Using a PC camera to determine the concentration of nitrite, ammonia nitrogen, sulfide, phosphate, and copper in water

Abstract

To quickly and simply determine the concentration of compounds in water, a simple method based on an ordinary computer camera was proposed, and a device was designed. The measuring device used an LED board as the light source, and the solution image was collected by the camera and transmitted to the computer through a USB port for data processing. The measurement method was based on the color reaction of colored compounds. A camera was used instead of a spectrophotometer for data acquisition, and the color depth of the solution was determined by measuring the color difference from the current material solution to the blank sample solution. Firstly, the solution image was obtained by the camera, and the average RGB value of the central region of the solution image was converted to its corresponding LAB value. Then, the color difference of the value relative to the blank solution was calculated. Finally, the color difference values of a series of standard solutions were obtained, and the corresponding standard curve was obtained by fitting, which was used to measure the unknown concentration of the substance in the solution. The method was successfully applied to the determination of nitrite, ammonia nitrogen, sulfide, and phosphate in water. The results showed that the PC camera permitted the method's simple design and easy operation, and provided a simple method to detect the concentration of substances in water through the application of computer image processing technology and color analysis technology.