Application of the luminol chemiluminescence reaction for the determination of nine corticosteroids Original Research Article

A luminol chemiluminescence (CL) reaction was applied for the simultaneous determination of nine corticosteroids (triamcinolone, prednisolone, prednisone, cortisone, betamethasone, dexamethasone, corticosterone, flumethasone and triamcinolone acetonide) using flow injection. The luminol solution was prepared in NaOH with hexacyanoferrate(II) and hexacyanoferrate(III) was used as oxidant. Adequate isocratic chromatographic separation was obtained using a simple mobile phase (acetonitrile–water). The kinetic aspects of CL reactions are very important in the sense that maximum intensity occurs simultaneous to the arrival of the substance in the detector cell. Here we determined the moment at which maximal luminescence is reached for the nine corticosteroids assayed. When optimal experimental conditions were used, the lowest range injected was 15 mg/l for prednisolone, prednisone and cortisone, and the highest was 2 mg/l for betamethasone. Reproducibility ranged from 2.59 to 7.59 and repeatability from 1.50 to 3.61 for the different corticosteroids.