Spectrophotometric and Electroanalytical Determination of Prilocaine

Sensitive and selective spectrophotometric and voltammetric methods for the determination of Prilocaine have been developed. The spectrophotometric method was based on the formation of colored ion-pair complexes between Prilocaine and each of Bromothymol Blue (BTB) and Bromocresol. Green (BCG), the complexes formed have been extracted with chloroform and exhibit maximum absorbance at 416 and 420 nm for BTB and BCG, respectively. Beer’s law was obeyed over a wide range (2.0 - 24.5 ppm) for BTB, and (2.0 - 26.5) ppm using BCG, with molar absorptivities (s) equals 1.68 >< 104 L mol" cm" and 1.83 x 104 L mol" cm" using BTB and BCG respectively. RSD were found to be 0.61% and 0.53% for BTB and BCG respectively. All factors affecting the color formation, extraction, sensitivity and reproducibility of the method were studied, among which are; effect of pH, type of solvent, shaking time, amount of buffer, concentration of dye, temperature, stability of complex formed, and stoichiometry. The voltammetric method was based on direct determination of Prilocaine using differential-pulse adsorptive cathodic stripping voltammetry (DP-AdCSV) in basic medium using Britton-Robinson (BR) buffer. The factors affecting the sensitivity of the method has been investigated to optimize the determination method, among these factors are: pH, accumulation potential, accumulation time, scan rate, drop size, and pulse amplitude. Calibration graph was found to be linear over the range (0.16-21.6 ppm) (6.2 >< 10⁷-8.4 x 10⁵ M) with detection limit equals 0.16 ppm, and RSD of 0.68%. The suggested methods were compared with other existing spectrophotometric, chromatographic and electroanalytical methods. It was found that, the suggested methods were relatively sensitive, accurate, precise, and could be applied successfully for the determination of Prilocaine without any interference from the drug ingredients.