Melting Range or Temperature

For pharmaceutical purposes, the melting range or temperature of a solid... 

For pharmaceutical purposes, the melting range or temperature of a solid is defined as those points of temperature within which the solid coalesces or is completely melted. The general method for this methodology is given in the United States Pharmacopeia as a general test [9]. 

Melting range or temperature. General Test <741>, United States Pharmacopeia, vol. 27, United States Pharmacopeial Convention, Rockville, MD, 2004, pp. 2324-2325. 

Melting Range Determine as directed under Melting Range or Temperature, Appendix IIB. 

D. Add 1 mL of hydrochloric acid to 10 mL of a 1 10 aqueous solution. A crystalline precipitate of saccharin forms. Wash the precipitate well with cold water and dry at 105° for 2 h. The saccharin thus obtained melts between 226° and 230° (see Melting Range or Temperature, Appendix IIB). Assay Not less than 98.0% and not more than 101.0% of C7H8N203S, calculated on the anhydrous basis. 

Melting Range Determine as directed in Procedure for Class la, under Melting Range or Temperature, Appendix KB. Optical (Specific) Rotation Determine as directed under... 

Lead Determine as directed under Lead Limit Test, Appendix IIIB, using a Sample Solution prepared as directed for organic compounds, and 5 p,g of lead (Pb) ion in the control. Melting Range Determine as directed in Procedure for Class II under Melting Range or Temperature, Appendix IIB. Saponification Cloud Test... 

Identification Add 50 mL of 0.5 A alcoholic potassium hydroxide to 500 mg of sample, heat gradually to boiling, and continue boiling for 15 min. Cool, dilute to 200 mL with water, and make the solution strongly acid with 0.5 A hydrochloric acid. Extract with ether, dry the extract with anhydrous sodium sulfate, and then evaporate to dryness on a steam bath. The residue of benzoic acid so obtained melts between 121° and 123° (see Melting Range or Temperature, Appendix IIB). 

A. Add 25 mL of 1 2 hydrochloric acid to about 1.5 g of sample, and dilute to 50 mL with water. Heat to effect complete solution then cool filter on a fine-porosity, sintered-glass crucible wash the precipitate with 2 100 hydrochloric acid, saving the filtrate for Identification Test B and dry the precipitate at 105°. Add 3 mL of water and 7 mL of 1 A sodium hydroxide to 400 mg of the dried precipitate, and stir until solution is complete. Add, dropwise, 2.7 A hydrochloric acid until the solution is just acid to litmus add 1 g of p-nitrobenzyl bromide and 10 mL of alcohol and reflux the mixture for 2 h. Cool, filter, and wash the precipitate with two small portions of a 2 1 alcohol water mixture, followed by two small portions of water. The precipitate, recrystallized from hot alcohol and dried at 105°, melts at about 152° (see Melting Range or Temperature, Appendix IIB). 

Procedure Add 0.4 mL of sample to 20 mL of 2,4-Dinitro-phenylhydrazine Reagent. Mix by swirling, and allow the mixture to stand for 5 min. Collect the precipitate on a filter, and rinse thoroughly with alcohol. Dissolve the precipitate in 20 mL of hot ethylene dichloride, filter, and cool the filtrate in an ice bath until crystallization occurs. Collect the precipitate on a filter. Redissolve the precipitate by refluxing with 30 mL of acetone, filter, and cool the filtrate in an ice bath until crystallization occurs. Collect the precipitate on a filter. The 2,4-di n i trophenyI hydrazone so obtained melts between 185° and 195° (see Melting Range or Temperature, Appendix KB). 

B. The inositol hexaacetate obtained in the Assay melts between 212° and 216° (see Melting Range or Temperature, Appendix IIB). 

Identification Dissolve 500 mg of sample in 10 mL of 1 A sodium hydroxide, boil for 30 min, allow the solution to evaporate to a volume of about 5 mL, and cool. Acidify the solution with 2 A sulfuric acid, collect the crystals on a filter, wash several times with small portions of water, and dry in a desiccator over silica gel. The /p-hydroxybenzoic acid so obtained melts between 212° and 217° (see Melting Range or Temperature, Appendix IIB). 

Melting Range Determine as directed in the Procedure for Class la under Melting Range or Temperature, Appendix IIB. Readily Carbonizable Substances Determine as directed under Readily Carbonizable Substances, Appendix IIB, using 200 mg of sample dissolved in 5 mL of 95% sulfuric acid and kept at 48° to 50° for 10 min. The color is no darker than that of Matching Fluid A. 

B. Mix 25 g of sample with 50 g of a 15% alcoholic potassium hydroxide solution in an Erlenmeyer flask, and reflux for 1 h or until saponification is complete. Cool, add 150 mL of water, and mix. After complete solution of the soap, add 60 mL of 2 A sulfuric acid, and while stirring frequently, heat the mixture until the fatty acids separate cleanly as a transparent layer. Wash the fatty acids with boiling water until free from sulfate, collect them in a small beaker, and warm on a steam bath until the water has separated and the fatty acids are clear. Allow the acids to cool, pour off the water layer, then melt the acids, filter into a dry beaker, and dry at 105° for 20 min. The solidification point of the fatty acids so obtained is not below 54° (see Melting Range or Temperature, Appendix IIB). 

Melting Range or Temperature. . . 842 Arsenic Limit Test... 861... 

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