Simultaneous determination of paracetamol, caffeine and acetylsalicylic acid by means of a FI ultraviolet pls multioptosensing device

A simple and rapid analytical procedure is proposed for the simultaneous de termination of caffeine (CF), acetylsalicylic acid (ASA) and paracetamol (P CT) in pharmaceutical preparations by partial least-squares (PLS) treatment of a flow-through multisensor based on the integration of the retention an d UV detection of the analytes on a solid support. Diode-array spectrophoto metry has been used to obtain spectra (240-350 Ka) of the analytes retained on C-18 bonded phase beads packed in a flow cell. By using a 0.5% pH 1 HCl O4 solution as the carrier, the multisensor responds linearly in the measur ing range without requiring additional reagents or derivatization processes and the active microzone is regenerated by using methanol as eluting agent . Spectra of the corresponding analytes were used to provide multivariate d ata for the multivariate procedure. The statistical parameters obtained by the application of PLS methods at different reaction times were analysed, f rom which the optimum reaction time for the simultaneous determination of t he analytes was selected. In the analysis of real and synthetic samples, pr ecise and accurate values were obtained. (C) 1999 Elsevier Science B.V. All rights reserved.