BS EN 15920-2011 pdf download.Fertilizers Extraction of phosphorus soluble in 2% citric acid.
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1482-2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample preparation
EN 12944-1:1999. Fertilizers and liming materials and soil improvers — Vocabulary — Part 1: General terms
EN 12944-2:1999, Fertilizers and liming materials and soil improvers — Vocabulary — Part 2: Terms relating to fertilizers
CEN/TS 15959, Fertilizers — Determination of extracted phosphorus
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12944-1:1999 and EN 12944-2:1999 apply.
4 Sampling
Sampling is not part of the method specified in this document. A recommended sampling method is given in
EN 1482-1,
Sample preparation shall be carried out In accordance with EN 1482-2. Grinding is recommended for homogeneity reasons.
5 Principle
Extraction of phosphorus from the sample with a 2 % citric acid solution (20 g/l) under specified conditions,
6 Reagents
6.1 Water. distilled or demineralized.
6.2 2 % citric acid solution, , = 20 gIl, prepared from crystallized citric acid (C6H807 H20).
Verify the mass concentration of the citric acid solution by titrating 10 ml of the latter with a sodium hydroxide standard solution, c = 0,1 mol/l, using phenolphthalein as indicator.
If the solution is correct, 28,55 ml of the standard solution should be used.
7 Apparatus
7.1 Common laboratory equipment and glassware.
7.2 600 ml flask, with sufficiently wide neck allowing the liquid to be shaken thoroughly.
7.3 Rotary shaker, 35 rlmin to 40 rfmin.
7.4 Dry pleated filter, free from phosphates.
8 Procedure
8.1 Test portion
Weigh, to the nearest 0.001 g, 5 g of the prepared sample and place it in a dry 600 ml flask (7.2).
8.2 Extraction
Add to the test portion (500 ± 1) ml of the citric acid solution (6.2) at (20 ± 1) °C. When adding the first millilitres of the solution, shake vigorously by hand to avoid the formation of lumps and to prevent the substance sticking to the sides. Close the flask with a rubber stopper and shake it in the rotary shaker (7.3) for exactly 30 mm at a temperature of (20 ± 2) C.
Filter the solution Immediately through a dry pleated filter (7.4), Into a dry glass receiver (7.1) and discard the first 20 ml of the filtrate. Continue the filtering until a sufficient quantity of filtrate is obtained to carry out the phosphorus determination according to CENITS 15959.BS EN 15920-2011 pdf download.