Heterogeneous catalysis of aspirinl degradation in chloroformic solution and its relationship to the determination of salicylic acid in buffered aspirin products
✍ Scribed by David E. Guttman
- Publisher
- John Wiley and Sons
- Year
- 1968
- Tongue
- English
- Weight
- 454 KB
- Volume
- 57
- Category
- Article
- ISSN
- 0022-3549
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✦ Synopsis
Dificulties and spurious results were encountered when buffered aspirin tablets were subjected to the official test for salicylic acid. The present investigation was concerned with this problem and with a characterization of the behaviors of aspirin and salicylic acid in chloroformic solution in contact with chloroform-insoluble agents which are commonly used as b d e r i n g agents in buffered aspirin tablets. Two phenomena were studied which can have manifestations of analytical importance. Both aspirin and salicylic acid were found to be adsorbed by solids such as magnesium carbonate, aluminum glycinate, aluminum hydroxide, and magnesium trisilicate. Rate studies showed that chloroformic solutions of as irin in contact with solid buffers were unstable and generated at a relatively rapitfrate a compound with the chromatographic characteristics of salicylic acid. The rate of generation was shown to be due neither to the water or ethanol content of the chloroform nor to the presence of dissolved buffer. Rather, it was demonstrated that catalysis was due to solid surfaces. The addition of citric acid monohydrate to such systems resulted in an almost complete abolition of adsorption and catalysis.
LIMIT TEST for free salicylic acid in aspirin A tablets is described in the USP XVII (1) and is based on the procedure which was developed and described by Weber and Levine (2).