Abstract

To aid in the evaluation of the potential toxicity of N-nitroso derivatives of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), we describe a pressurized liquid extraction (PLE) followed by liquid chromatography-electrospray ionization-mass spectrometry (LC–ESI-MS) method for determination of RDX and its N-nitroso derivatives: hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) in soils. Sandy loam soil was spiked with RDX and its N-nitroso derivatives (MNX, DNX, and TNX). Acetonitrile was used as the PLE extraction solvent at 100 °C and 1500 psi for 15 min. Florisil was used to cleanup extracts following PLE. Instrumental analysis employed LC–ESI-MS, in which 1 mM acetic acid was added to the mobile phase to facilitate formation of acetate adduct ions [M + CH₃COO]⁻. The method detection limits (MDLs) for RDX, MNX, DNX, and TNX were 1.46, 1.46, 1.69, and 1.93 ng/g, respectively. High recovery (91.1–108.3%), good precision (RSD: 3.2–12.4%), and reproducibility were achieved. This method proved effective and was applied to monitor the reductive biotransformation of MNX in soils with the presence of earthworms (Eisenia fetida).

Keywords: Explosives; RDX; MNX; DNX; TNX; N-Nitroso compounds (NOCs); Liquid chromatography (LC); ElectroSpray ionization (ESI); Mass spectrometry (MS); Pressurized liquid extraction (PLE); Soil

Article Outline

1. Introduction

2. Experimental

2.1. PLE and extract cleanup

2.2. LC–ESI-MS analysis

2.3. Calibration

2.4. Recovery, precision, and method detection limit

2.5. Matrix effects investigation

2.6. Analysis of real samples

3. Results and discussion

4. Conclusions

Acknowledgements

References