Search

A novel and sensitive flow-injection chemiluminescence (CL) method for the determination of metformin in pharmaceutical formulations over the range of 7 × 10−9–3 × 10−5 g mL−1 is proposed in this article. The method is based on the CL produced during the oxidation of N-bromosuccinimide (NBS) in alkaline medium in the presence of fluorescein as an effective energy transfer agent. Use of cetyltrimethylammonium bromide (CTAB) as a sensitizer enhances the signal magnitude about 100 times. The detection limit is 2.3 × 10−9 g mL−1 (3σ) with a relative standard deviation of 2.7% (n = 11) at 1 × 10−7 g mL−1 metformin. Ninety samples can be determined per hour. The method was evaluated by carrying out a recovery study and by the analysis of commercial formulations. The results obtained compared well with those obtained by pharmacopoeia method and demonstrated good accuracy and precision. The possible reaction mechanism of the CL in the system is also discussed briefly. [ABSTRACT FROM AUTHOR]

In this paper, a novel flow-injection chemiluminescence (CL) system for the determination of urea is described. It is based on the CL reaction of urea and N-bromosuccinimide (NBS) in alkaline medium. The CL intensity was greatly enhanced in the presence of dichlorofluorescein. The CL intensity was linear with an urea concentration of 6 × 10[SUP-6] mol/L ∼ 1 × 10[SUP- 3] mol/L, the detection limit being 2.7 × 10[SUP-6] mol/L (3 s/r). The whole process, including injection, detection and washing, could be completed in 1 min with a relative standard deviation of less than 5%. The proposed method is rapid, simple and suitable automatic and continuous analysis. This method has been applied satisfactorily to the analysis of urea in serum. [ABSTRACT FROM AUTHOR]