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【求助】求美国药典，VB12与VB2的含量测定方法
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| 求美国药典，VB12与VB2的含量测定方法 |
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kerxin(金币+3): 2010-09-07 12:14:37
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Cyanocobalamin C63H88CoN14O14P 1355.37 Vitamin B12. Vitamin B12 [68-19-9]. » Cyanocobalamin contains not less than 96.0 percent and not more than 100.5 percent of C63H88CoN14O14P, calculated on the dried basis. Packaging and storage— Preserve in tight, light-resistant containers, and store at controlled room temperature. USP Reference standards 11 — USP Cyanocobalamin RS. Identification— A: The absorption spectrum of the solution employed for measurement of absorbance in the Assay exhibits maxima within ±1 nm at 278 nm and 361 nm and within ±2 nm at 550 nm. The ratio A361/A278 is between 1.70 and 1.90, and the ratio A361/A550 is between 3.15 and 3.40. B: Fuse about 1 mg with about 50 mg of potassium pyrosulfate in a porcelain crucible. Cool, break up the mass with a glass rod, add 3 mL of water, and dissolve by boiling. Add 1 drop of phenolphthalein TS, and add sodium hydroxide solution (1 in 10), dropwise, until just pink. Add 500 mg of sodium acetate, 0.5 mL of 1 N acetic acid, and 0.5 mL of nitroso R salt solution (1 in 500): a red or orange-red color appears at once. Add 0.5 mL of hydrochloric acid, and boil for 1 minute: the red color persists. C: Dissolve about 5 mg in 5 mL of water in a 50-mL distilling flask connected with a short, water-cooled condenser. To the flask add 2.5 mL of hypophosphorous acid, close, boil gently but short of distillation for 10 minutes, then distill 1 mL into a test tube containing 1 mL of sodium hydroxide solution (1 in 50). To the test tube add 4 drops of cold saturated ferrous ammonium sulfate solution, shake gently, then add about 30 mg of sodium fluoride, and bring the contents to a boil. Immediately add, dropwise, 5 N sulfuric acid until a clear solution results, then add 3 to 5 drops more of the acid: a blue or blue-green color develops within a few minutes. Loss on drying 731 — Heat about 25 mg, accurately weighed, in a suitable vacuum drying apparatus at 105 and at a pressure of not more than 5 mm of mercury for 2 hours, cool, and weigh: it loses not more than 12.0% of its weight. Pseudo cyanocobalamin— Dissolve 1.0 mg in 20 mL of water contained in a small separator, add 5 mL of a mixture of equal volumes of carbon tetrachloride and m-cresol, and shake well for about 1 minute. Allow to separate, draw off the lower layer into a second small separator, add 5 mL of 5 N sulfuric acid, shake well, and allow to separate completely (the complete separation of the layer may be facilitated by centrifuging): the separated upper layer is colorless or has no more color than a mixture of 0.15 mL of 0.10 N potassium permanganate and 250 mL of water. Assay— Transfer about 30 mg of Cyanocobalamin, accurately weighed, with the aid of water to a 1-L volumetric flask, dilute with water to volume, and mix. Dissolve an accurately weighed quantity of USP Cyanocobalamin RS in water, and dilute quantitatively and stepwise with water to obtain a Standard solution having a known concentration of about 30 µg per mL. Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 361 nm, with a suitable spectrophotometer, using water as the blank. Calculate the quantity, in mg, of C63H88CoN14O14P in the Cyanocobalamin taken by the formula: C(AU / AS) in which C is the concentration, in µg per mL, of USP Cyanocobalamin RS in the Standard solution; and AU and AS are the absorbances of the solution of Cyanocobalamin and the Standard solution, respectively. Auxiliary Information— Please check for your question in the FAQs before contacting USP. Topic/Question Contact Expert Committee Monograph Curtis Phinney 1-301-816-8540 (DSN05) Dietary Supplements - Non-Botanicals Reference Standards Lili Wang, Technical Services Scientist 1-301-816-8129 RSTech@usp.org USP32–NF27 Page 2036 Pharmacopeial Forum: Volume No. 31(5) Page 1350 Riboflavin C17H20N4O6 376.36 Riboflavine. Riboflavine [83-88-5]. » Riboflavin contains not less than 98.0 percent and not more than 102.0 percent of C17H20N4O6, calculated on the dried basis. Packaging and storage— Preserve in tight, light-resistant containers. USP Reference standards 11 — USP Riboflavin RS. Identification— A solution of 1 mg in 100 mL of water is pale greenish yellow by transmitted light, and has an intense yellowish-green fluorescence that disappears upon the addition of mineral acids or alkalies. Specific rotation 781S : between –115 and –135 . Test solution: 5 mg per mL, in 0.05 M sodium hydroxide free from carbonate. Measure the specific rotation within 30 minutes of preparation. Loss on drying 731 — Dry about 500 mg at 105 for 2 hours: it loses not more than 1.5% of its weight. Residue on ignition 281 : not more than 0.3%. Limit of lumiflavin— Prepare alcohol-free chloroform just prior to use, as follows. Shake 20 mL of chloroform gently but thoroughly with 20 mL of water for 3 minutes, draw off the chloroform layer, and wash twice more with 20-mL portions of water. Finally, filter the chloroform through a dry filter paper, shake it for 5 minutes with 5 g of powdered anhydrous sodium sulfate, allow the mixture to stand for 2 hours, and decant or filter the clear chloroform. Shake 25 mg of Riboflavin with 10 mL of the alcohol-free chloroform for 5 minutes, and filter: the absorbance of the filtrate, determined in 1-cm cells at a wavelength of 440 nm, with a suitable spectrophotometer, alcohol-free chloroform being used as the blank, does not exceed 0.025. Assay— [note—Conduct the entire procedure without exposure to direct sunlight.] Place about 50 mg of Riboflavin, accurately weighed, in a 1000-mL volumetric flask containing about 50 mL of water. Add 5 mL of 6 N acetic acid and sufficient water to make about 800 mL. Heat on a steam bath, protected from light, with frequent agitation until dissolved. Cool to about 25 , dilute with water to volume, and mix. Dilute this solution quantitatively and stepwise with water to bring it within the operating sensitivity of the fluorometer used. In the same manner, prepare a Standard solution to contain, in each mL, an accurately weighed quantity, of USP Riboflavin RS, equivalent to that of the Riboflavin solution prepared as directed above, and measure the intensity of its fluorescence in a fluorometer at about 530 nm. (An excitation wavelength of about 444 nm is preferable.) Immediately after the reading, add to the solution about 10 mg of sodium hydrosulfite, stirring with a glass rod until dissolved, and at once measure the fluorescence again. The difference between the two readings represents the intensity of the fluorescence due to the Standard. Similarly, measure the intensity of the fluorescence of the final solution of the Riboflavin being assayed at about 530 nm, before and after the addition of sodium hydrosulfite. Calculate the quantity, in µg per mL, of C17H20N4O6 in the final solution of Riboflavin taken by the formula: C(IU / IS) in which C is the concentration, in µg per mL, of USP Riboflavin RS in the final solution of the Standard, and IU and IS are the corrected fluorescence values observed for the solutions of the Riboflavin and Standard, respectively. Auxiliary Information— Please check for your question in the FAQs before contacting USP. Topic/Question Contact Expert Committee Monograph Curtis Phinney 1-301-816-8540 (DSN05) Dietary Supplements - Non-Botanicals Reference Standards Lili Wang, Technical Services Scientist 1-301-816-8129 RSTech@usp.org USP32–NF27 Page 3497 Pharmacopeial Forum: Volume No. 30(3) Page 929 Chromatographic Column— RIBOFLAVIN Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27. |
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