Simultaneous determination of unsymmetrical dimethylhydrazine and methylhydrazine in aqueous samples via in situ derivatisation and HS-SPME-GC‒MS/MS

Unsymmetrical dimethylhydrazine (UDMH) and methylhydrazine (MH) are widely used as rocket propellants and pose significant environmental and health risks associated with their high toxicity. Their accurate quantification in water is crucial for environmental monitoring of space rocket activities and requires selective and sensitive analytical methodology compatible with aqueous matrices. The present study introduces a simple, rapid and robust GC-MS/MS method for the simultaneous determination of UDMH and MH in tap water, river water, and thawed snow, based on in situ derivatisation with pentanal and headspace solid-phase microextraction (HS-SPME) as a sample preparation technique. The HS-SPME conditions were optimised to maximise sensitivity and precision. The best performance was achieved with a PDMS/DVB (polydimethylsiloxane/divinylbenzene) fibre at 50°C, 30 min extraction time, and a sample pH adjusted to ≥7. The limits of quantification achieved (0.07 and 0.03 μg L−1 for UDMH and MH, respectively) meet the stringent quality standards established for fishery reservoirs and even drinking water. The developed method is distinguished by the minimum amounts of reagents required and avoiding manual sample preparation steps complying the principles of green analytical chemistry. It was successfully validated on real matrices and applied to study of the UDMH and MH degradation dynamics of in aquatic systems.