Eliciting electromagnetic radiation from a chemical reaction without using any external excitation source, such as light sound, heating or even mechanical force, is called chemiluminescence (CL) [1]. This phenomenon can be catalyzed by several substances such as metal ions, enzymes and nanomartials, among others. In this study, we report that CuO NPs are capable of catalyzing week CL reaction of HCO3 -–H2O2. The CuO NPs were prepared by using quick precipitation technique [2]. The synthesized CuO NPs were characterized by exploiting Xray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dynamic light scattering (DLS) analysis. Furthermore, it was found that atorvastatin has inhibitory effect on the HCO3 -–H2O2 – CuO NPs CL system. Atorvastatin is in a group of drugs called HMG CoA reductase inhibitors, or "statins." It is interesting atorvastatin reduces levels of "bad" cholesterol (low-density lipoprotein, or LDL) and triglycerides in the blood, while increasing levels of "good" cholesterol (high-density lipoprotein, or HDL). Atorvastatin is used to treat high cholesterol, and to lower the risk of stroke, heart attack, or other heart complications in people with type 2 diabetes, coronary heart disease, or other risk factors. Based on the inhibitory effect on this drug, a new approach were suggested for determination of atorvastatin. To this sense, the CL reaction of HCO3-– H2O2 – CuO NPs was optimized to achieve highest CL intensity. Then, under the optimum conditions, the calibration plot for atorvastatin was plotted in the concentration range from 1.3 × 10-7 to 1.0 × 10-4 mol/L. The limit of detection of the CL method was 1.3 × 10-8 mol/L and the relative standard deviation (RSD) for 11 replicate determination of 10-5 mol/L atorvastatin was 4.0 %. The study of the effect of foreign species on the CL system revealed that the CL system possessed good selectivity. In addition, the applicability of the CL method for rea
