Desenvolvimento de métodos rápidos para determinação de Codeína, Diclofenaco e seus contra-íons por eletroforese capilar com detecção condutométrica sem contato (CE-C4D)

Abstract

This paper presents new analytical procedures for fast determination (in less than a minute) of codeine (COD), diclofenac (DCF) and its counter-ions sodium, potassium, diethylammonium (DEA) and phosphate by capillary electrophoresis coupled with contactless conductivity detection (CE-C4D). The proposed methods can be used in quality control of raw materials and pharmaceutical formulations which have such compounds in their composition. Two different methods were developed, one for the fast and simultaneous determination DCF and its counter-ions (sodium, potassium and DEA) using TRIS / TAPS 10 mmol L-1 (pH 8.2) as the background electrolyte (BGE), and another for fast determination of DCF, COD and its counter-ions (sodium and phosphate) using TEA / oxalate 10/1,8 mmol L-1 (pH 8.4) as BGE. Both methods had low relative standard deviations of the peak areas and migration times. In the determination of DCF and its counter-ions, the calculated values ranged from 2.1 to 5.7% and from 0.69 to 0.85% and in the determination of DCF and COD between 0.72 to 2.7% and 0 0.23 to 0 39%, respectively. The calculated resolutions for each analyte were the following: 2.06 for sodium, 1.99 for DEA; 4.72 for DCF, and 7.11 for COD. All resolutions can be considered satisfactory. The calibration curves for all analytes showed correlation coefficients greater than 0.992. The results obtained from the commercial pharmaceutical samples analysis using the proposed methods were compared with those obtained by HPLC or flame photometry. At a confidence level of 95%, the calculated t values (paired t-Student test) were lower than the theoretical critical value (2.78, n = 3) in all analysis, which indicates no significant differences between the results of the proposed methods and the standard methods (HPLC or flame photometry).