Delete the following:
Primary amines and ammonia
Disolve 200 mg in 10 mL of water, add 1 mL of acetone and 0.5 mL of freshly prepared sodium nitroferricyanide solution (1 in 10), mix, and allow to stand for 10 minutes, accurately timed. Determine the absorbance of this solution at 520 nm and at 600 nm, using a reagent blank as the reference solution. The ratio
A600/
A520 is not more than 0.5 (equivalent to about 0.7% of primary amines and ammonia).
USP32
Add the following:
Chromatographic purity
Solvent
Prepare a mixture of 13.5 N ammonium hydroxide and dehydrated alcohol (3:2).
Standard solution 1
Prepare a solution of USP Piperazine RS in Solvent containing 10 mg per mL.
Standard solution 2
Prepare a solution of ethylenediamine in Solvent containing 0.25 mg per mL.
Standard solution 3
Prepare a solution of triethylenediamine in Solvent containing 0.25 mg per mL.
Resolution solution
Prepare a solution in Solvent containing 0.25 mg of triethylenediamine and 10 mg of USP Piperazine RS per mL.
Test solution 1
Prepare a solution of Piperazine in Solvent containing 100 mg per mL.
Test solution 2
Mix 1 mL of Test solution 1 and 9 mL of Solvent.
Procedure
Apply separate 5-µL portions of
Standard solution 1, Standard solution 2, Standard solution 3, Resolution solution, Test solution 1, and
Test solution 2 to a suitable thin-layer chromatographic plate (see
Chromatography
621
), coated with a 0.25-mm layer of chromatographic silica gel. Allow the spots to dry, and develop the chromatograms in a solvent system consisting of a freshly prepared mixture of acetone and 13.5 N ammonium hydroxide (80:20) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and dry the plate at 105

. Spray the plate with a 0.3% (w/v) solution of ninhydrin in a mixture of butyl alcohol and glacial acetic acid (100:3). Spray the plate again with a 0.15% (w/v) solution of ninhydrin in dehydrated alcohol, dry the plate at 105

for 10 minutes, and examine the plate: any secondary spot in the chromatogram obtained from
Test solution 1 is not more intense than the principal spot in the chromatogram obtained from
Standard solution 2 (0.25%). Spray the plate with 0.1 N iodine TS, allow to stand for 10 minutes, and examine the plate: any spot corresponding to triethylenediamine in the chromatogram obtained from
Test solution 1 is not more intense than the principal spot in the chromatogram obtained from
Standard solution 3 (0.25%). In a valid test, the chromatogram obtained from the
Resolution solution shows a spot due to triethylenediamine clearly separated from the principal spot. Disregard any spot at the origin of any chromatogram.
USP32
Assay
Weigh accurately about 150 mg of Piperazine, and dissolve in 75 mL of glacial acetic acid. Titrate potentiometrically with 0.1 N perchloric acid VS, using a silver-glass electrode system. As the endpoint is approached, warm the solution to 60

to 70

, then complete the titration. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 4.307 mg of C
4H
10N
2.