Paragraph 8 EXPRESSION OF RESULT
Express the result of the analysis as the percentage of ammoniacal nitrogen in the fertiliser as received for analysis using the formula
where
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50 (or 35 where variant (c) applies) = millilitres of standard solution of sulfuric acid in the receiving flask.
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A = m illilitres of sodium or potassium hydroxide used for the titration.
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F = factor taking into account the weight of sample, the dilution, the volume of the aliquot portion distilled and the volumetric equivalent.
TABLE FOR METHOD 2
Determination of the ammoniacal nitrogen and of the ammoniacal and nitrate nitrogen in fertilisers. Table of the weighing, dilution and calculation to be carried out for each of the variants (a), (b) and (c) of the method.Variant (a) —Approximate maximum quantity of nitrogen to be distilled = 50 mgSulfuric acid 0.05 M to be placed in the receiving flask = 50 mlTitration with sodium or potassium hydroxide, 0.1 M solution
| Declaration N% | Amount to be weighed (g) | (Volume) Dilution (ml) | Volume of sample solution to be distilled (ml) | Factor F |
|---|---|---|---|---|
| 0-5 | 10 | 500 | 50 | 0.14 |
| 5-10 | 10 | 500 | 25 | 0.28 |
| 10-15 | 7 | 500 | 25 | 0.40 |
| 15-20 | 5 | 500 | 25 | 0.56 |
| 20-40 | 7 | 500 | 10 | 1.00 |
Variant (b) —Approximate maximum quantity of nitrogen to be distilled = 100 mgSulfuric acid 0.1 M to be placed in the receiving flask = 50 mlTitration with sodium or potassium hydroxide, 0.2 M solution
| Declaration N% | Amount to be weighed (g) | (Volume) Dilution (ml) | Volume of sample solution to be distilled (ml) | Factor F |
|---|---|---|---|---|
| 0-5 | 10 | 500 | 100 | 0.14 |
| 5-10 | 10 | 500 | 50 | 0.28 |
| 10-15 | 7 | 500 | 50 | 0.40 |
| 15-20 | 5 | 500 | 50 | 0.56 |
| 20-40 | 7 | 500 | 50 | 1.00 |
Variant (c) —Approximate maximum quantity of nitrogen to be distilled = 200 mgSulfuric acid 0.25 M to be placed in the receiving flask = 35 mlTitration with sodium or potassium hydroxide, 0.5 M solution
| Declaration N% | Amount to be weighed (g) | (Volume) Dilution (ml) | Volume of sample solution to be distilled (ml) | Factor F |
|---|---|---|---|---|
| 0-5 | 10 | 500 | 200 | 0.175 |
| 5-10 | 10 | 500 | 100 | 0.350 |
| 10-15 | 7 | 500 | 100 | 0.500 |
| 15-20 | 5 | 500 | 100 | 0.700 |
| 20-40 | 5 | 500 | 50 | 1.400 |