Quantification of paramagnetic ions in solution using time domain NMR. PROS and CONS to optical emission spectrometry method

Author(s)

Kock, Flavio V. C. ^[1] ; Machado, Maiara P. ^[2] ; Athayde, Geisamanda P. B. ^[2] ; Colnago, Luiz A. ^[3] ; Barbosa, Lucio L. ^[4]

Affiliation

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, Ave Trabalhador Sao Carlense 400, BR-13566590 Sao Carlos, SP - Brazil

^[2] Univ Fed Espirito Santo, Lab Pesquisa & Desenvolvimento Metodol Anal Petr, Av Fernando Ferrari 514, BR-29075910 Vitoria, ES - Brazil

^[3] Embrapa Instrumentacao, Rua 15 Novembro 1452, BR-13560970 Sao Carlos, SP - Brazil

^[4] Univ Fed Sao Paulo, Rua Carvalho de Mendonca 144, BR-11070010 Santos, SP - Brazil

• Document type: Journal article
• Source: Microchemical Journal; v. 137, p. 204-207, MAR 2018.
• Web of Science Citations: 2

Abstract

Solutions containing paramagnetic ions (PMIs) have been widely used in several industrial and agricultural applications. Although the concentrations of these ions in solutions are very important, they are rarely checked due to the high cost of the measurements. In this paper, we demonstrate the viability of 2 MHz time-domain nuclear magnetic resonance (TD-NMR) relaxometer to quantify PMIs in solution. The method was used to quantify the concentration of Co2+, Cr3+, Cu2+, Fe3+ and Mn2+ and is based on linear correlation between the transverse relaxation rate (T-2(-1)) of the hydrogens of water and PMIs concentration. The method was validated using inductively coupled plasma optical emission spectrometry (ICP-OES), which is the standard method for quantitative elemental analyses. The concentration of PMIs were analyzed between 0.5 and 10 mg.L-1, with r(2) >= 0.99 between the two methods. Although the limits of detection (LOD) and quantification (LOQ) of TD-NMR are several orders of magnitude higher than those of ICP-OES, they are in the range of concentration normally found in commercial applications. Therefore, this work demonstrate that TD-NMR can be an affordable alternative for certificate the concentration of PMIs concentration in small laboratory in industrial or agricultural facilities. (C) 2017 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 17/12864-0 - Effect of NMR magnetic field in chemical reactions monitored NMR in situ
• Grantee: Luiz Alberto Colnago
• Support Opportunities: Regular Research Grants
• FAPESP's process: 12/23169-8 - In situ study of action of quitosan biopolymer in the decontamination of metals and herbicides in aqueous system by electrochemistry coupled to high and low field NMR
• Grantee: Flavio Vinicius Crizostomo Kock
• Support Opportunities: Scholarships in Brazil - Doctorate