Signal enhancement of dansyl amino acids by fluorimetric detection with a packed flow cell in microcolumn liquid chromatography

Signal enhancement of dansyl amino acids has been achieved by fluorimetric detection with a packed flow cell in microcolumn liquid chromatography. The same materials as in the separation column were packed in a 0.32 mm i.d. cylindrical flow cell, where the analytes were detected in the presence of the stationary phase. The present detection system greatly improved the sensitivity of the late-eluting analytes, compared with common fluorimetric detection with an empty flow cell. Both peak height and peak area of analytes increased with increasing retention time owing to the focusing and environmental effects of the stationary phase. The detection limit of the analyte eluting in ca. 70 min was improved by a factor of 73 in comparison with that achieved by common fluorimetric detection with an empty flow cell.