A synthetic procedure has been developed for the preparation of 1,4-diaza-2,3;8,9-dibenzo-7,10-dioxacyclododecane-5,12- dione. A carbon paste electrode based on the new macrocyclic diamide was constructed for Ca2+ determination. The calibration graph was linear over a wide concentration range (1.3 × 10−6–3.2 × 10−3 M) with a near Nernstian slope of 32 mV decade−1. The limit of detection is 7.9 × 10−7 M (0.032 ppm). Selectivity coefficients were tabulated and the working pH range was determined. It has a fast response time of <10 s and can be used for at least 3 months without any considerable divergence in potentials. The electrode was successfully applied to the determination of Ca2+ ions in a pharmaceutical preparation
