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1、INTERNATIONAL STANDARD 4058 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION .MEXJJYHAWHAR OPI-AHCnAUHR IlO CTAWAF lM3AUkiH.ORGANISATION INTERNATIONALE DE NORMALISATION Magnesium and its alloys - Determination of nickel - Photometric method using dimethylglyoxime Magn make up the volume to 1 000 ml an
2、d 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 mor
3、e) 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 ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 01:45:23 MDTNo reproduction or networking perm
4、itted without license from IHS -,-,- IS0 4058-1977 (El Cover with a watch glass, 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)
5、 and evaporate, carefully, - to dryness (do not calcine). Repeat the treatment 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 s
6、tandard solution contains 1 mg of nickel (Ni). 3.12.2 Weigh, to the nearest 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 m
7、g of nickel (Ni). 3.13 Nickel, 0,l g/l standard solution. Transfer 100,O ml 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 stan
8、dard nickel solution (3.131, to a 1 000 ml volumetric flask, make up to volume 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 o
9、f 95 % (V/v) ethanol, make up the volume to 100 ml with water and mix. 4 APPARATUS 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
10、6.1 Test portion Weigh, to the nearest 0,001 g, about 1 g of the test sample (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.
11、3.1 Preparation of standard matching solutions, related to photometric measurements 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
12、 (3.14) ml Corresponding mass of nickel (Ni) w 0 * 1.0 2.0 530 10,o I 15.0 20,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 w
13、ill be the subject of a future International Standard. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 01:45:23 MDTNo reproduction or networking permitted without license from
14、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 solution (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 dimethy
15、lglyoxime 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 than 30 min, using the spectrophotometer (4.1) at the maximum of the absorption curve (wavelength approximately 445 nm) or with the electrophotometer
16、 (4.2) fitted with suitable filters, after having adjusted the apparatus to zero absorbance against the compensation solution. 6.3.4 Plotting of the calibration curve Plot a graph showing, for example, the amounts of nickel (Nil, expressed in milligrams, contained in 50 ml of standard matching solut
17、ion as abscissae, and the corresponding absorbance values as ordinates. 6.4 Detemrination 6.4.1 Preparation of the test solution Transfer the test portion (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 o
18、f 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. Allow to cool to ambient temperature. According to the presumed nickel content, operate on the whole of the test solution or, having brought the volum
19、e 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 the 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
20、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 capacity (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 chlori
21、de 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 slowly 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 transf
22、er the solution quantitatively to a separating funnel of suitable capacity (for example 200 ml). Cool the solution before extraction. 6.4.2 Extraction of 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 of
23、f 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 phase 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
24、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 separating 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
25、. 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 ml 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 org
26、anic 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 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
27、 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 or 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 t
28、he organic phase with 10 ml of hydrochloric acid (3.101, still collecting the aqueous phase in the same separating funnel. Discard the organic phase. Add 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 ac
29、cording 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 min, using the spectrophotometer (4.1) at the maximum of the absorption curve (wavelength approximately 445 nmj or with the electrophotometer (4.2) fi
30、tted with suitable filters, after having adjusted the apparatus to zero absorbance against the compensation solution. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 01:45:23 M
31、DTNo 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 the photometric measurement. The content of nickel (Nil is given, as a perc
32、entage 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 mass, in milligrams, of nickel found in the test solution or in the aliquo
33、t 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 : a) the reference of the method used; b) the results and the form in wh
34、ich 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 ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 01:45:23 MDTNo reproduction or networking permitted without license from IHS -,-,-