Gong, Weidong, Mowlem, Matt, Kraft, Michael and Morgan, Hywel
A simple low cost double beam spectrophotometer for colorimetric detection of nitrite in seawater
IEEE Sensors Journal, 9, (7), .
This paper reports on the optical detection system of a prototype nitrite sensor for seawater analysis. The sensor uses a colorimetric Griess reaction that produces an Azo dye with an absorption peak at 540 nm. A simple low-cost double beam spectrophotometer using a green light emitting diode (LED) light source, two integrated photo detectors and lock-in detection is described. A log-ratio amplifier is used to produce an output proportional to absorbance. The optical devices were mounted in a cast resin block to prevent shock and vibration. Experimental results show the detection system has a limit of detection of 0.1 muM.
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