Abstract
Two chemometric procedures, based on uv-spectrophotometry, are described for the simultaneous determination of paracetamol (acetaminophen) and caffeine in a binary mixture without prior separation. In the first procedure the principle of classical least-squares has been adopted using the function SOLVER of Excel spreadsheet program. After measuring absorbance of the sample mixture,Am, at several selected wavelengths, and calculating the value, Acal, and realizing the minimization condition, the mean % recoveries were 96.36 ± 0.91, and 94.74 ± 3.50 for paracetamol and caffeine respectively. In the second procedure, absorbance measurements were made at the wavelengths 242, 251, and 273 nm for known mixtures of pure paracetamol and caffeine. Two linear calibration equations giving concentration as a function of absorbance were worked out by employing multiple regression via Minitab 14 software program. The mean % recoveries obtained for the sample mixture using the calibrated equations were 96.59 ± 2.16, and 95.48 ± 1.85 for paracetamol and caffeine, respectively. When the official HPLC method was applied analysis of the commercial tablets, the mean % recoveries 97.0 ± 3.2 and 99.2 ± 1.3 for paracetamol and caffeine respectively. Based on the student's t-test, satisfactory agreement was observed when the results of the chemometric procedures were compared with those of the official HPLC method. Furthermore, any of the two chemometric procedures may be employed for the routine analysis of paracetamol-caffeine mixture in tablets. It is clear that there is an advantage of the chemometric procedure over HPLC in terms of simplicity, expense, and rapidity.
