Rapid detection of TNT in aqueous media by selective label free surface enhanced Raman spectroscopy

Arniza K M Jamil; Emad L Izake; Arumugam Sivanesan; Peter M Fredericks

doi:10.1016/j.talanta.2014.12.022

Rapid detection of TNT in aqueous media by selective label free surface enhanced Raman spectroscopy

Talanta. 2015 Mar:134:732-738. doi: 10.1016/j.talanta.2014.12.022. Epub 2014 Dec 29.

Authors

Arniza K M Jamil¹, Emad L Izake², Arumugam Sivanesan¹, Peter M Fredericks¹

Affiliations

¹ Nanotechnology and Molecular Sciences Discipline, Faculty of Science and Engineering, Queensland University of Technology, 2 George St., Brisbane 4001, QLD, Australia.
² Nanotechnology and Molecular Sciences Discipline, Faculty of Science and Engineering, Queensland University of Technology, 2 George St., Brisbane 4001, QLD, Australia. Electronic address: e.kiriakous@qut.edu.au.

PMID: 25618729
DOI: 10.1016/j.talanta.2014.12.022

Abstract

We report rapid and ultra-sensitive detection system for 2,4,6-trinitrotoluene (TNT) using unmodified gold nanoparticles and surface-enhanced Raman spectroscopy (SERS). First, Meisenheimer complex has been formed in aqueous solution between TNT and cysteamine in less than 15 min of mixing. The complex formation is confirmed by the development of a pink colour and a new UV-vis absorption band around 520 nm. Second, the developed Meisenheimer complex is spontaneously self-assembled onto unmodified gold nanoparticles through a stable Au-S bond between the cysteamine moiety and the gold surface. The developed mono layer of cysteamine-TNT is then screened by SERS to detect and quantify TNT. Our experimental results demonstrate that the SERS-based assay provide an ultra-sensitive approach for the detection of TNT down to 22.7 ng/L. The unambiguous fingerprint identification of TNT by SERS represents a key advantage for our proposed method. The new method provides high selectivity towards TNT over 2,4 DNT and picric acid. Therefore it satisfies the practical requirements for the rapid screening of TNT in real life samples where the interim 24-h average allowable concentration of TNT in waste water is 0.04 mg/L.

Keywords: 2,4,6-Trinitrotoluene; 2,4-DNT; Label-free SERS; Meisenheimer complex; Picric acid; Ultra trace analysis.