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The quasi-reversible, diffusion controlled behavior of rosmarinic acid (RA) on a disposable pencil graphite electrode (PGE) was established by cyclic voltammetry. Using the anodic oxidation peak presented by RA on the PGE a differential pulse voltammetric (DPV) method was developed for the quantitative determination of RA. The linear range was 10 −8 -10 −5 M RA and the detection and quantification limits were 7.93 × 10 −9 M and 2.64 × 10 −8 M RA, respectively. The applicability of the developed method was tested by recovery studies and by the assessment of the total polyphenolic contents (TPC DPV ) of green, white and black Turkish teas, which were found to be 40.74, 30.04 and 23.97 mg rosmarinic acid equivalent/g dry tea, respectively. These results were in good agreement with those obtained by the Folin-Ciocalteu method. The developed method is a sensitive and cheap tool for the rapid and precise evaluation of TPC DPV of tea samples.

Due to the importance of B

Abstract:The present paper describes the use of a disposable pencil graphite electrode (PGE) for the voltammetric determination of famotidine. Cyclic voltammetric studies using different supporting electrolytes emphasized an irreversible oxidation of famotidine on the PGE. The electrode process is diffusion-controlled and pH-dependent. Differential pulse voltammetry (DPV) in phosphate buffer solution of pH 6.81 was employed for famotidine's quantitative determination. The developed DPV method using the inexpensive, disposable PGE was successfully applied to the simple and rapid determination of famotidine from pharmaceuticals.