The Orthogonal Reference Method for In-Situ Analysis of Ammonia Nitrogen Content in Seawater

ABSTRACT Ma, R.; Xie, Z.-X.; Zhang, S.-W.; Chu, D.-Z.; Cao, X.; Wu, N., and Liu, Y.,2018. The orthogonal reference method for in-situ analysis of ammonia nitrogen content in seawater. In: Wang, D. and Guido-Aldana, P.A. (eds.), Select Proceedings from the 3rd International Conference on Water Resource and Environment (WRE2017). Journal of Coastal Research, Special Issue No. 84, pp. 36–43. Coconut Creek (Florida), ISSN 0749-0208. A novel orthogonal reference method of ammonia nitrogen in-situ analysis in seawater is proposed. The method is based on the joint application of “water + reagent” blending device and constant-temperature heating device, which enhances the reaction rate of chromogenic agent and water samples. Water samples and ortho-phthalaldehyde (OPA) are fully mixed and heated in the circulation system up to 40°C by the constant temperature heating device. Next, the above mixture is injected into a flow pool, and fluorescence (400 nm to 480 nm) is excited by a 360 nm LED. Two photodiodes of the...