Rapid, At-Sea Detection of Munition Compounds in Coastal Waters Using a Shipboard System

Abstract

Coastal waters are contaminated globally with millions of metric tons of munitions from the two world wars which constitute a potential threat to ecosystems and humans. Laboratory-based chemical methods for the detection of munition compounds (MCs) in seawater typically take weeks to months between sample collection and analysis. The current work details a novel, field-deployable system for rapid (under 10 min) analysis of four common MCs (1,3-dinitrobenzene (DNB), amino-4,6dinitrotoluene (ADNT), 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)). The system uses a fluidic preconcentration unit with high-performance liquid chromatography (HPLC) and detection by electrospray-ionization mass spectrometry and UV−vis spectroscopy. The fluidic unit comprises two solid-phase extraction (SPE) columns for preconcentration of target MCs from the seawater matrix and allows loading and analysis of two samples simultaneously. Seven SPE resins were tested for extraction efficiency and robustness, with Porapak RDX showing best performance. Chromatographic separation of target MCs was performed using a C8 reversed-phase HPLC column. Limits of detection (LODs) were 3.7, 1.8, 3.6, and 10.7 ng L −1 for DNB, ADNT, TNT, and RDX, respectively. The system's analytical performance and automated data processing procedure were demonstrated in the Baltic Sea.