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1、International Standard (! 6835 0 a 4 4 : j ;! I i 3 : ! $yy$p;jf j f; d: the filtrate shall be as clear as possible to avoid any subsequent blocking. Wash the filled ion-exchange column (5.81 with water until the washings are neutral. By means of a pipette (5.31, transfer 25 ml of the filtrate to th
2、e reservoir of the column and allow it to flow through the column at a rate of 1 to 1,5 ml/min, collecting the eluate in a 150 ml tall-form beaker. Wash the column three times with 25 ml portions of water, allowing the water to flow at a rate of 1 to 1,5 ml/min, and collect the washings in the beake
3、r. Regenerate the resin after each passage of the test solution by passing 100 ml of hydrochloric acid solution diluted (1 + 41, l volume of hydrochloric acid (e2c approximately 1,18 g/ml) + 4 volumes of water, at a rate of 1 to 1,5 ml/min, and washing with water, at the same rate, until the washing
4、s have a pH equal to or greater than 5. When not in use, the column should be filled with hydrochloric acid solution diluted (1 + 4). 7.2.3 Titration By means of the magnetic stirrer (5.10), stir the eluate in the beaker and adjust the pH to 580 f 0,05, checking by means of the pH-meter (5.5) fitted
5、 with the electrodes (5.6 and 5.7). using, as appropriate, the hydrochloric acid solutions (4.2 and 4.31, or the sodium hydroxide solutions (4.4 and 4.5). Add 12 g of the D-mannitol (4.1). After stirring for 1 min, titrate with the sodium hydroxide solu- tion (4.71, using the burette (5.41, until a
6、pH of 580 It 0,05 is obtained, measured using the normal scale, then the extended scale, of the pH-meter. . I) A suitable resin is available commercially. Details may be obtained from the Secretariat of ISO/TC 91 (AFNOR) or IS0 Central Secretariat. 2) Suitable apparatus is available commercially. De
7、tails may be obtained from the Secretariat of ISO/TC 91 (AFNORI or IS0 Central Secretariat. 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 07:39:50 MDTNo reproduction or netwo
8、rking permitted without license from IHS -,-,- IS0 6835-1981 (E) The volume of the sodium hydroxide solution used to return to the initial pH of 5,8 corresponds to the quantity of boric acid present in the aliquot portion. 8 Expression of results 8.1 Method of calculation The boron oxide content, ex
9、pressed as a percentage by mass, is given by the formula Vx c x 0.0348 1000 xxmo m 200 25 = vxcx 174 m where V is the volume, in millilitres, of the sodium hydroxide solution (4.71, used for the titration of the 25 ml aliquot por- tion of the test solution (7.2.1); c is the exact concentration, in m
10、oles of NaOH per litre, of the sodium hydroxide solution (4.7); m is the mass, in grams, of the test portion (7.1); 0,084 8 is the mass, in grams, of boron oxide correspon- ding to 1 ml of exactly 1 mol/l sodium hydroxide solution. By replacing c in the above formula by the expression given in 4.7.2
11、, one obtains the formula V x 62.5 V. x m 8.2 Precision Comparative analyses, on samples of two washing powders containing respectively 10 % (m/m) of perborate about 2 % tmlml of B,O,l and 25 % (m/m) of perborate about 5.7 % (m/m) of Bz0-J carried out in eight laboratories, have given the statistica
12、l results given in the following table. Table 9 Test report The test report shall include the following information : a) all information necessary for the complete identification of the sample; bl the reference of the method used (reference to this In- ternational Standard); c) the results and the m
13、ethod of expression used; d) the test conditions; e) any details not specified in this International Standard or in the International Standards to which reference is made, or regarded as optional, as well as any incidents likely to have affected the results. 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 07:39:50 MDTNo reproduction or networking permitted without license from IHS -,-,-