Critical absorption limit of nitrate and optimizing estimation methodology for soil solutions and extracts using UV-VIS spectroscopy

Absorption behavior of nitrate and estimation methodology has been studied using different types of samples and UV wavelengths in order to optimize the use of samples and wavelengths to ensure better results. Absorption was highest in 190–310 nm range scanning compared to the single wavelength (210) or combination wavelengths (210+301 nm). Linearity in absorption was up to 40 μg/ml nitrate nitrogen in case of 190–310 nm scan. The wavelengths identified for nitrate in soil leachate samples for maximum absorption was combination of 210+301 nm wavelengths, whereas, wavelength scan from 190 to 310 nm was found better for soil extracts and nutrient solutions. Molar absorption coefficient was highest in case of 190–310 nm wavelength scan region for aqueous solutions. The critical absorption value of nitrate was found as 3.35 at different treatment wavelengths. Using these combination of treatment wavelengths to suitable sample types could yield better absorption results and with a little cost under laboratory conditions.