BS EN 14397-1:2010 pdf download.Fertilizers and liming materials – Determination of carbon dioxide Part 1: Method for solid fertilizers.
This document specifies a method for the determination of carbon dioxide in solid fertilizers.
The method applies to all fertilizers that contain carbonates and/or bicarbonates.
NOTE If the fertilizer contains any other substances that release carbon dioxide on treatment with phosphoric acid.
this will also be determined and expressed as carbon dioxide.
2 Normative references
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 ISO 3696:1995, Water for analytical Iaboratoty use — Specification and test methods (ISO 3696:1987)
3 Principle
The carbon dioxide is liberated by treatment with phosphoric acid and absorbed in a solution of barium hydroxide. Barium carbonate precipitates and the excess barium hydroxide is back-titrated with hydrochloric acid.
4 Reagents
Use only reagents of recognized analytical grade.
4.1 Water, conforming to EN ISO 3696:1995, grade 3.
Boil the water immediately before use, to drive off any dissolved carbon dioxide.
4.2 Nitrogen, with a low content of carbon dioxide and organic Impurities.
4.3 Hydrochloric acid, standard volumetric solution, c(HCI) = 0,1 molfl.
4.4 BarIum hydroxide, standard volumetric solution, (Ba(OH)2) = 0,05 mot!l approximately.
Standardize the barium hydroxide solution by titrating against the hydrochloric acid solution (4.3), using the phenolphthalein solution (4.6) as indicator.
5 Apparatus
Usual laboratory apparatus and the fllowing are required.
5.1 Analytical balance, capable of weighing to an accuracy of 0,1 mg.
5.2 Laboratory grinder or mortar and pestle.
5.3 Burette, for barium hydroxide solution (see Figure 1).
5.4 Glassware assembly, as shown in Figure 2, comprising the following:
a) flow meter for nitrogen (1);
b) pressure relief tube with 850 mm water column (2);
c) washing flasks with 250 ml capacity, fleld with soda lime pellets and indicator (3);
d) 500 ml reservoir for phosphoric acid with rubber ball used as acid dosing unit (4);
e) round-bottom, three-necked reaction flask ftted with a splash head (5);
f) three absorption vessels, each of 250 ml capacity, with fitted glass tubes to ensure full absorption of the liberated carbon dioxide (7), (8), (9).
The frit in the first vessel (7) should be coarse enough to avoid blockage during the absorption. Alternatively,the frit may be replaced by a mushroom bubbler with small holes.
5.5 WeighIng boat.
5.6 Hot plate, see (6) in Figure 2.
6 Sampling and sample preparation
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. Prepare the sample to obtain a laboratory sample of at least 100 g. Grind the laboratory sample to give a test sample with a particle size of less than 200 lam and mix thoroughly.
7 Procedure
SAFETY PRECAUTIONS — Appropriate precautions should be taken to avoid harmful compounds, which can be given off during the phosphoric acid treatment, from getting into the laboratory atmosphere.
7.1 Test portion
Weigh in the weighing boat (5.5). to the nearest 0,1 mg, an amount of the test sample containing not more than 40 mg of carbon dioxide. As a guide. the test portion should be no more than 200 mg for calcium ammonium nitrate (CAN) and 90 mg for dolomite.
7.2 Determination
Carefully assemble the apparatus shown in Figure 2 ensuring there are no leaks. Purge the entire apparatus with nitrogen (4.2) for 30 mm. Disconnect the three absorption vessels in the order (9), (8) and (7) whilst maintaining the nitrogen stream. Pipette into each vessel 50 ml of the barium hydroxide solution (4.4). Reconnect the vessels to the apparatus and purge for a further 5 mm. Disconnect the bulb and flexible tube and add 20 ml of phosphoric acid solution (4.5) to the acid-dosing unit (4).
Introduce the test portion (7.1)10 the round bottom three-necked reaction flask (5) through the stopper. Rinse the weighing boat and the neck of the stopper into the flask using 20 ml to 25 ml of water.
Reduce the nitrogen flow to five litre per hour. Create an overpressure in the reservoir with the rubber ball so that by opening the valve of the acid-dosing unit (4) the phosphoric acid passes to the round bottom reaction flask (5).
Start the magnetic stirrer and heat the contents of the round bottom reaction flask (5) by means of the hot plate (5.6) to boiling and boil gently for 2 h. Ensure that the temperature in the flask does not exceed 100 °C. Discontinue heating and disconnect the absorption vessels in the order (9). (8) and (7). Rinse the absorption vessels from above with water.
Slowly back-titrate the excess barium hydroxide in each absorption vessel with the hydrochloric acid (4.3) using the phenolphthalemn solution (4.6) as indicator. Carry out the titration under nitrogen, to prevent absorption of carbon dioxide from the atmosphere.
NOTE Local excesses of hydrochloric acid should be avoided as these can dissolve some of the precipitated banum carbonate. Magnetic stirring during the titration helps to minimize the local excess of acid.
If the equivalent of more than 1 ml of barium hydroxide solution in absorption vessel (9) has been consumed by reaction with carbon dioxide, repeat the determination with a reduced flow of nitrogen.
7.3 Blank test
Carry out a blank test by the procedure described in 7.2 but omitting the test portion (7.1).BS EN 14397-1 pdf free download.