Vol. 9, Issue 6, Part D (2023)

Ammonia has wide range of applications globally, with maximum use as a fertilizer in agriculture and aquaculture. However, concentration of ammonia above a certain threshold becomes toxic to aquatic fauna. Therefore, the right and accurate quantification of ammonium is important for checking water quality. Colorimetric, high pressure liquid chromatography and ion chromatography are widely used methods for ammonium estimation in water and wastewater samples. Because of cost effectiveness, the colorimetric method is most preferred among all these. However, the colorimetric method is not suitable for marine samples due to the presence of interfering agents such as salts, ions, metals, and biological contaminations. In this study, salicylate method was optimized and validated for ammonium estimation in standard and test samples (marine). In the study, 653 nm wavelength was selected to measure the absorbance and the method was found linear till 70 ppm ammonia concentration. Using this method 100% ammonium was accurately estimated from standard and test samples. The repeatability study conducted with 10 replicates showed that, the method was more precise and less prone to errors. The ruggedness study conducted with different analysts and days showed that the results were more consistent with less variations. Also, the variation in wavelength (±10nm), reagent’s volume (±100 µl) and incubation time (±10 min) did not affect the results significantly and method was found more robust. The validated method has a limit of detection of 0.5 ppm ammonium; hence it can be applied to measure such lower concentrations in marine water. Overall, study clearly shows that the developed salicylic acid method is more specific, linear, accurate, repeatable, rugged, robust and more sensitive for ammonium estimation in marine aquaculture samples.