Electrophoresis, Vol.35, No.20, 2951-2958, 2014
Rapid and sensitive determination of free thiols by capillary zone electrophoresis with near-infrared laser-induced fluorescence detection using a new BODIPY-based probe as labeling reagent
A CZE with near-infrared (NIR) LIF detection method has been developed for the analysis of six low molecular weight thiols including glutathione, homocysteine, cysteine, gamma-glutamylcysteine, cysteinylglycine, and N-acetylcysteine. For this purpose, a new NIR fluorescent probe, 1,7-dimethyl-3,5-distyryl-8-phenyl-(4'-iodoacetamido)difluoroboradiaza-s-indacene was utilized as the labeling reagent, whose excitation wavelength matches the commercially available NIR laser line of 635 nm. The optimum procedure included a derivatization step of the free thiols at 45 degrees C for 25 min and CZE analysis conducted within 14 min in the running buffer containing 16 mmol/L pH 7.0 sodium citrate and 60% v/v ACN. The LODs (S/N = 3) ranged from 0.11 nmol/L for N-acetylcysteine to 0.31 nmol/L for gamma-glutamylcysteine, which are better than or comparable to those reported with other derivatization-based CE-LIF methods. As the first trial of NIR CE-LIF method for thiol determination, the practical application of the proposed method has been validated by detecting thiols in cucumber and tomato samples with recoveries of 96.5-104.3%.
Keywords:1,7-Dimethyl-3,5-distyryl-8-phenyl-(4 '-iodoacetamido)difluoroboradiaza-s-indacene;Capillary electrophoresis;Near-infrared laser-induced fluorescence;Thiols