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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #245841

Title: Disposable nitrate-selective optical sensor based on fluorescent dye

item KIM, GIYOUNG - Rural Development Administration - Korea
item Sudduth, Kenneth - Ken
item GRANT, SHEILA - University Of Missouri
item Kitchen, Newell

Submitted to: Sensor Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2012
Publication Date: 6/29/2012
Citation: Kim, G., Sudduth, K.A., Grant, S.A., Kitchen, N.R. 2012. Disposable nitrate-selective optical sensor based on fluorescent dye. Sensor Letters. 37(3):209-213. DOI: 10.5307/JBE.2012.37.3.209.

Interpretive Summary: The ability to monitor solution nitrate content is important for many applications, including regulating nutrient levels in hydroponic systems and tracking pollutant levels in water bodies. Many currently available nitrate ion sensors are limited in application due to problems such as an inherent tendency for their readings to drift over time. As an alternative, we developed sensors employing a dye that changes its optical properties when exposed to nitrate. Output from the sensor was sensitive to a wide range of nitrate ion levels, and was relatively insensitive to other ions. After additional development, this sensing approach may allow monitoring nitrate levels in a variety of systems. This could benefit producers by allowing them to more accurately control their production practices and the general public through improved methods to monitor environmental nitrate levels.

Technical Abstract: A simple, disposable thin-film optical nitrate sensor was developed. The sensor was fabricated by applying a nitrate-selective polymer membrane on the surface of a thin polyester film. The membrane was composed of polyvinylchloride (PVC), plasticizer, fluorescent dye, and nitrate-selective ionophore. Fluorescence intensity of the sensor, as measured with a commercial flourospectrometer, increased on contact with a nitrate solution. The optical sensor exhibited a linear response over four concentration decades and good selectivity against chloride and sulphate ions. Using this sensor, nitrate ion concentrations in plant nutrient solutions can be determined by direct optical measurements without any pre-conditioning.