S.L. 437.67 Art. 5water in a 200 trichloroacetic and filter central part of the cell. Cover solution Turn the cell Leave to hour at 40ºC. solution with sample to be analysed. 6. 1 ml of H 2 precentage of Repeatibility The the same 7. If the

Procedure

Weigh 10 g of sample to the nearest 1 mg and place with 100 ml of ml graduated flask. Mix in the tumbler for 30 minutes. Add 50 ml of acid solution (3.1), make upto volume with water, shake vigorously through a pleated filter. Using a pipette, introduce 1 ml of boric acid solution (3.3) into the the Conway cell and 1 ml of the sample filtrate into the crown of partially with the greased lid. Drop 1 ml of saturated potassium carbonate (3.4) quickly into the crown and close the lid so that the cell is airtight. carefully rotating it in a horizontal plane so that the two reagents are mixed. incubate either for at least four hours at room temperature or for one

Using a microburette (4.3), titrate the volatile bases in the boric acid sulphuric acid 0ꞏ02 N (3.5).

Carry out a blank test using the same procedure but without a

Calculation of results SO 0ꞏ02 N corresponds to 0ꞏ34 mg of ammonia. Express the result as a 4 the sample.

difference between the results of two parallel determinations carried out on sample should not exceed: 10%, in relative value, for ammonia contents of less than 1ꞏ0%; 0ꞏ1%, in absolute value, for ammonia contents of 1ꞏ0% or more.

Observation ammonia content of the sample exceeds 0ꞏ6%, dilute the initial filtrate. B. BY DISTILLATION