Over a decade ago, microemulsion electrokinetic chromatography was introduced as a novel mode of capillary electrophoresis. However, there has not been publication on the combination of microemulsion electrokinetic chromatography with laser-induced fluorescence detection. In this paper, a preliminary method using microemulsion eletrokinetic chromatography combined with laser-induced fluorescence detection and second derivative electrophoregram was established as a sensitive and selective assay for separation and determination of nine amino acids after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1, 3-diazol. The derivatization and separation conditions were optimized. In the investigated concentration ranges correlation coefficients were better than 0.995. The relative standard deviation (n = 5) of the migration times and peak heights were 0.56-0.76 and 2.21-7.15%, respectively. The detection limits (S/N = 3) were at a neaomolar level (0.32-2.20 nM). The method was applied for the analysis of compound amino acid injection and a Chinese traditional herbal medicine. The recoveries were 95.9-107.9%.
- Amino acids
- Laser-induced fluorescence
- Microemulsion electrokinetic chromatography
- Multiple linear regression
- Second derivative electrophoregram