Characterization of the purity of phytotherapics from secondary vegetal metabolism with small-scale coulometry applied to perillic acid

The use of pure materials in chemical analysis is currently in high demand due to the need to provide reliable measurement results. Phytotherapics are natural products that contain substances of secondary vegetal metabolism. Perillic acid, a monoterpenic acid with anti-inflammatory and anticancer properties, was the phytotherapic chosen to be analyzed in this work for purity by coulometry. Due to the low availability of perillic acid on the market and its high cost, the miniaturization of the coulometric technique was fundamental for characterizing such a substance. The volume of the supporting electrolyte and the mass of the analyte were the main parameters scaled. The coulometric measurement results were obtained by small-scale coulometry by using 3.0 mg of perillic acid (scale reduction of ×100). A mean purity of (94.2 ± 0.8)% (k = 2.13, for an approximately 95% confidence level) was obtained from five replicates. These studies aim in the future to develop the production of certified reference materials from natural products.