A simple, sensitive and selective chemiluminescence method is proposed for the determination of Acetylcysteine and Diclofenac in pharmaceutical samples. The method is based on the measuring light intensity of NaHCO3-H2O2 @ CdS chemiluminescence system in the absence and presence of Acetylcysteine and Diclofenac. It was found that the intensity of chemiluminescence is increased by addition of acetylcysteine while the light intensity is decreased with increasing diclofenac concentration. The CdS quantum dots nanoparticles were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectrophotometry and Fluorescence spectroscopy. The optimum conditions for maximizing the CL emission intensity were studied by means of a Box–Behnken experimental design combined with response surface modeling (RSM) and quadratic programming. Under the optimal conditions, results for measurement of diclofenac was found as follows: linear range 1 × 10−5 - 1 × 10−9 Molar with R2 = 0.98, limit of detection 5 × 10−10 Molar and relative standard deviation of 2.4% for diclofenac; and for N-acetylcysteine was : linear range 1 × 10−6 - 1 × 10−9 Molar, the limit of detection 5 × 10−10 Molar, and the relative standard deviation of 3.4%.
