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Open AccessArticle

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

Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Alcalá de Henares, Madrid 28871, Spain
University Institute of Research in Police Sciences (IUICP), Law Faculty, University of Alcalá, Alcalá de Henares, Madrid 28871, Spain
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;
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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