FI-Chemiluminescence Determination of Hydrocortisone

A sinuous flow-cell with 200 μm in width, 100 μm in depth and 9 cm in length was carved with laser carving machine on a piece a poly methyl mathacrylate (PMMA, 50 mm×40 mm×3 mm) which was covered and bonded with another piece of PMMA of same size under 1.6 MPa and 108 ℃ to from the micro-flow injection chip. Based on the sensitivation of chemiluminescence (CL) of the reaction system of luminol-K3Fe(CN)6 by hydrocortisone, and by using the micro FI-chip, a method of FI-CL determination of hydrocortisone was proposed. The optimum concentrations of luminol and K3Fe(CN)6 were found to be 8.0×10-5 and 4.0×10-5mol·L-1 respectively, and pH value of the system was found to be 12. Linear relationship between the magnitude of increase in CL intensity and mass concentration of hydrocortisone was obtained in the range of 8.0×10-5-8.0×10-2g·L-1 with detection limit (3S/N) of 4.0×10-5g·L-1. The proposed method was used in the analysis of food sample, giving values of recovery in the range of 96.5%-104.0%.