Analytical Possibilities of Digital Colorimetry. Determination of Nitrite Ion Using Polyurethane Foam
By the example of determination of nitrite as polymeric azodye, the possibility of using office scanner, digital camera and computer data processing in different colorimetric coordinates systems (RGB, CMYK, LAB and HSV) has been studied. The polymeric azodye was obtained by azocoupling reaction between diazotized polyurethane foam (PUF) with 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline. The analytically important colorimetric coordinates in these systems have been revealed and compared, the coordinates resulting in maximum sensitivity of nitrite determination have been chosen. It has been shown that calibration curves of the colorimetric coordinates versus concentration of nitrite in aqueous solution can be described by first order exponent. Detection limits of the determination of nitrite using scanner and digital camera are comparable. The least detection limits of nitrite (1 - 3 ng mL-1) are achieved in RGB and CMYK colorimetric systems.