Method development for the determination of 1,1-dimethylhydrazine by the high-performance liquid chromatography-mass spectrometry technique

Unsymmetrical dimethylhydrazine and related compounds in the environment: Recent updates on pretreatment, analysis, and removal techniques

Unsymmetrical dimethylhydrazine (1,1-Dimethylhydrazine, UDMH) has been widely used as aerospace fuel in many countries. The launch of space vehicles can cause the release and leakage of UDMH into the environment, posing serious threats to ecology system and human population. Even worse, the health risks are also pertinent to its numerous classes of transformation products including N-Nitrosodimethylamine (NDMA), because most of them display carcinogenic and mutagenic properties. Recently, there has been an intense ongoing development of simple, fast, green, and effective techniques for determining and removing these hazardous substances. This review summarizes the latest research progress regarding the sources, fates, pretreatment, analysis, and removal techniques of UDMH and related products in the environment. Sample preparation methods mainly include pressurized liquid extraction, liquid-phase microextraction techniques, solid-phase extraction, headspace-solid-phase microextraction, and supercritical fluid extraction. Detection and identification methods mainly include high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), gas chromatography coupled with tandem mass spectrometry (GC-MS/MS), and sensors. Removal methods mainly include advanced oxidation processes, adsorption, biodegradation techniques. The advantages/disadvantages, applications, and trends of the proposed approaches are thoroughly discussed to provide a valuable reference for further studies.

A novel simple and sensitive approach for determination of 1,1-dimethylhydrazine in aqueous samples by high performance liquid chromatography with ultraviolet and tandem mass spectrometric detection after derivatization with unsubstituted aromatic aldehydes

In this work, simple, rapid and highly sensitive method of hazardous chemical 1,1-dimethylhydrazine (unsymmetrical dimethylhydrazine, UDMH) determination based on pre-column derivatization with unsubstituted aromatic aldehydes and reversed-phase high performance liquid chromatography-ultraviolet-tandem mass spectrometry (RP HPLC-UV-MS/MS) has been developed. Along with benzaldehyde, commercially available aromatic aldehydes, namely: 2-naphthaldehyde, 2-pyridinecarboxaldehyde, and 2-quinolinecarboxaldehyde, were used as derivatizing reagents in the analysis of hydrazines for the first time. The reactions were studied in a wide pH range by varying reaction time and other conditions. A slightly alkaline pH 9 was shown to be optimal for the derivatization of UDMH by aromatic aldehydes. The quantitative yield of derivatization products under the established conditions was confirmed by HPLC analysis with amperometric detection. For all studied reagents, wide linear ranges of concentrations (0.01-1000 μg/L) in natural water samples were observed. The limits of detection for UDMH in natural water were in the 3.7-130 ng/L range. 2-Quinolinecarboxaldehyde was selected as the most appropriate reagent for HPLC-UV-MS/MS determination of UDMH. In case of using this reagent, the accuracy was in the range of 97-102%, and precision, expressed as RSD was less than 8%. The developed approach does not require laborious stages of pre-concentration and isolation of UDMH from natural water components.