BBG Analyt.Method Phophor
This method of analysis specifies a quinoline phosphomolybdate gravimetric method for the determination of the total phosphorus content of feed phosphates (based on Directive 77/535/CEE method 3.2).

Principle
Solubilisation and hydrolysis of a test portion by boiling with mineral acid. Precipitation of phosphoric acid in the form of quinoline phosphomolybdate, in the presence of acetone. Filtration, washing, drying and weighing of the precipitate.

Apparatus
Usual laboratory equipment and in particular:
Filter crucible of sintered glass, porosity P10 or P16 (pore size index from 4 to 16 µm).
Oven, capable of being controlled at 250°C?10°C.
Flameless heating apparatus.

Reagents
During the analysis, use only reagents of recognised analytical reagent grade and only distilled water of equivalent quality.
Hydrochloric acid (HCl); p = 1.13g/ml, about 26 %(m/m)
Nitric acid (HNO3); p = 1.20g/ml, about 32 %(m/m)
Citromolybdate or quimociac reagent
1) Dissolve 70g of sodium molybdate dihydrate (Na2MoO4.2H20) in 150ml of water.
2) Dissolve 60g of citric acid monohydrate (C6H807.H20) in 150ml of water and add 85ml of nitric acid (HNO3) solution, approximately 1.38g/ml, about 63 % (m/m)
3) Pour, while stirring, solution 1 into solution 2
4) Add 25ml of nitric acid (HNO3) solution, approximately 1.38g/ml, about 63% (m/m), then 5ml of recently distilled quinoline (C6H4NC3H3) to 100ml of water.
5) Pour solution 4 into solution 3 and mix. Allow to stand for 12 hours and filter through the filter crucible (3.1). Store this solution in a well stoppered flask of, for example, polyethylene.
6) Add 280ml of acetone ((CH3)2CO) to solution 5 and dilute to 1000mi with water. Store under the same conditions as solution 5.
Monopotassium dihydrogen orthophosphate (KH2PO4) to dried constant mass at 100°C.

Procedure
Test portion and preparation of test solution. Grind at least 100g of the material until it passes a 500µm sieve (size ISO 565).
1) Materials in which the absence of water insolubles and polyphosphates has not been verified: Weigh to the nearest 0.0002g. 2.5g of the test portion in such a way that there is no gain or loss of moisture. Transfer the test portion to a flask of about 250ml capacity, add 150ml of water, 10ml of hydrochloric acid (4.1) and 40ml of nitric acid (4.2), then boil for 30 minutes. Cool, transfer the solution quantitatively to a 500ml one mark volumetric flask, dilute to the mark and filter.
2) Materials in which the absence of water insolubles has been verified, but which contain polyphosphates: Place the test portion in the flask, add l5ml of hydrochloric acid (4.1) and boil for about 20 minutes. Cool and add about 100ml of water. Fit a reflux condensor and boil for one hour. Cool and prepare the solution as described above.
Determination
Depending on the expected phosphorus content, transfer to a 400ml beaker the aliquot part of the test solution (5.1) containing 6.5-11mg P with a maximum of l5mg P and shown in the following table:

Expected P content % (m/m) Aliquot part of test solution 5.1 to be taken (ml)
6.5-11.0 20
11.0-22.0 10
> 22.0 5

Dilute to about 100ml and add 50ml of the citromolybdate reagent (4.3). Cover the beaker with a clock glass and warm its contents on a hot plate at 75°C?5°C for about 30 seconds (do not use a flame and do not mix during the addition of the reagent or while heating, in order to prevent the formation of clots). Allow to cool to ambient temperature, stirring three or four times with a glass rod.
Place the filter crucible in the oven at 250°C?10°C and leave for l5 minutes counted from the moment when this temperature has been re-established. Allow to cool in a dessicator and weigh to the nearest 0.0001g.
Decant the liquid through the filter crucible and wash the precipitate six times by decantation, using about 30ml of water each time. Transfer the rest of the precipitate to the filter crucible by means of a jet of water from a wash bottle. Then wash the precipitate four times, removing each portion of wash water by means of a vacuum pump.
Place the filter crucible in the oven at 250°C?10°C and heat to constant mass. Normally 15 minutes, counted from the moment when this temperature is re-established, is sufficient. Allow to cool to ambient temperature in a dessicator and weigh to the nearest 0.0001g.

Blank test
Carry out a blank test, in parallel with the determination and following the same procedure, using the same quantities of all the reagents as those used for the determination.

Check-test
Carry out the determination on an aliquot portion, containing 6.54mg of P, of monopotassium dihydrogen orthophosphate solution: Weigh 2.8742g of the mono potassium dihydrogen orthophosphate into a 1000ml one mark volumetric flask. Dissolve in water and dilute to the mark. Use as the test-portion 10ml of this solution, equivalent to 6.54mg of P, and use the same conditions, reagents and blank-test.

Expression of results
The total phosphorus (P) content, in % (m/m), is given by the formulae:

P = (m1 - m2) x f x 100 = (m1 - m2) 0.2800
2,500 x D D
50O

where:
m1 is the mass, in grams, of the precipitate obtained with the aliquot part of the test solution (5.2),
m2 is the mass, in grams, of the precipitate obtained with the corresponding aliquot part of the blank test solution (5.3)
D is the volume of test solution 5.1 in ml
f is 0.013998 for conversion of quinoline phosphomolybdate to phosphorus (P).

G Analyt.Method Phophorus

Phosphorus
Scope and field of application
This method of analysis specifies a quinoline phosphomolybdate gravimetric method for the determination of the total phosphorus content of feed phosphates (based on Directive 77/535/CEE method 3.2).

Principle
Solubilisation and hydrolysis of a test portion by boiling with mineral acid. Precipitation of phosphoric acid in the form of quinoline phosphomolybdate, in the presence of acetone. Filtration, washing, drying and weighing of the precipitate.

Apparatus
Usual laboratory equipment and in particular:
Filter crucible of sintered glass, porosity P10 or P16 (pore size index from 4 to 16 µm).
Oven, capable of being controlled at 250°C?10°C.
Flameless heating apparatus.

Reagents
During the analysis, use only reagents of recognised analytical reagent grade and only distilled water of equivalent quality.
Hydrochloric acid (HCl); p = 1.13g/ml, about 26% (m/m)
Nitric acid (HNO3); p = 1.20g/ml, about 32% (m/m)
Citromolybdate or quimociac reagent
1) Dissolve 70g of sodium molybdate dihydrate (Na2MoO4.2H20) in 150ml of water.
2) Dissolve 60g of citric acid monohydrate (C6H807.H20) in 150ml of water and add 85ml of nitric acid (HNO3) solution, approximately 1.38g/ml, about 63% (m/m)
3) Pour, while stirring, solution 1 into solution 2
4) Add 25ml of nitric acid (HNO3) solution, approximately 1.38g/ml, about 63% (m/m), then 5ml of recently distilled quinoline (C6H4NC3H3) to 100ml of water.
5) Pour solution 4 into solution 3 and mix. Allow to stand for 12 hours and filter through the filter crucible (3.1). Store this solution in a well stoppered flask of, for example, polyethylene.
6) Add 280ml of acetone ((CH3)2CO) to solution 5 and dilute to 1000mi with water. Store under the same conditions as solution 5.
Monopotassium dihydrogen orthophosphate (KH2PO4) to dried constant mass at 100°C.

Procedure
Test portion and preparation of test solution. Grind at least 100g of the material until it passes a 500µm sieve (size ISO 565).
1) Materials in which the absence of water insolubles and polyphosphates has not been verified: Weigh to the nearest 0.0002g. 2.5g of the test portion in such a way that there is no gain or loss of moisture. Transfer the test portion to a flask of about 250ml capacity, add 150ml of water, 10ml of hydrochloric acid (4.1) and 40ml of nitric acid (4.2), then boil for 30 minutes. Cool, transfer the solution quantitatively to a 500ml one mark volumetric flask, dilute to the mark and filter.
2) Materials in which the absence of water insolubles has been verified, but which contain polyphosphates: Place the test portion in the flask, add l5ml of hydrochloric acid (4.1) and boil for about 20 minutes. Cool and add about 100ml of water. Fit a reflux condensor and boil for one hour. Cool and prepare the solution as described above.
Determination
Depending on the expected phosphorus content, transfer to a 400ml beaker the aliquot part of the test solution (5.1) containing 6.5-11mg P with a maximum of l5mg P and shown in the following table:

Expected P content % (m/m) Aliquot part of test solution 5.1 to be taken (ml)
6.5-11.0 20
11.0-22.0 10
> 22.0 5

Dilute to about 100ml and add 50ml of the citromolybdate reagent (4.3). Cover the beaker with a clock glass and warm its contents on a hot plate at 75°C?5°C for about 30 seconds (do not use a flame and do not mix during the addition of the reagent or while heating, in order to prevent the formation of clots). Allow to cool to ambient temperature, stirring three or four times with a glass rod.
Place the filter crucible in the oven at 250°C?10°C and leave for l5 minutes counted from the moment when this temperature has been re-established. Allow to cool in a dessicator and weigh to the nearest 0.0001g.
Decant the liquid through the filter crucible and wash the precipitate six times by decantation, using about 30ml of water each time. Transfer the rest of the precipitate to the filter crucible by means of a jet of water from a wash bottle. Then wash the precipitate four times, removing each portion of wash water by means of a vacuum pump.
Place the filter crucible in the oven at 250°C?10°C and heat to constant mass. Normally 15 minutes, counted from the moment when this temperature is re-established, is sufficient. Allow to cool to ambient temperature in a dessicator and weigh to the nearest 0.0001g.

Blank test
Carry out a blank test, in parallel with the determination and following the same procedure, using the same quantities of all the reagents as those used for the determination.

Check-test
Carry out the determination on an aliquot portion, containing 6.54mg of P, of monopotassium dihydrogen orthophosphate solution: Weigh 2.8742g of the mono potassium dihydrogen orthophosphate into a 1000ml one mark volumetric flask. Dissolve in water and dilute to the mark. Use as the test-portion 10ml of this solution, equivalent to 6.54mg of P, and use the same conditions, reagents and blank-test.

Expression of results
The total phosphorus (P) content, in % (m/m), is given by the formulae:

P = (m1 - m2) x f x 100 = (m1 - m2) 0.2800
2,500 x D D
500

where:
m1 is the mass, in grams, of the precipitate obtained with the aliquot part of the test solution (5.2),
m2 is the mass, in grams, of the precipitate obtained with the corresponding aliquot part of the blank test solution (5.3)
D is the volume of test solution 5.1 in ml
f is 0.013998 for conversion of quinoline phosphomolybdate to phosphorus (P).

Scope and field of application
This method of analysis specifies a quinoline phosphomolybdate gravimetric method for the determination of the total Phosphorus content of feed phosphates (based on Directive 77/535/CEE method 3.2).

Principle
Solubilisation and hydrolysis of a test portion by boiling with mineral acid. Precipitation of phosphoric acid in the form of quinoline phosphomolybdate, in the presence of acetone. Filtration, washing, drying and weighing of the precipitate.

Apparatus
Usual laboratory equipment and in particular:
Filter crucible of sintered glass, porosity P10 or P16 (pore size index from 4 to 16 µm).
Oven, capable of being controlled at 250°C?10°C.
Flameless heating apparatus.

Reagents
During the analysis, use only reagents of recognised analytical reagent grade and only distilled water of equivalent quality.
Hydrochloric acid (HCl); p = 1.13g/ml, about 26% (m/m)
Nitric acid (HNO3); p = 1.20g/ml, about 32% (m/m)
Citromolybdate or quimociac reagent
1) Dissolve 70g of sodium molybdate dihydrate (Na2MoO4.2H20) in 150ml of water.
2) Dissolve 60g of citric acid monohydrate (C6H807.H20) in 150ml of water and add 85ml of nitric acid (HNO3) solution, approximately 1.38g/ml, about 63% (m/m)
3) Pour, while stirring, solution 1 into solution 2
4) Add 25ml of nitric acid (HNO3) solution, approximately 1.38g/ml, about 63% (m/m), then 5ml of recently distilled quinoline (C6H4NC3H3) to 100ml of water.
5) Pour solution 4 into solution 3 and mix. Allow to stand for 12 hours and filter through the filter crucible (3.1). Store this solution in a well stoppered flask of, for example, polyethylene.
6) Add 280ml of acetone ((CH3)2CO) to solution 5 and dilute to 1000mi with water. Store under the same conditions as solution 5.
Monopotassium dihydrogen orthophosphate (KH2PO4) to dried constant mass at 100°C.