Back to Search Start Over

Microwave-induced self-ignition: An efficient approach for high purity graphite digestion and multitechnique halogen determination.

Microwave-induced self-ignition: An efficient approach for high purity graphite digestion and multitechnique halogen determination.

Authors :
Cruz SM
Druzian GT
Santos RF
Mesko MF
Duarte FA
Flores EMM
Source :
Analytica chimica acta [Anal Chim Acta] 2022 Mar 22; Vol. 1199, pp. 339569. Date of Electronic Publication: 2022 Feb 04.
Publication Year :
2022

Abstract

In this work, high purity graphite, a high chemically stable material, was effectively digested using a single method allowing compatible solutions for the further multitechnique determination of halogens by: ion chromatography (F and Cl), inductively coupled plasma mass spectrometry (Cl, Br and I) and by ion selective electrode (only for F). The recent system using microwave-induced self-ignition (MISI) is based on the strong interaction between microwave radiation and graphite in a closed system pressurized with oxygen (Maxwell-Wagner effect). Carbon-based materials present intense and specific interfacial polarization when exposed to microwave electromagnetic field resulting in a fast heating rate. This effect associated to a pressurized oxygen system, provides a quick self-ignition of carbon-based materials and consequent combustion/digestion of organic matrices. Under optimized conditions, sample masses up to 600 mg were fully digested in a quartz vessel under 20 bar of oxygen pressure and using just a diluted solution (100 mmol L <superscript>-1</superscript>  NH <subscript>4</subscript> OH) for the quantitative absorption of all the analytes. MISI method was validated, and the accuracy (better than 94%) was evaluated by comparison of results obtained by pyrohydrolysis for two coal certified reference materials as well as with subsequent analytes determination by the three techniques: IC, ICP-MS and ISE. It is important to point out that no filter paper disks, electrical connections or other ignition aids are required as in the case of previous or classical combustion methods. Moreover, just a diluted absorbing solution was used resulting in negligible blanks and relatively low limits of detection. The digestion efficiency was higher than 99%, making the proposed method a suitable and powerful alternative for the quasi complete digestion of graphite and determination of halogens virtually free of interferences.<br />Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.<br /> (Copyright © 2022 Elsevier B.V. All rights reserved.)

Details

Language :
English
ISSN :
1873-4324
Volume :
1199
Database :
MEDLINE
Journal :
Analytica chimica acta
Publication Type :
Academic Journal
Accession number :
35227390
Full Text :
https://doi.org/10.1016/j.aca.2022.339569