BackgroundTrimethylamine (TMA) is a marker used for monitoring the quality of seafood because it is the primary component of the “fishy” odor.MethodsThe levels of TMA in seafood samples were directly measured by helium-plasma ionization mass spectrometry (HePI-MS). Each sample was directly exposed to the HePI source, and the intensity of the m/z 60 signal for protonated TMA was monitored by a selected-ion-recording (SIR) protocol. Using a set of TMA-spiked water standards, the TMA levels in seafood samples were quantified.ResultsThe signal intensity of the m/z 60 ion from shrimp samples maintained at room temperature for 2 days can be attenuated to baseline levels by adding lime juice. The amounts of TMA in samples of salmon and shrimp recovered from some sushi preparations, and in squid samples, were found to be 0.24 μg, 0.16 μg, and 17.2 μg per gram, respectively.ConclusionsHePI-MS is an efficient technique to screen and monitor the TMA content and assess the quality of seafood.

中文翻译：

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通过使用氦等离子体电离质谱 (HePI-MS) 测量三甲胺 (TMA) 水平来筛选海鲜的新鲜度

背景三甲胺（TMA）是用于监测海鲜质量的标志物，因为它是“鱼腥味”的主要成分。方法通过氦等离子体电离质谱（HePI-MS）直接测量海鲜样品中的TMA水平。每个样品都直接暴露于 HePI 源，质子化 TMA 的 m/z 60 信号强度通过选择离子记录 (SIR) 协议进行监测。使用一组 TMA 加标水标准，对海鲜样品中的 TMA 水平进行量化。结果 虾样品的 m/z 60 离子的信号强度可以通过添加酸橙汁在室温下保持 2 天减弱至基线水平。从一些寿司制品中回收的鲑鱼和虾样品以及鱿鱼样品中的 TMA 含量分别为 0.24 μg、0.16 μg 和 17。