Flow-Injection Lucigenin-Cu(III) Complex Chemiluminescence Determination of Cysteine and Glutathione in Pharmaceutical Formulations

A flow injection method for the determination of cysteine (CySH) and glutathione (GSH) amino acids is reported based on lucigenin-diperiodatocuprate(III) complex chemiluminescence (CL) reaction in basic medium. Under optimum conditions, linear calibration curves were obtained in the range of 0.001-30 (R-2 = 0.9998, n = 6) and 0.005-30 mg/L (R-2 = 0.9989, n = 6) with detection limits (S/N = 3) of 2.5 x 10(-4) and 8 x 10(-4) mg/L for CySH and GSH, respectively. The relative standard deviation was 4.1% (n = 11) with injection throughput of 160 per hour. We have applied the developed method to determine CySH and GSH in pharmaceutical samples and compared the results with a spectrophotometric method. Statistical tests such as Student's t- and F-tests were applied for both results with no significant difference observed at a 95% confidence level. The CL reaction of lucigenin-copper(III) complex is also presented.

Automated summary

A flow injection method based on lucigenin-diperiodatocuprate(III) complex chemiluminescence reaction in basic medium was developed for the determination of cysteine and glutathione amino acids. The method showed high sensitivity and accuracy, and was successfully applied to pharmaceutical samples for analysis.