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C11H12N2O2 204.23

l-Tryptophan [73-22-3].
» Tryptophan contains not less than 98.5 percent and not more than 101.5 percent of C11H12N2O2, as l-tryptophan, calculated on the dried basis.
Packaging and storage— Preserve in well-closed containers.
Specific rotation 781S: between 29.4 and 32.8.
Test solution: 10 mg per mL, in water (heat gently to dissolve, if necessary).
pH 791: between 5.5 and 7.0, in a solution (1 in 100).
Loss on drying 731 Dry it at 105 for 3 hours: it loses not more than 0.3% of its weight.
Residue on ignition 281: not more than 0.1%.
Chloride 221 A 0.73-g portion shows no more chloride than corresponds to 0.50 mL of 0.020 N hydrochloric acid (0.05%). [note—Gently heat the sample preparation to dissolve, if necessary.]
Sulfate 221 A 0.33-g portion shows no more sulfate than corresponds to 0.10 mL of 0.020 N sulfuric acid (0.03%). [note—Gently heat the sample preparation to dissolve, if necessary.]
Iron 241: 0.003%.
Assay— Transfer about 200 mg of Tryptophan, accurately weighed, to a 125-mL flask, dissolve in a mixture of 3 mL of formic acid and 50 mL of glacial acetic acid, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 20.42 mg of C11H12N2O2.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Curtis Phinney

(DSN05) Dietary Supplements - Non-Botanicals
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 3824
Pharmacopeial Forum: Volume No. 33(6) Page 1214
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.