Direct quantification of 1,1-dimethylhydrazine transformation products in sandy soil by thermal desorption gas chromatography – Tandem mass spectrometry

The use of rocket propellants based on unsymmetrical dimethylhydrazine (UDMH) in launch vehicles and boosters poses a threat to the environment due to the release of UDMH into soils and its subsequent transformation into a variety of nitrogen-containing compounds, including toxic and carcinogenic ones. The present proof-of-concept study proposes a novel approach to screening and simultaneous determination of a wide range of nitrogen-containing UDMH transformation products in soils, based on direct thermal desorption (TD) as a solvent-free sample extraction technique coupled with GC–MS/MS analysis. Optimal TD conditions consisting of the incubation of 5 mg sample at 300 °C for 30 min, allowed attaining high recoveries (80–100 %) for the most tested compounds and developing the method for quantification of fifteen acyclic and heterocyclic UDMH transformation products in sandy soil with LODs of 0.3–7.8 µg kg−1. The matrix matched calibration and introduction of the internal standard (pyridine‑d5) ensured high accuracy (75–100 %) and precision (RSD < 15 %) of the analysis. Along with high sensitivity and accuracy, the main advantages of the developed method are exceptional simplicity of sample preparation, low amount of toxic sample, high automation degree, and environmental friendliness. The developed method was successfully tested in the analysis of seven real soil samples taken from the Baikonur cosmodrome operational zone (Kazakhstan). The use of TD-GC–MS analysis in full spectrum scanning mode allowed for tentative identification of 62 UDMH transformation products including several compounds not yet described in the literature.