Determination of Nalbuphine Hydrochloride in Pharmaceutical Formulations Using Diperiodatoargentate(III)-Rhodamine-B Chemiluminescence System by Flow Injection Analysis.

A novel method for the analysis of nalbuphine hydrochloride (NAL) is reported based on its enhancement effect on a diperiodatoargentate(III)-rhodamine-B (Ag(III) complex-Rh-B) chemiluminescence (CL) system in an aqueous sulfuric acid medium using flow-injection analysis (FIA). The optimal conditions of the CL reaction were: sulfuric acid, 10 M; Ag(III) complex, 2.0 × 10 M; Rh-B, 2.0 × 10 M; Brij-35, 0.01%; sample loop volume, 300 μL; and flow rate, 3.0 mL/min/stream. The limit of detection (LOD) and limit of quantification (LOQ) were 0.001 and 0.003 mg/L (S/N = 3 and 10); linear calibration range, 5 × 10 - 5.0 mg/L (R = 0.9999) and injection throughput, 150/h. The relative standard deviation (RSD) was from 0.8 - 3.2% over the range studied. The suggested technique was applied for the determination of NAL in pharmaceutical injections, compared with a reported spectrophotometric method, and obtained results were found to be satisfactory. Based on spectrophotometric studies, the most probable mechanism of the CL reaction has been briefly described and drawn schematically.