On-line electrochemical monitoring of (TNT) 2,4,6-trinitrotoluene in natural waters

Abstract

An electrochemical flow system for on-line monitoring of trace 2,4,6-trinitrotoluene (TNT) in marine environments, based on a square-wave voltammetric operation at a carbon-fiber based detector, is described. The system offers selective measurements of sub-ppm concentrations of TNT in untreated seawater matrix (with a detection limit of 25 ppb). It responds rapidly to sudden changes in the TNT concentration with no observable carry-over. About 600 runs can be made every hour with high reproducibility (e.g. R.S.D.=2.3%, n=40) and stability. A computerized baseline subtraction offers effective compensation of the oxygen background contribution. Good sensitivity and stability is illustrated also for on-line monitoring of TNT in untreated river water samples. The system lends itself to full automation and to deployment onto various mobile platforms. By meeting the high-sensitivity, selectivity, stability, portability and low-cost demands, such as voltammetric flow detection holds great promise for field-based screening operations aimed at characterizing and remediating unexploded ordnance (UXO) contaminated underwater sites.