BS EN ISO 27587:2021 pdf free.Leather -Chemical tests – Determination offree formaldehyde in process auxiliaries.
BS EN ISO 27587 Prepare a sample preparation system as described in 7.1. Initially, the U-tube (6.4) and the DNPHcartridge (5.12) are disconnected from the sampling system. All the parts of the sample preparationsystem shall be dry prior to use.Add 3 g to 4 g of sea sand (6.8) to the U-tube (6.4), ensuring that it isnot blocked and that the nitrogen flow can be maintained.Connect the U-tube and purge the system for15 min with nitrogen (6.3) at a flow rate of 500 ml/min. lt is important that the analysis be carried outunder an inert atmosphere.The sampling system is slightly pressurized; therefore, all stopcocks shouldbe secured with joint clamps.Accurately weigh 0,1 g to 2 g of sample to the nearest 0,001 g into the U-tube. It may be necessary toreduce the amount of sample ifitis in a liquid phase to diminish the likelihood of condensed water givingerroneous results. The sample shall not be diluted. If the sample contains an amount of formaldehydehigher than 80 % of the cartridge capacity, either reduce the sample, increase the number of cartridgesto be loaded in series (see 5.12)or do both.Apply a thin layer of stopcock grease (6.9) to the joints ofthe U-tube.For each sample, restore the initial conditions (7.2).
In the case of a series of similar samples (different batches from the same production), the procedure ofpurging with nitrogen may be reduced to 5 min after the first sample.
Introduce the DNPH cartridge (5.12), place the U-tube into the oil bath(6.1) preheated to (90±3)°Candcheck the flow rate of nitrogen (350 ml/min to 150 ml/min).The U-tube and cartridge shall be coveredwith aluminium foil to protect them against heat loss.The U-tube shall be immersed in the oil bath until level A indicated in Figure 1. During sampling, it maybe necessary to readjust the flow rate.Check that the temperature is (90 ± 3) °C.After 30 min, removethe 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 whethercondensate can be observed.BS EN ISO 27587 pdf download.