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Open AccessArticle

Selective Monitoring of Oxyanion Mixtures by a Flow System with Raman Detection

1
Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Alcalá de Henares, Madrid 28871, Spain
2
University Institute of Research in Police Sciences (IUICP), Law Faculty, University of Alcalá, Alcalá de Henares, Madrid 28871, Spain
3
Department of Electronics, University of Alcalá, Polytechnic School, Alcalá de Henares, Madrid 28871, Spain
*
Author to whom correspondence should be addressed.
Sensors 2018, 18(7), 2196; https://doi.org/10.3390/s18072196
Received: 31 May 2018 / Revised: 29 June 2018 / Accepted: 6 July 2018 / Published: 8 July 2018
(This article belongs to the Special Issue Optical Biochemical Sensor Systems and Applications)
Raman spectroscopy is a selective detection system scarcely applied for the flow analysis of solutions with the aim of detecting several compounds at once without a previous separation step. This work explores the potential of a portable Raman system in a flow system for the selective detection of a mixture of seven oxyanions (carbonate, sulphate, nitrate, phosphate, chlorate, perchlorate, and thiosulphate). The specific bands of these compounds (symmetric stretching Raman active vibrations of carbonate at 1068 cm−1, nitrate at 1049 cm−1, thiosulphate at 998 cm−1, phosphate at 989 cm−1, sulphate at 982 cm−1, perchlorate at 935 cm−1, and chlorate at 932 cm−1) enabled their simultaneous detection in mixtures. Although the oxyanions’ limit of detection (LOD) was rather poor (in the millimolar range), this extremely simple system is very useful for the single-measurement detection of most of the oxyanions in mixtures, without requiring a previous separation step. In addition, quantitative determination of the desired oxyanion can be performed by means of the corresponding calibration line. These are important advantages for controlling in-line processes in industries like those manufacturing fertilizers, pharmaceuticals, chemicals, or food, among others. View Full-Text
Keywords: flow analysis; oxyanions; Raman detection flow analysis; oxyanions; Raman detection
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MDPI and ACS Style

Zapata, F.; Ortega-Ojeda, F.; García-Ruiz, C.; González-Herráez, M. Selective Monitoring of Oxyanion Mixtures by a Flow System with Raman Detection. Sensors 2018, 18, 2196.

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