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BS ISO 18643:2016 pdf free

BS ISO 18643:2016 pdf free.Fertilizers and soil conditioners一Determination of biuret content of urea-based fertilizers一HPLC method
For urea fertilizers, simply take 500 g of divided sample as the test portion; for compound fertilizers,take a reduced laboratory sample of 100 g, and grind until it passes through a sieve of aperture size 0,5mm. Mix thoroughly to homogenize the sample. Place in a clean dry bottle with lid.
Duplicate replicate experiments shall be done for the final determination of result.Weigh 0,1 g ~ 0,5 g test sample (accurately to 0,000 2 g, with biuret content of 1 mg ~ 2 mg ca.) into a 25 ml beaker. Add 10 ml mobile phase (4.2) and dissolve using an ultrasonic bath for 10 min. Transfer to a 25 ml volumetric flask and dilute to volume with mobile phase (4.2). Mix thoroughly and leave standing. Filter with a syringe filer to obtain the test solution.
According to Table 1, pipette 0,00 ml, 0,50 ml, 1,00 ml, 3,00 ml, 5,00 ml and 10,00 ml biuret stock solution (4.3) into six separate 25 ml volumetric flasks. Dilute with respective volumes of mobile phase (4.2) and make up to the mark and mix thoroughly. Filter with 0,22 μm organic filter membrane.
Ensure that the HPLC apparatus operating conditions are optimized. Successively inject 10 μl working standard solution (6.3) and determine the series of biuret working standard solution. Each working standard solution shall be determined two times. Draw the standard curve or get the linear regression equation by calculating the average peak areas of the biuret and the corresponding mass.
Determine the test solution (6.2) with the same method of the working standard solution, measure the peak area, and calculate the biuret mass in each test solution according to the standard curve or linear regression equation. After completing the determination, first wash the system with mobile phase (4.2) for 30 min, then wash the system with absolute acetonitrile (4.1) for 30 min. Finally, turn off the apparatus according to the operating procedures.BS ISO 18643 pdf free download.

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