Chemical oxygen demand (COD) is a synthetic indicator that represents the degree of organic pollution in water. Compared with the conventional wet chemical method, near-infrared (NIR) transmission and ultraviolet (UV) absorbance method based on photoelectric detection technology and spectroscopy analysis offer advantages such as high precision, speed, non-contact, and absence of secondary pollution, to name a few. NIR transmission spectra and UV absorbance spectra of standard solution configured