A polymethyl-methacrylate (PMMA) acrylic sample cell using flow injection is developed in this research for the determination of nitrite in an aqueous media. The research focuses on exhibiting direct absorbance spectrophotometry of nitrite using concentration of samples ranging from 0.1078 to 1.725 ppm. Nitrite determination is done colorimetrically using the Greiss reagent method. This method is based on the reaction of nitrite with sulphanilamide acid and N-1-napthylamine (NED) utilizing diazo coupling, and a syringe is used to administer the nitrite solution. The sample cell being used possesses a diameter of 1 mm with an overall size of 7.35×22 mm2. To gauge the direct absorbance, a wavelength range from 400 to 650 nm has been selected for the testing, and the maximum absorbance is found to be at 545 nm. The validity of the proposed cell is explained in this letter.