Factor Xa (Activated Factor X) for Anti-Factor Xa Test
—Factor Xa is the proteolytic enzyme derived from bovine plasma, and it cleaves prothrombin to form thrombin. It is a glycoprotein having a molecular weight of 40,000. One Factor Xa Unit is the amount of activated endogenous Factor X (55,000 Da when nonactivated) that is contained in 1 mL of normal plasma. Russell's viper venom is used to activate the enzyme, and is then removed. The preparation is stabilized and lyophilized.
Factor Xa is free of thrombin at the concentration used in the test. When tested against pure fibrinogen, no clotting takes place within 24 hours. It has not less than 40 Factor Xa Units per mg of protein, and exhibits 90% homogeneity when tested by disk electrophoresis.
One Factor Xa Unit per mL gives a 15-second clotting time when tested in the following manner. Mix 0.1 mL of a saturated solution of cephalin (derived from rabbit brain-acetone powder or from an equivalent amount of rabbit brain thromboplastin) in 0.1 mL of citrated bovine plasma and 0.1 mL of 0.025 M calcium chloride. Immediately add 0.1 mL of a solution of factor Xa (1 in 10), and incubate at 37
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Fast Blue B Salt,
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Loss on drying
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Absorbance—
Dissolve 50 mg in 100 mL of water. In a second container dissolve 100 mg of 2-naphthol in 100 mL of 2-methoxyethanol. Pipet 5 mL of the test solution and 10 mL of the 2-naphthol solution into a 100-mL volumetric flask, and dilute with acetone to volume. For the blank, pipet 5 mL of water and 10 mL of 2-naphthol solution into a second 100-mL volumetric flask, and dilute with acetone to volume. Determine the absorbance of the test solution in a 1-cm cell at the wavelength of maximum absorbance at about 545 nm, with a suitable spectrophotometer, using the blank to set the instrument: the absorbance is not less than 0.80.
Fast Blue BB Salt,
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Chloride—
Transfer about 80 mg, accurately weighed, to a suitable beaker. Add 25 mL of acetone, 25 mL of water, and 500 mg of sodium nitrate. Stir until solution is complete. Titrate with 0.01 N silver nitrate VS, determining the endpoint potentiometrically. Perform a blank determination and make any necessary correction. Not less than 15.0% of chloride is found.
Fast Green FCF,
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FD&C Blue No. 1 (Brilliant Blue),
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Ferric Ammonium Citrate
—Thin, transparent, garnet-red scales or granules or brownish-yellow powder. Is deliquescent and is affected by light. Very soluble in water; insoluble in alcohol.
Assay—
Accurately weigh about 1 g, dissolve in 25 mL of water in a glass-stoppered flask, add 5 mL of hydrochloric acid and 4 g of potassium iodide, insert the stopper in the flask, and allow to stand in the dark for 15 minutes. Add 100 mL of water, and titrate the liberated iodine with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the endpoint is approached. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N sodium thiosulfate is equivalent to 5.585 mg of Fe: between 16.5% and 18.5% is found.
Ferric citrate—
To 250 mg dissolved in 25 mL of water add 1 mL of potassium ferrocyanide TS: no blue precipitate is formed.
Tartrate—
Dissolve 1 g in 10 mL of water, add 1 mL of potassium hydroxide TS, boil to coagulate the ferric hydroxide, adding more potassium hydroxide TS, if necessary, to precipitate all of the iron, filter, and slightly acidify the filtrate with glacial acetic acid. Add 2 mL of glacial acetic acid, and allow to stand for 24 hours: no crystalline white precipitate is formed.
Lead
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Ferric Ammonium Sulfate,
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Ferric Chloride,
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Ferric Nitrate,
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Ferric Sulfate,
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Assay—
Accurately weigh about 700 mg, and dissolve it in a mixture of 50 mL of water and 3 mL of hydrochloric acid in a glass-stoppered flask. Add 3 g of potassium iodide, and allow to stand in the dark for 30 minutes. Then dilute with 100 mL of water, and titrate with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the endpoint is approached. Each mL of 0.1 N sodium thiosulfate is equivalent to 5.585 mg of Fe: not less than 21.0% and not more than 23.0% is found.
Insoluble matter (Reagent test)—
A 10-g portion, dissolved in a mixture of 100 mL of water and 5 mL of sulfuric acid, shows not more than 2 mg of insoluble matter (0.02%).
Chloride—
Dissolve 1 g by warming with a mixture of 10 mL of water and 1 mL of nitric acid, add 4 mL of additional nitric acid, and dilute with water to 50 mL. To 25 mL add 1 mL of phosphoric acid and 1 mL of silver nitrate TS. Any turbidity does not exceed that produced in a control containing 0.01 mg of chloride ion (Cl), 1 mL of nitric acid, 1 mL of phosphoric acid, and 1 mL of silver nitrate TS (0.002%).
Ferrous iron—
Dissolve 4 g by warming with 50 mL of dilute sulfuric acid (1 in 10), cool, and titrate with 0.1 N potassium permanganate: not more than 0.16 mL is required to produce a permanent pink color (0.02% as Fe+2).
[Note—Because the reagents used in the tests for Copper and Zinc may contain excessive amounts of copper and zinc, they should first be purified by extracting with Dithizone Extraction Solution(see Lead
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Copper—
Dissolve 1.2 g in 100 mL of water. To 10 mL add 50 mL of a solution containing 5 g of ammonium tartrate and 5 mL of ammonium hydroxide. Add 10 mL of Standard Dithizone Solution (see Lead
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Zinc—
To the combined acid extracts saved from the Copper test, add 0.5 M sodium acetate to bring the pH between 5.0 and 5.5, and then add 1 mL of 0.1 N sodium thiosulfate. Add 10 mL of Standard Dithizone Solution (see Lead
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Nitrate—
Dissolve 10 g in 100 mL of dilute sulfuric acid (1 in 100), heat to boiling, and pour, slowly, into a mixture of 140 mL of water and 50 mL of stronger ammonia TS. Filter through a folded filter while still hot, wash with hot water until the volume of the filtrate is 300 mL, mix, and cool. To 15 mL of this solution add 1 mL of sodium chloride solution (1 in 200), 0.10 mL of indigo carmine TS, and 15 mL of sulfuric acid. The blue color is not completely discharged at the end of 5 minutes (0.01%).
Substances not precipitated by ammonia—
Evaporate to dryness 30 mL of the filtrate obtained in the test for Nitrate, and ignite gently: the weight of residue does not exceed 1 mg (0.10%).
Ferrocyphen
(Dicyano-bis (1,10-phenantroline) iron (II) Complex),
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Water, Method I
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Ferrous Chloride Tetrahydrate
(Iron (II) Chloride Tetrahydrate),
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Ferrous Sulfate,
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Ferrous Ammonium Sulfate,
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Ferulic Acid (4-Hydroxy-3-methoxycinnamic acid),
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Fibroblast Growth Factor-2—
Use a suitable grade.
[Note—A suitable grade can be obtained from Roche Diagnostics Corporation, www.roche-diagnostics.com. ]
Filter Paper, Quantitative
—For the Mercuric Bromide Test Paper used in testing for arsenic, use Swedish O filter paper or other makes of like surface, quality, and ash.
Fluorene,
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Solubility test—
One g dissolves in 10 mL of acetone to yield a clear and complete solution.
Melting range
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9-Fluorenylmethyl Chloroformate,
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Fluorescamine,
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Assay—
Dissolve about 600 mg in 75 mL of dimethylformamide, and titrate with 0.1 N lithium methoxide to a blue endpoint, using 1% thymol blue in dimethylformamide as the indicator. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N lithium methoxide is equivalent to 27.83 mg of C17H10O4. Not less than 99% is found.
Loss on drying
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4¢-Fluoroacetophenone,
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Assay—
Inject an appropriate specimen into a suitable gas chromatograph (see Chromatography
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Refractive index
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Formaldehyde Solution,
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Formamide,
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Preparation for Digitoxin Assay—
To ensure freedom from ammonia, treat Formamide as follows. Shake a suitable quantity of formamide with about 10% of its weight of anhydrous potassium carbonate for 15 minutes, and filter. Distill the filtrate in an all-glass apparatus under vacuum at a pressure of about 25 mm of mercury or less. Reject the first portion of distillate containing water, and collect the fraction that boils at about 115
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Formamide, Anhydrous,
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Formic Acid,
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Formic Acid, 96 Percent,
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Formic Acid, Anhydrous
—Use ACS reagent grade Formic Acid, 96 Percent.
Change to read:
Fuchsin, Basic
(Basic Red 9, Parafuchsin Hydrochloride),
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Fuller's Earth, Chromatographic
—(Very Fine and Moderately Coarse)—Gray or grayish-white powder or granules consisting mainly of hydrous aluminum-magnesium silicate.
Powder fineness—
See Powder Fineness
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Soluble matter—
Twenty g, treated with 50 mL of cold water and filtered, yields not more than 60 mg of residue upon evaporation of the filtrate (0.3%). A second 20-g portion, treated with 50 mL of cold alcohol and filtered, yields not more than 14 mg upon evaporation of the filtrate (0.07%).
Loss on drying
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[Note—Adjust the water content, if necessary, by drying in vacuum at room temperature, restoring the water required, and equilibrating by shaking for 2 hours. ]
Furfural
(2-Furancarboxyaldehyde; 2-Furaldehyde),
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
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