71.080.30 - Organic nitrogen compounds
ICS 71.080.30 Details
Organic nitrogen compounds
Organische Stickstoffverbindungen
Composes organiques de l'azote
Organske dušikove spojine
General Information
This document specifies a spectrometric method of determining the colour, expressed in Hazen units, of a 50 % aqueous caprolactam solution as a measure of coloured impurities content of the sample.
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This document specifies a spectrometric method for the determination of the absorbance at a wavelength of 290 nm of caprolactam for industrial use.
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This International Standard specifies a spectrometric method for the determination of the permanganate absorption number of caprolactam for industrial use. The permanganate absorption number is a measure of the oxidizable impurities in caprolactam, determined in a buffered neutral aqueous medium under fixed conditions. The method is applicable to purified caprolactam (and intermediates in the caprolactam purification process) with an alkalinity or acidity lower than 0,50 mmol/kg and a PAN value of up to 35.
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The volatile bases are distilled in alkaline medium under specified conditions and collected in a known volume of a standard volumetric hydrochloric acid solution in the presence of an indicator. The excess of the acid is titrated with a standard volumetric sodium hydroxide solution.
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Equal volumes of potassium permanganate solution are added to a carpolactam test solution and to a blank (water). After standing for a specified time the absorbance, at a wavelength of 420 nm, of the test solution and of the blank are compared in cells of 5 cm thickness. The permanganat index is the difference between the absorbance of the test sample and that of the blank, multiplied by 100/3. It is a conventional measure of the content of oxidizable impurities.
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The absorbance of a 50 % aqueous caprolactam solution is spectrometrically measured at a wavelength of 390 nm and an optical path length of 50 mm. The result is expressed in Hazen units by multiplying the absorbance measured by a constant factor equal to 150. This factor is derived from measurements of absorbance of diluted standard solutions of platinum-cobalt scale.
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A sample of liquid caprolactam, or a liquefied sample of crystalline caprolactam is cooled and the temperature at which crystallization occurs is observed.
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The spectrometric measurement of the absorbance of a 50 % caprolactam water solution is carried out at a wavelength of 290 nm. The absorbance, expressed in relation to an optical path length of 1 m, is given by a specified formula in which AO is the correction for the difference in absorbances of the cells; A1 is the absorbance of the test solution, and 1 is the optical path length, in centimetres, of the cell.
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The procedure is based on the catalytic conversion of nitrogen present in a test portion to ammonia by heating in concentrated sulphuric acid solution. Distillation and absorption of the ammonia in an excess of standard volumetric sulphuric acid solution and back-titration with standard volumetric sodium hydroxide solution in the presence of an indicator. - Replaces ISO Recommendation R 1592-1970.
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The principle consists in titration of the alkalinity of a test portion with a standard volumetric hydrochloric acid solution in the presence of an indicator. - Replaces ISO Recommendation R 1593-1970.
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The procedure consists in the ignition of a test portion in a platinum dish at (800 25) °C to constant mass. - Replaces ISO Recommendation R 1594-1970.
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Applicable to products having contents of equal to or more than 0.05 % (m/m) (with flame atomic absorption) or 0.1 % (m/m) (with fotometric absorption). Covers the formation of a complex between biuret and copper(II) sulphate in alkaline medium. Fixation of this complex on an anion exchange resin. Elution of Cu first with a potassium nitrate solution and then with a nitric acid solution. Flame atomic absorption: aspiration of the solution into an acetylene-air flame and measurement of the absorption of the 325-nm line emitted by a copper hollow-cathode lamp; or by photometric absorption: formation of a coloured complex between Cu and zinc dibenzyldithiocarbamate, extraction with carbon tetrachloride and measurement at a wavelength of about 435 nm. Has also been approved by the IUPAC.
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Lays down the principle of the visual comparison of the colour of a solution of the sample in formaldehyde, stabilized at a pH of 10 0.1, with that of colour standards. Expression of the results in terms of Hazen units. For routine control purposes, referring to ISO 2211. The method has also been approved by the IUPAC.
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Applicable to the determination in the presence of ammoniacal salts less than 15 mg in the aliquot amount taken for the determination. In the presence of quantities exceeding 15 mg the ammoniacal nitrogen shall be removed by a cation exchange resin because these salts interfere with the determination. The principle of the reaction consists in formation of a violet-red complex between allophanic acid amide (H2 N.CO.NH.CO.NH2 ) and copper sulphate in the presence of an alkaline solution of potassium sodium tartrate. Photometric measurement at a wavelength of about 550 nm. Has also been approved by the IUPAC.
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Specifies the manner in which this method is to be applied in a reaction of any water present in urea with a solution of iodine and sulphur dioxide in a mixture of pyridine and methanol (Karl Fischer reagent). This reagent is first standadized by titration with a precisely known mass of water. The end point of the reaction is read by the direct visual or direct electrometric method. The method has also been approved by the IUPAC.
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Specifies the principle of measurement, at (20 0.5) 0C, of the quantity of 0.01 N sodium hydroxide standard volumetric solution required to take the pH of a solution containing 50 g of sample in 100 ml of water to a pH of 8.3 after addition of formaldehyde. Has also been approved by the IUPAC.
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Applicable to solutions of conventional concentration. The principle consists in measurement, at (20 0.5) 0C, of the quantity of 0.05 N acid solution required to effect a pH change from 8 to 6 for a solution containing 100 g of urea in 1000 ml of solution. For the measurement a pH meter is used fitted with a glass electrode and a calomel electrode. The method has also been approved by the IUPAC.
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Describes the measurement of a solution of a test sample by means of a pH meter fitted with one glass electrode and one calomel electrode. The pH meter has a sensitivity of 0.05 pH units. The calibration of the pH meter is carried out at (20 0.5) 0C by means of buffer solutions. The method has also been approved by the IUPAC.
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Describes a method applicable to iron contents greater than or equal to 0.00005 % (m/m). The principle is based on the ignition of the material at 800 °C and fusion of the residue with anhydrous potassium hydrogen sulphate. Solution of the cooled melt in hydrochloric acid and reduction of iron(III) by means of hydroxylammonium chloride. Formation of an iron(II)-2,2'bipyridyl complex in the presence of a buffered solution (pH value between 4.5 and 6). Photometric measurement of the coloured complex at a wavelength of about 522 nm.
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