ИСТИНА

Unsymmetrical dimethylhydrazine (1,1-dimethylhydrazine, UDMH) is widely used as a component of rocket fuel. One of the main sources of UDMH in the environment is the spillage of jet fuel in areas of rocket launching and worked stage fall. Being a substance of the first hazard class in Russia, its determination in environmental materials (water, air, and soil) is an important and difficult problem of analytical chemistry [1]. The current tentative permissible level (TPL) of UDMH in household water is 0.06 μg/L [2]. Low value of TPL and its decreasing tendency requires the development of selective and sensitive methods for the determination of UDMH in the environmental water. There are several methods for UDMH determination using various organic compounds as derivative reagents, including carbonyl groups. However, some of these reagents are expensive and specific, reactions with these derivative reagents are carried out under rigid conditions and products of derivatization are unstable [3]. Thereby, in this work we decided to use 4-nitrobenzaldehyde as derivative reagent for determination of UDMH in environmental water, because it provides a single, stable product with quantitative yield in reaction with UDMH (4-nitrobenzaldehyde 1,1-dimethylhydrazone) under mild conditions. Currently, all methods for determination of UDMH at TPL require preconcentration, which leads to increasing the time for sample preparation. Among the available techniques, we decided to determine UDMH using gas chromatography-tandem mass spectrometry (GC-MS/MS) with electron ionization (EI), which obtains high sensitivity and selectivity, delivers accurate quantitative results and confident identification in complex matrices. Also, this method allows easy concentration using liquid-liquid extraction. GC-MS/MS with EI in MRM mode (m/z 193 → m/z 104, 131) using programmed temperature vaporization inlet system with large injection volume (10μL) provided a detection limit of 0.025 μg/L. The reported method provided good sensitivity, recoveries and precision for the analysis of UDMH in environmental water.