Resonance Rayleigh scattering for the determination of chlorpromazine and promethazine

Chlorpromazine (CPZ) and promethazine (PZ) can react with potassium ferrioxalate (PF) to form 3:1 ion-association complexes, which can result in a significant enhancement of resonance Rayleigh scattering (RRS) intensity. The maximum scattering peaks are located at 368 nm for CPZ-PF and 370 nm for PZ-PF. The RRS spectroscopic characteristics, the optimum conditions of reactions, and influencing factors have been studied for CPZ-PF and PZ-PF. There is a linear relationship between the RRS intensity and the drug concentration in the range of 0.02-8.00 mu g mL(-1) for CPZ and 0.04-9.00 mu g mL(-1) for PZ, and the detection limits (3 sigma) are 6.6 ng mL(-1) for CPZ and 10.6 ng mL(-1) for PZ. The proposed method has been applied to determine CPZ in urine and serum samples with satisfactory results. Moreover, the reaction mechanism and the reasons for intensity enhancement of RRS have been discussed.