Amoxicillin is a penicillin antibiotic that used to cure bacterial infections in sinuses and the respiratory tract and healing of many different types of dermal and renal infections. They are also used in treating some sexually transmitted diseases. Determination of amoxicillin is very important in the quality control of antibiotic preparations in the pharmaceutical industries [1]. Generally, chemiluminescence (CL) is the generation of electromagnetic radiation through an exothermic chemical reaction. Indeed, it is a favourable detection tool owing to its wide dynamic linear range, high sensitivity, low-cost and simple instrumentation [2]. Several chemiluminescence (CL) systems including luminol–periodate [3], luminol–permanganate [4] and luminol–K3Fe(CN)6 [5] and thiosemicarbazide–H2O2 [1], among others have been developed for the determination of amoxicillin. In this research work, Fe3O4 nanoparticles (NPs) were synthesized by using a quick precipitation method and then characterized by using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM) techniques. The characterization study revealed that Fe3O4 NPs were spherical in shape and have a narrow size distribution of about 20–40 nm. It was found that the Fe3O4 NPs enhanced the NaHCO3–H2O2 CL reaction. Moreover, it was revealed that amoxicillin inhibited the Fe3O4 NPs–NaHCO3–H2O2 system. The CL intensity was inversely proportional to the concentration of amoxicillin. Based on theses results, Fe3O4 NPs–NaHCO3–H2O2 system was used for the developing a new, sensitive, simple and green CL analytical method for amoxicillin. The linear dynamic range, limit of detection and relative standard deviation (RSD%) of the method were 3.0 × 10-6 – 1.0 × 10- 3 mol L-1, 2.9 × 10-6 mol L-1 and 2.41, respectively. The CL method was successfully used for the determination of VRP in pharmaceutical formulations. In addition, the possible mechanism of the Fe3O4 NPs–NaHCO3–H2O2 CL reaction was
