BS EN ISO 27587:2021 pdf download.Leather — Chemical tests — Determination of free formaldehyde in process auxiliaries.
5 Reagents
Use only reagents of recognized analytical grade, unless otherwise stated.
5.1 Sulfuric acid, 3 mol/l.
5.2 Sodium hydroxide, 2 mol/l.
5.3 Sodium thiosulfate, 0,1 mol/l.
5.4 Iodine solution, 0,05 mol/l, i.e. 12,68 g iodine per litre of water.
5.5 Starch solution, 1 g/100 ml water.
5.6 Formaldehyde-2,4-DNPH analytical standard.
5.7 Calibration standards. Prepare solutions by adequate dilution of the formaldehyde-2,4-DNPH
analytical standard (5.6).
5.8 Formaldehyde solution, a mass fraction of approximately 37 %.
5.9 Distilled water, quality 2 in accordance with ISO 3696.
5.10 Formaldehyde solution S1, prepare by pipetting 5 ml of formaldehyde solution (5.8) in a 1 000 ml volumetric flask and filling to the mark with distilled water.
5.11 Formaldehyde solution S2 in an adequate dilution for procedure control [e.g. 2,5 ml of
the formaldehyde solution S1 (5.10) in a 100 ml volumetric flask, fill up with distilled water. The
concentration of this solution should be adapted to ensure that the formaldehyde content is in the middle of the calibrated range.]
5.12 2,4-Dinitrophenylhydrazine cartridges (DNPH cartridges), suitable for fixing a total of 6 400 µg of carbonyls per cartridge.
For lower quantities of free formaldehyde, a smaller capacity cartridge can be used.
For higher quantities of free formaldehyde, increase the number of cartridges to be loaded in series.
It is recommended that the cartridge has an excess capacity of at least 20 % more than the predicted formaldehyde amount.
5.13 Acetonitrile, HPLC grade.
5.14 Water, HPLC grade.
6 Apparatus and materials
The usual laboratory apparatus is required and, in particular, the following.
6.1 Thermostatic oil bath with stirring facilities, capable of maintaining a constant temperature of
(90 ± 3) °C. The oil bath shall be deep enough to allow the U-tube to be dipped in up to the side tubing.
6.2 Silicone oil, suitable for oil bath (6.1).
6.3 Nitrogen, purity 4,6.
6.5 Flow meter, suitable to adjust a constant gas flow.
6.6 Silicone tubing.
6.7? Syringe? filters, e.g. 0,45 µm, regenerated cellulose.
6.8 Sea sand, purified by acid and calcined; quality grade GR for analysis.
6.9? Polytetrafluoroethylene? (PTFE)? stopcock? grease, free of formaldehyde.
6.10 HPLC equipped with a UV or DAD detector.
6.11 HPLC column, of the RP-C18 type.
6.12 Hair dryer.
6.13? Volumetric? flasks, 10 ml.
7 Methods
7.1 Outline of sample preparation system
See Figure 2.
14 Test report
The test report shall include the following:
a) a reference to this document (ISO 27587:2021);
b) the type, origin and designation of the analysed product and the sampling method used;
c) the analytical result for free formaldehyde content in milligrams per kilogram (mg/kg), rounded to one decimal place;
d) any deviation from the analytical procedure;
e) the date of the test.BS EN ISO 27587 pdf download.