Evaluation of a novel hollow fiber membrane technique for collection of 1,1-dimethylhydrazine in air

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.

Development of Membrane Hollow Fiber for Determination of Maleic Anhydride in Ambient Air as a Field Sampler

This research develops a rapid method for sampling and analysis of maleic anhydride (MA) in air using a one-step hollow fiber (HF) membrane in the liquid phase followed by high-performance liquid chromatography. A sampling chamber was prepared for sampling of MA with HF-supported de-ionized water absorbency. Several important parameters, such as sampling flow rate, sampling time, and breakthrough volume (BTV), were optimized at different concentrations using a central composite design. The results showed that sampling could be performed at the maximum period of 4 h with a flow rate of 1 mL min-1 for different concentrations (in the range of 0.05-2 mg m-3). The BTV was 240 mL. The relative standard deviations for the repeatability of interday and intraday were 7-10%, 10%, respectively, and the pooled standard deviation was 0.088. The limit of detection and limit of quantitation values were 0.033 and 0.060 mg m-3, respectively. Moreover, our findings revealed that the samples could be stored in sealed HF flexible plastic tubes in a cover at refrigerator temperature (4°C) for up to 7 days. The HF method was compared with method number 3512 National Institute Occupational Safety and Health for determination of MA. There was a good correlation (R2 = 0.99) between the two methods at a concentration of 0.05 to 2 mg m-3 in the laboratory and the average concentration of MA for both methods was 0.11 mg m-3 in the ambient air at an adhesive manufacturer. Our findings indicated that the proposed HF can act as a reliable, rapid, and effective approach for sampling of MA in workplaces.