L-Arginine CAS 74-79-3 (H-Arg-OH) Assay 98.5~101.0% Factory (AJI 97/USP/BP/FCC Standard)

DEFINITION
Arginine contains not less than 98.5 per cent andnot more than the equivalent of 101.0 per cent of(S)-2-amino-5-guanidinopentanoic acid, calculated withreference to the dried substance.
CHARACTERS
Appearance: white or almost white, crystalline powder or colourless crystals, hygroscopic. Solubility: freely soluble in water, very slightly soluble in ethanol (96 percent).
IDENTIFICATION
First identification: A, C.
Second identification: A,B,D,E
A. It complies with the test for specific optical rotation (seeTests).
B. Solution S (see Tests) is strongly alkaline (2.2.4).
C. Examine by infrared absorption spectrophotometry (2.2.24), comparing with the spectrum obtained witharginine CRS.Examinethesubstancespreparedasdiscs.
D. Examine the chromatograms obtained in the test for ninhydrin-positive substances. The principal spot in the chromatogram obtained with test solution (b) is similarin position, colour and size to the principal spot in thechromatogram obtained with reference solution (a).
E. Dissolve about 25 mg in 2 ml of water R. Add 1ml of α-naphthol solution R and 2 ml of a mixture of equal volumes of strong sodium hypochlorite solution R and water. A red colour develops.
TESTS
Solution S. Dissolve2.5gindistilled water Rand dilute to50 ml with the same solvent.
Appearance of solution. Solution S is clear (2.2.1)and not more intensely coloured than reference solution BY6 (2.2.2, Method II).
Specific optical rotation (2.2.7). Dissolve 2.00 g in hydrochloric acid R1 and dilute to 25.0 ml with the same acid. The specific optical rotation is + 25.5 to + 28.5, calculated with reference to the dried substance.
Ninhydrin-positive substances. Examine by thin-layer chromatography (2.2.27), using a TLC silica gel plate R.
Test solution (a). Dissolve 0.10 g of the substance to be examined in dilute hydrochloric acid Rand dilute to 10 ml with the same acid.
Test solution (b). Dilute 1 ml of test solution (a) to 50 ml with water R.
Reference solution (a). Dissolve 10 mg of arginine CRS in 0.1 M hydrochloric acid and dilute to 50 ml with the same acid.
Reference solution (b). Dilute 5 ml of test solution (b) to 20 ml with water R.
Reference solution (c). Dissolve 10 mg of arginine CRS and10 mg of lysine hydrochloride CRS in0.1 M hydrochloric acid and dilute to 25 ml with the same acid.
Apply to the plate 5 μl of each solution. Allow the plate to dry in air. Develop over a path of 15 cm using a mixture of 30 volumes of concentrated ammonia R and 70 volumes of 2-propanol R. Dry the plate at 100°C to105°C until the ammonia disappears completely. Spray with ninhydrin solution R and heat at 100°C to 105°C for 15min. Any spot in the chromatogram obtained with test solution (a), apart from the principal spot, is not more intense than the spotin the chromatogram obtained with reference solution (b) (0.5 per cent). The test is not valid unless the chromatogram obtained with reference solution (c) shows two clearly separated spots.
Chlorides (2.4.4). To 5 ml of solution S add 0.5 ml of dilute nitric acid R and dilute to 15 ml with water R. The solution complies with the limit test for chlorides (200 ppm).
Sulphates (2.4.13). To 10 ml of solution S, add 1.7 ml of dilute hydrochloric acid R and dilute to 15 ml with distilled water R. The solution complies with the limit test forsulphates (300 ppm).
Ammonium (2.4.1). 50 mg complies with limit test B for ammonium (200 ppm). Prepare the standard using 0.1 ml of ammonium standard solution (100 ppm NH4) R.
Iron (2.4.9). In a separating funnel, dissolve 1.0 g in 10 ml of dilute hydrochloric acid R. Shake with three quantities, each of 10 ml, ofmethyl isobutyl ketone R1, shaking for 3 min each time. To the combined organic layers add 10 ml of water Rand shake for 3 min. The aqueous layer complies with the limit test for iron (10 ppm).
Heavy Metals (2.4.8). Dissolve 2.0g in water R and dilute to 20ml with the same solvent. 12ml of the solution complies with limit test A for heavy metals (10ppm).Prepare the standard using lead standard solution(1ppm Pb) R.
Loss on Drying (2.2.32). Not more than 0.5 percent, determined on 1.000 g by drying in an oven at 105℃
Sulphated ash (2.4.14). Not more than 0.1 percent,determined on 1.0 g.
ASSAY
Dissolve 0.150 g in 50 ml of water R. Using 0.2ml of methyl red mixed solution Ras indicator, titrate with 0.1 M hydrochloric acid until the colour changes from green toviolet-red.
1ml of 0.1 M hydrochloric acidis equivalent to 17.42 mg of C6H14N4O2.
STORAGE
Store protected from light.