BS ISO 19670:2017 pdf free
BS ISO 19670:2017 pdf free.Fertilizers and soil conditioners一Solid urea aldehyde slow release fertilizer
Place an accurately weighed test portion containing 0,12 g CWIN (accurate to 0,000 1 g) in a 250 ml tall-form beaker. Add 100 ml 100 °C phosphate buffer solution (5.4.2.1) from a graduated cylinder to the test portion, stir, cover and immerse promptly in a boiling water bath (5.5.3.2) so that liquid in the beaker is below the water level in the water bath. Maintain the water bath at 98 °C to 100 °C, check with a thermometer and stir at 10 min intervals. After exactly 30 min, remove the beaker from the water bath and filter promptly through a piece of filter paper (5.4.3.3). If filtration takes more than 4 min, discard determination. Repeat the determination, adding 1 g celite (5.5.2.2) as filter-aid just before removing the beaker from the water bath, stir and filter.
Wash the insoluble residue completely onto the filter paper with boiling water and continue washing until the total volume used is 100 ml. Complete washing before the filtrate becomes cloudy or its temperature drops to below 60 °C. Determine total nitrogen in the wet filter paper and residue in accordance with ISO 5315.
Carry out a blank test at the same time as the determination, using the same procedure and reagents,but omitting the test protion.
Mix all the increments (collected as in 6.1) uniformly and promptly to form a single aggregate sample using a device or by hand. The aggregate sample is reduced to about 1 kg according to the procedure in ISO 7742. Next, divide into two parts for final laboratory samples. The two laboratory samples are put into two clean and dry glass or plastic containers or any other inert material of adequate resistance capable of maintaining the sample in its original condition. The containers shall be fitted with airtight closures. Carry out all the operations described above as rapidly as possible to avoid loss or gain of moisture. Each container shall be secured and sealed following the instruction given in ISO 7410. Each laboratory sample shall be labelled following the instructions given in ISO 7410.BS ISO 19670 pdf download.
