BS EN ISO 27587 pdf free download

BS EN ISO 27587-2021 pdf free download.Leather – Chemical tests – Determination of free formaldehyde in process auxiliaries.
5.7 CalibratIon standards. Prepare solutions by adequate dilution of the formaldchyde-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 Si, 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 Si (SJ..il) 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 (DNPI-I cartridges), suitable for fixing a total of 6 400 pg
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 (61).
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 um, 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.
7.2 Setting of initial conditions
Prepare a sample preparation system as described in II. Initially, the U-tube (&4) and the DNPI-I cartridge (5J.2) are disconnected from the sampling system. All the parts of the sample preparation system shall be dry prior to use. Add 3 g to 4 g of sea sand (68) to the U-tube (4), ensuring that it is not blocked and that the nitrogen flow can be maintained. Connect the U-tube and purge the system for 15 mm with nitrogen (3) at a flow rate of 500 mI/mm. It is important that the analysis be carried out under an inert atmosphere. The sampling system is slightly pressurized; therefore, all stopcocks should be secured with joint clamps.
7.3 Sample preparation
Accurately weigh 0,1 g to 2 g of sample to the nearest 0,001 g into the U-tube. It may be necessary to reduce the amount of sample if it is in a liquid phase to diminish the likelihood of condensed water giving erroneous results. The sample shall not be diluted. If the sample contains an amount of formaldehyde higher than 80% of the cartridge capacity, either reduce the sample, increase the number of cartridges to be loaded in series (see SJ.2) or do both. Apply a thin layer of stopcock grease (9) to the joints of the U-tube.
For each sample. restore the initial conditions (72).
In the case of a series of similar samples (different batches from the same production), the procedure of
purging with nitrogen may be reduced to 5 mm after the first sample.
7.4 Analysis
Introduce the DNPH cartridge (J2) place the U-tube into the oil bath (&1) preheated to (90 ± 3) °C and check the flow rate of nitrogen (350 mI/mm to 150 mI/mm). The U-tube and cartridge shall be covered with aluminium foil to protect them against heat loss.
The U-tube shall be immersed in the oil bath until Level A indicated in Figurel. During sampling, it may be necessary to readjust the flow rate. Check that the temperature is (90 ± 3) °C. After 30 mm, remove the U-tube containing the sample from the oil bath. Remove any condensate from the cartridge side of the tubing and stopcock using a hair dryer ([6.12). This step shall be carried out irrespective of whether condensate can be observed.BS EN ISO 27587 pdf download.