A portable flow-injection instrument incorporating a miniature spectrometer for the real-time monitoring of nitrate in rivers
✍ Scribed by Simon Coles; Malcolm Nimmo; Paul Worsfold
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 340 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0895-7533
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✦ Synopsis
A field-deployable, flow-injection-based instrument for monitoring nitrate in rivers is described. It incorporates a miniature spectrometer that gives full spectral acquisition (200-700 nm) in real time. This allows the dynamic range to be adjusted in the field to meet local requirements by monitoring at different wavelengths. For pristine environments, a linear range of 0-1 mg L 1מ NO 3 -N (r 2 ס 0.9998, n ס 6) and a detection limit of 0.007 mg L 1 NO 3 -N (based on blank plus 3s) were achieved by monitoring at 597 nm. For impacted environments, a linear range of 0-9 mg L 1מ NO 3 -N (r 2 ס 0.9998, n ס 6) was achieved at 510 nm. Conventional peristaltic pumps were replaced by solenoid-operated, self-priming micropumps, and injection of sample was achieved by a series of electronic switching valves. The pulsations of the micropumps were effectively removed by subtracting the response at a nonabsorbing wavelength (444 nm). Instrument control and data acquisition and processing were done within a graphical programming environment. The monitor was successfully deployed for 3 days at the River Frome in Dorset, United Kingdom.