Flow-through UV spectrophotometric sensor for determination of (acetyl)salicylic acid in pharmaceutical preparations.
The solid phase spectrophotometry technique, in which the absorbance of the species of interest sorbed on a solid support is measured directly, was applied to the determination of salicylic acid using flow injection-analysis. Salicylic acid was determined by monitoring of its intrinsic absorbance at 297 nm sorbed on Sephadex QAE A-25 resin placed in an appropriate flow-through cell. The method proposed improves the selectivity compared with the corresponding solution-phase method and the sensitivity is increased by a factor of 30 or more. The flow-through sensor proposed allows working with several calibration lines simply by varying the sample volume injected. Thus, linear dynamic ranges from 1 to 20 and from 2 to 40 microg ml(-1) can be obtained by using 1000 and 300 microl, respectively, with detection limits being 0.064 and 0.135 microg ml(-1). Relative Standard Deviations (RSDs) of 0.52 and 0.38%, and sampling frequencies of 18 and 25 h(-1), respectively, were also achieved. The sensor also allows the indirect determination of acetylsalicylic acid previous hydrolysis on-line to salicylic acid. For acetylsalicylic acid, a linear dynamic range from 5 to 120 microg ml(-1) and 25 h(-1) of sampling frequency (300 microl of sample volume) were obtained. The proposed flow-through sensor has been successfully applied to the determination of both analytes in pharmaceutical preparations.
Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaén, Jaén 23071, Spain.
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Ruiz-Medina
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Fernández-de Córdova
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Ortega-Barrales
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Molina-Díaz
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis*; D001241:Aspirin / Q000032:analysis*; D017022:Flow Injection Analysis / Q000295:instrumentation*; D006868:Hydrolysis; D004364:Pharmaceutical Preparations / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D004364:Pharmaceutical Preparations; D001241:Aspirin