Flow injection spectrofluorimetric determination of reserpine in tablets by on-line acetone sensitized photochemical reaction

On-line photochemical reaction of reserpine in the presence of acetone was investigated. Acetone was found to speed up the on-line photochemical conve rsion of reserpine into an intensively fluorescent compound. Not only react ion acidity but also the acetate buffer concentration affected the on-line photochemical induced fluorescence signal. Based on the observation an auto mated flow injection photochemical fluorimetric approach was developed. An injected sample zone was carried by a water stream to be merged with a acet ate buffer (pH 3.4) solution containing 0.02% acetone in a knotted PTFE rea ctor (KR), which was freely coiled around a 6-W low pressure mercury lamp. While passing the KR, reserpine was transformed into an intensively fluores cent compound. It was on-line detected in a flow-through cell at the emissi on wavelength of 490 nm and excitation wavelength of 386 nm. At optimized c onditions, a detection limit 0.45 mug 1(-1) was achieved at a sampling rate of 90 h(-1). Eleven determinations of a 0.5 mg 1(-1) reserpine standard so lution gave a R.S.D. of 0.3%. The linear dynamic range of reserpine calibra tion curve was 0.01-0.75 mg 1(-1). The proposed method was applied to assay the reserpine content in tablets and to monitor the dissolution profile or reserpine tablets. Satisfactory results were obtained for both the assays and dissolution studies. (C) 2000 Elsevier Science B.V. All rights reserved .