Stepwise injection spectrophotometric determination of epinephrine

Simple, rapid and fully automated methods for the manual and automated spectrophotometric determination of epinephrine have been developed by using schemes of stepwise injection (SWIA) and sequential injection analysis (SIA) implemented in the same manifold. The determination is based on the formation of reduced form of 18-molybdodiphosphate heteropoly anion by its reaction with epinephrine. Using of the reaction vessel in the general SWIA configuration instead of a holding and reaction coil in the SIA manifold provides several essential advantages, including higher sensitivity and lower reagent consumption. The linear dependence of the analytical signal on the epinephrine concentration was preserved over the range of 1.5–30, 3.0–30, and 1.5–25 μmol L −1 by using of SWIA, SIA and spectrophotometric analysis, respectively. The relative standard deviation for the SWIA determination of 10 μmol L −1 epinephrine was 1.8% ( n =10).