title: Simultaneous determination of ascorbic acid, caffeine and paracetamol in drug formulations by differential-pulse voltammetry using a glassy carbon electrode.
abstract: A simple, rapid and accurate method for the simultaneous determination of ascorbic acid, caffeine and paracetamol in drug formulations has been developed. Peak currents were measured with a glassy carbon electrode at +0.350, +0.618 and +1.425 V versus a saturated calomel electrode for ascorbic acid, paracetamol and caffeine, respectively. Perchloric acid (0.1 M) - methanol (1 + 1) was used both as a solvent and supporting electrolyte. The optimum modulation amplitude, pulse repeat time and scan rate of the polarographic analyser were found to be 50 mV, 0.5 s and 5 mV s-1, respectively and the linear calibration ranges for ascorbic acid, caffeine and paracetamol were 0-35, 0-50, and 0-55 micrograms ml-1, respectively. The relative standard deviations for 9.30 micrograms ml-1 of ascorbic acid, 8.50 micrograms ml-1 of caffeine and 7.30 micrograms ml-1 of paracetamol were 1.3, 2.5 and 0.7%, respectively. Results are reported for several commercially available drugs.
authors.forename: O W
authors.initials: OW
authors.lastname: Lau
authors.forename: S F
authors.initials: SF
authors.lastname: Luk
authors.forename: Y M
authors.initials: YM
authors.lastname: Cheung
mesh_terms: D000082:Acetaminophen / Q000032:analysis*; D000700:Analgesics / Q000032:analysis*; D001205:Ascorbic Acid / Q000032:analysis*; D002110:Caffeine / Q000032:analysis*; D002244:Carbon; D004566:Electrodes; D005898:Glass; D011786:Quality Control
chemical_list: D000700:Analgesics; D000082:Acetaminophen; D002110:Caffeine; D002244:Carbon; D001205:Ascorbic Acid