Chromotrope 2R Dye as a New Sensitizer for the Chemiluminescence Determination of Codeine and Pholcodine Antitussive Drugs

This study proposes a new chemiluminescence (CL) method in which chromotrope 2R is an enhancer in acidic potassium permanganate’s CL reaction with codeine and pholcodine. Studying the reaction mechanism by UV-Vis, fluorescence, and CL spectra in our previous study showed that chromotrope 2R, after reaction with potassium permanganate, stabilized the Mn(III)-dye complex (Mn(III)- ]3+), making the excited ions of [Mn(III)- ]2+* to be produced more accessible and increase the intensity of the light emitted in the CL reaction. This sensitizing effect was also observed for other compounds such as citric acid, tartaric acid, thiourea, ascorbic acid, naproxen, naltrexone, and oxalic acid. Among these compounds, codeine and pholcodine, which are both antitussive drugs, were selected as analytes in this study. The linear dynamic range (LDR) was found to be 5.0(10-6-4.0(10-3) and 1.0´10-5-1.0´10-3 mol/L, for codeine and pholcodine, respectively. The limit of detection (LOD) for codeine and pholcodine was 1.6´10-6 and 3.4´10-6 mol/L, respectively. The relative standard deviation percentage was calculated at 4.7 and 3.8% for codeine and pholcodine, respectively. To evaluate the effect of dye type on the CL intensity, eight other dyes, including amido black, brilliant blue, orange G, eosin Y, and rhodamine 6G, were also investigated on the CL intensity of codeine and pholcodine. It was found that chromotrope 2R produced the most sensitizing effect. The method was effectively used to determine the codeine in pharmaceuticals and pholcodine in synthetic drug samples.