A concentration detection limit of 100 fM was achieved for the fluorescein ion by improving the experimental setup used for Hadamard transform capillary electrophoresis. Two argon-ion lasers, a gating laser for sample injection and a probe laser for the excitation of analyte molecules, were employed for the efficient photodegradation of analyte molecules in laser-induced fluorescence detection using an optically gated sample-injection method. In addition, a dichroic mirror, located in the pathway of the probe laser was used to exclude the other lines of the argon-ion laser. Using a Hadamard matrix on the order of 2046, the concentration limit of detection for fluorescein ion was determined to be 100 fM at S/N = 3, in which the average number of molecules in a single injection volume was calculated to be 27. The influences of the output power in both the gating and probe lasers on the sensitivity are also discussed.
ASJC Scopus subject areas
- Analytical Chemistry