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.
Ruiz-Medina
A
A
Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaén, Jaén 23071, Spain.
Fernández-de Córdova
M L
ML
Ortega-Barrales
P
P
Molina-Díaz
A
A
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