Unsymmetrical dimethylhydrazine (UDMH) based rocket fuel, when released into the soil, undergoes oxidative transformations to form a variety of toxic nitrogen‐containing products (TPs). Loamy soils containing aluminosilicates (clay) are capable of strong binding and retention of UDMH TPs due to a combination of polar sorption and cation‐exchange properties, posing challenges for their extraction and quantification. To overcome this problem, the present study proposes direct thermal desorption (TD) of analytes from loam facilitated by the addition of modifiers competing with UDMH TPs for sorption centers and ensuring their conversion into molecular form. Among tested additives, the mixture of potassium chloride and hydroxide demonstrated the best performance and provided recoveries of the most UDMH TPs exceeding 70% under optimized TD conditions (200°C, 30 min). The online combination of TD with gas chromatography‐tandem mass spectrometry allowed for the development of a method for the determination of 15 UDMH TPs in loamy soils with limits of detection in the range of 0.2–15 µg/kg. The use of matrix‐matched calibration and deuterated internal standards ensured high accuracy (80%–100%) and precision (relative standard deviation < 18%) of the analysis. The developed method was validated and successfully tested in the analyses of real loamy soil samples polluted with rocket fuel.

中文翻译：

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热解吸气相色谱-串联质谱法分析壤土中含氮火箭燃料转化产物


以不对称二甲肼 (UDMH) 为基础的火箭燃料在释放到土壤中时会发生氧化转化，形成各种有毒的含氮产物 (TP)。由于极性吸附和阳离子交换特性的结合，含有硅铝酸盐（粘土）的壤土能够强烈结合和保留 UDMH TP，这给它们的提取和定量带来了挑战。为了克服这个问题，本研究提出通过添加与 UDMH TP 竞争吸附中心的改性剂来促进壤土中分析物的直接热解吸 (TD)，并确保它们转化为分子形式。在测试的添加剂中，氯化钾和氢氧化钾的混合物表现出最佳性能，并且在优化的 TD 条件（200°C，30 分钟）下，大多数 UDMH TP 的回收率超过 70%。 TD 与气相色谱-串联质谱法的在线组合允许开发一种测定壤土中 15 种 UDMH TP 的方法，检测限在 0.2–15 µg/kg 范围内。使用基质匹配校准和氘代内标确保了分析的高精度 (80%–100%) 和精密度（相对标准偏差 < 18%）。所开发的方法在被火箭燃料污染的真实壤土样品的分析中得到了验证并成功进行了测试。