Abstract

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.

Highlights

  • As a vibrational technique, Raman spectroscopy is widely used for the chemical characterization of substances, either solid or liquid

  • Diluted solutions were prepared for determining the limit of detection (LOD) of each oxyanion

  • The vertical design helped dealing with the different microconvection flow intended measurements

Read more

Summary

Introduction

Raman spectroscopy is widely used for the chemical characterization of substances, either solid or liquid. The applicability of Raman spectroscopy to the flow analysis of aqueous solutions with the aim of simultaneously detecting several analytes has been quite less researched. The simultaneous Raman detection of several oxyanions in flow solutions showed few advances along the years In this respect, nitrate and perchlorate anions were successfully detected in-line using Raman spectroscopy after being separated by capillary electrophoresis [2]. This work focused on setting up a simple flow system with Raman detection for the selective monitoring of oxyanion mixtures of carbonate, sulphate, nitrate, phosphate, chlorate, perchlorate, and thiosulphate and its application for analysing fertilizer solutions containing at least one of the abovementioned oxyanions

Samples
Instrumentation
Flow analysis methodology
Discussion
Average
By comparing again
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call