Caffeine-Picrylsulfonate Liquid Membrane Electrode for Selective Determination of Caffeine in Analgesic Preparations
A liquid membrane electrode for caffeine prepared from a solution of caffeine-picrylsulfonate ion-pair complex in 1-octanol is developed.It exhibits Nernstian response in the range of 10-2-10-6 M caffeine with a cationic slope of 59 mV/concentration decade.The electrode has a wide working pH range , fast response time , stable response for at least 30 days, and high selectivity for caffeine in the presence of many organic bases.The results obtained for quantitation of 1-1000 μg mL-1 of caffeine show an average recovery of 99.5percent and a mean standard deviation of 1.3percent.Determination of caffeine in some analgesic preparations gives results in good agreement with those obtained by the United States Pharmacopoela method.
Hassan, Saad S. M.,Ahmed, Mona A.,Saoudi, Moshera M.