Automated stopped-flow system in pharmaceutical and clinical analysis : Kinetic determination of acetaminophen in formulations and serum by using the iron(II)—2,4,6-tris(2-pyridyl)-s-triazine
✍ Scribed by M.A. Koupparis; K.E. Evagorou; T.P. Hadjiioannou
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- English
- Weight
- 777 KB
- Volume
- 224
- Category
- Article
- ISSN
- 0003-2670
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✦ Synopsis
The development of automated stopped-flow spectrophotometric systems, their potential in automated routine determinations using kinetic and fast equilibrium techniques and several examples of applications are briefly reviewed. The use of a compact, inexpensive laboratory-made stopped-flow system for the measurement of reaction rates and a fast equilibrium method for the determination of acetaminophen in formulations and serum are described. The reaction-rate method is based on monitoring the oxidation of acetaminophen by iron(II1) in the presence of the chelating agent 2,4,6-tris (P-pyridyl ) -s-triazine to form a highly absorbing complex of iron (II ) . The calibration graph is linear in the range 20-200 pg ml-', with a precision of 0.8-2.6%, a detection limit of 5.5 pg ml-' and a measurement throughput of 120 per hour. Common excipients do not interfere and the analysis of commercial formulations gave results similar to those of a reference method. The optimization of the experimental conditions was done by a kinetic study of the reaction and some kinetic parameters are given.
The method for the determination of acetaminophen in serum is based on a rapid measurement of the absorbance of the reaction mixture after a delay time of 15 s in the presence of chlorpromazine, which catalyses the reaction. Acetaminophen is isolated by extraction with ethyl acetate and the calibration graph is linear in the range 0.5-6 pg ml-' with a detection limit of 0.04 pg ml-' and a precision of 1.5%. The proposed method showed a decreased interference from drugs that also react with iron (III).
Automated analysers of various types have been developed and widely used in recent years because of increasing analytical demands and improvements in technology. Kinetic methods exhibit some advantages over equilibrium methods [ 1 ] that make them very attractive in the development of analytical methodology. The automation of this mode of analysis is highly desirable and it has been accomplished to varying extents in several laboratory and commercial automated systems.