药品中用高分辨TGA表征其结构水和自由水检测方案

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TAInstruments Thermal Analysis & Rheology THERMAL SOLUTIONS SEPARATION OF FREE AND BOUND WATER IN PHARMACEUTICALS The amount of moisture in pharmaceutical formulations isan important quality control parameter because it can affecttheir long-term stability and ultimate effectiveness as wellas short-term processability. Techniques such as KarlFischer titration， moisture evolution analysis (1，2)， andthermogravimetric analysis (TGA) have been used fordetermining pharmaceutical moisture levels. However，these techniques often have trouble differentiatingbetween“free”surface water (the source of problems) andbound water present in the chemical formulation. The resolution (separation) of successive weight losses inTGA can be improved by varying the heating rate duringthe experiment. This approach， called high resolution TGA(3)， enables the weight losses associated with“free"andbound water to be separated and quantified as shown inFigures 1 and 2. Figure 1 represents the conventional TGAresults at 10°C/minute. The derivative curve (broken line)indicates that there are two components associated withthe weight loss below 100°℃. However， separation andquantitation is difficult. Using high resolution TGA on theother hand， provides sufficient separation (Figure2) tomeasure the surface water. REFERENCES： 1. TA Instruments Applications BriefTA-114. 2. TA Instruments Applications BriefTA-116. 3. High Resolution TGA： Theory and Applications； TA Instruments Publication TA-023. Acknowledgement： This brief is based on work by N. Hawkins， TA Instruments Applications Laboratory (UK). For more information or to place an order， contact： TA Instruments， Inc.， 109 Lukens Drive， New Castle， DE 19720， Telephone： (302) 427-4000， Fax：(302) 427-4001TA Instruments S.A.R.L.， Paris， France， Telephone： 33-01-30489460， Fax： 33-01-30489451TA Instruments N.V./S.A.， Gent， Belgium， Telephone： 32-9-220-79-89，Fax： 32-9-220-83-21TA Instruments GmbH， Alzenau， Germany， Telephone： 49-6023-30044， Fax： 49-6023-30823TA Instruments， Ltd.，Leatherhead， England， Telephone： 44-1-372-360363， Fax： 44-1-372-360135TA Instruments Japan K.K.， Tokyo， Japan， Telephone： 813-5434-2771， Fax： 813-5434-2770 Internet： http：//www.tainst.com TS-17A TS- TAInstrumentsThermal Analysis & RheologyA SUBSIDIARY OF WATERS CORPORATION