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 determination of caffeine (CF), acetylsalicylic acid (ASA) and paracetamol (PCT) in pharmaceutical preparations by partial least-squares (PLS) treatment of a flow-through multisensor based on the integration of the retention and UV detection of the analytes on a solid support. Diode-array spectrophotometry has been used to obtain spectra (240-350 nm) of the analytes retained on C18 bonded phase beads packed in a flow cell. By using a 0.5% pH 1 HClO4 solution as the carrier, the multisensor responds linearly in the measuring 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 data for the multivariate procedure. The statistical parameters obtained by the application of PLS methods at different reaction times were analysed, from which the optimum reaction time for the simultaneous determination of the analytes was selected. In the analysis of real and synthetic samples, precise and accurate values were obtained.