Use of a sheath flow cuvette for chemiluminescence detection of isoluminol thiocarbamyl‐amino acids separated by capillary electrophoresis

A post‐column reactor was designed for chemiluminescence detection in the capillary electrophoresis separation of isoluminol thiocarbamyl derivatives of amino acids. This system was characterized with respect to hydrogen peroxide concentration and flow rate, surfactant concentration, microperoxidase concentration, and mixing distance. A linear calibration curve (R >0.999) was constructed for isoluminol ranging from at least 30 femtomoles to the detection limit of 40 attomoles injected; the dynamic range of the instrument is at least three orders of magnitude. Detection limit for the isoluminol thiocarbamyl derivative of valine was 500 attomoles. The theoretical plate counts for the raw data are typically 1 × 10 5 for labeled amino acids, and a factor of two better for isoluminol.