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The method is applicable to products having aldehyde contents in the range 0.00025 % (m/m) to 0.00125 % (m/m). The principle is based on the reaction of the aldehydes present in a test portion with Schiff reagent. Visual comparison of the colour obtained with the colours of standard colorimetric solutions containing known quantities of acetaldehyde. - International Standards ISO 1388/1 to ISO…

Provides rules for the presentation and the position of the contents list of periodicals (see also ISO 8). Cancels and replaces ISO Recommendation R 18-1956, of which it constitutes a technical revision.

Specifies a conventional gravimetric method for the determination. A test portion ist reated with quinoline in a beaker at 70 to 80 °C for 15 to 20 min. Then the dissolved test portion and the residue are brought to a Hartley funnel fitted with a filter pad, and are filtered. The washed and dried residue on the filter pad is weighed.

Specifies a method based on the depolymerization of any polymerized silica by treatment with sodium fluoride in the presence of hydrochloride acid resulting in the formation of the oxidized molycdosilicate, followed by the selective reduction of this complex in the presence of oxalic acid and in a sulphuric acid medium, and spectrophotometric measurement of the blue-coloured complex at the…

The principle is based on the conversion of methanol present in a test portion to formaldehyde by oxidation. The oxidation is carried out with a solution of potassium permanganate in phosphoric acid. Reaction of the formaldehyde formed with chromotropic acid (4,5-dihydroxynaphthalene-2,7-disulphonic acid). Photometric measurement of the violet coloration obtained at a wavelength of about 570 nm…

The principle is based on the conversion of the methanol present in a test portion to formaldehyde by oxidation with a solution of potassium permanganate in phosphoric acid. Reaction of the formaldehyde formed with Schiff reagent. Visual comparison of the colour obtained with the colours of standard colorimetric solutions containing known quantities of formaldehyde. - International Standards ISO…

The principle is based on distillation of a test portion in the presence of water, addition to the distillate of a saturated sodium chloride solution and measurement of the volume of insoluble hydrocarbons. A Hempel fractionating column with Liebig condenser is used for the distillation. - International Standards ISO 1388/1 to ISO 1377/12 cancel and replace ISO Recommendation R 1388-1970 of which…

The document also specifies the methods to be used for the determination of density at 20 °C, for the determination of dry residue after evaporation on a water bath, for the determination of water content, and for the measurement of colour. - International Standards ISO 1388/1 to 1388/12 cancel and replace ISO Recommendation R 1388-1970 of which they constitute a technical revision.

This second edition cancels and replaces the first edition (i.e. ISO 621-1975). Specifies principle, reagents, apparatus, sample, procedure and expression of results.