), determine the quantity of nickel corresponding to the value of th
31、e photometric measurement. The content of nickel (Nil is given, as a percentage by mass, by the formula : (m, -myI x D 10 xm, where D is the ratio of the volume of the test solution to the volume of the aliquot taken for the colour reaction. m, is the mass, in grams, of the test portion; m, is the m
32、ass, in milligrams, of nickel found in the test solution or in the aliquot of the test solution; m2 is the mass, in milligrams, of nickel found in the corresponding blank test solution or in the aliquot of the blank test solution; 8 TEST REPORT The test report shall include the following particulars
33、 : a) the reference of the method used; b) the results and the form in which they are expressed; c) any unusual features noted during thedetermination; d) any operation not included in this International Standard, or regarded as optional. 4 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
