Physical Composition of Samples

EMR from the source is completely absorbed by a thin layer of molecules at the surface of tablets. Absorption of EMR by surface drug molecules can result in formation 

Of all sample forms, liquid solutions allow drug molecules to the greatest exposure to EMR. The consequence of this is that drugs tend to be more photolabile in solutions than in other sample forms such as solid tablets. This is particularly true for dilute solutions where the absorption and scattering by components in the solution other than drug molecules is minimized. A drug that is stable in powders or tablets may not be stable in liquid solutions. Conversely, a drug that is stable in liquid solution is likely to also be stable in powders and tablets. 

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