Semicarbazide (SEM), a marker residue used to monitor the use of prohibited drug nitrofurazone (NFZ), is commonly found in wild crustaceans, implying the natural origin. However, the difference between endogenous and exogenous SEM has rarely been investigated. So, tissue-bound SEM was determined in samples collected from giant river prawns cultured in an aquaculture farm and in samples from an experiment where giant river prawns were fed twice a day with NFZ at 30 mg/kg for 5 days. At day 10 of drug withdrawal, muscle SEM of the NFZ-fed prawn was 17.78 ng/g and depleted to 1.18 ng/g at day 90 (half-life 20.31 days) which was significantly higher than the control prawn (usually ≤ 0.1 ng/g). In contrast, the average SEM in the shell was independent of NFZ treatment. SEM was not found in the aquaculture farm samples, implying that the SEM in cultured prawn did not originate from SEM contamination.

中文翻译：

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口服呋喃西林后罗氏沼虾体内氨基脲的消耗动力学及其在水产养殖场中的发生

氨基脲 (SEM) 是一种用于监测违禁药物呋喃西林 (NFZ) 使用情况的标记残留物，常见于野生甲壳类动物中，表明其天然来源。然而，内源性和外源性 SEM 之间的差异很少被研究。因此，对从水产养殖场养殖的大河虾采集的样品以及每天两次用 30 mg/kg NFZ 连续 5 天喂养大河虾的实验样品测定了组织结合 SEM。在停药第 10 天，NFZ 喂养的虾的肌肉 SEM 为 17.78 ng/g，并在第 90 天时降至 1.18 ng/g（半衰期 20.31 天），显着高于对照虾（通常≤ 0.1 ng） /G）。相反，壳中的平均 SEM 与 NFZ 处理无关。水产养殖场样品中未发现SEM，这表明养殖对虾中的SEM并非源自SEM污染。