Franke Karsten, Patt Jörg T, Kupsch Hermann, Warwick Peter
Institute of Interdisciplinary Isotope Research, Permoserstrasse 15, 04318 Leipzig, Germany.
Environ Sci Technol. 2008 Jun 1;42(11):4083-7. doi: 10.1021/es702671v.
A new method is described for radiolabeling humic substances (HS) with iodine radioisotopes. The method radiolabels the electron-rich aromatic moieties of HS with the 3-[125I]iodobenzenediazonium ion via azocoupling. The method uses four steps: (i) 3-aminobenzenetrimethylstannane is synthesized and isolated by using a silica gel column, (ii) 3-[125I]iodoaniline is synthesized and isolated by HPLC, with radiochemical yields of up to 60%, (iii) 3-[125I]iodobenzenediazonium chloride is synthesized, and the reaction mixture from this step is used in step iv to radioiodinate HS with radiochemical yields of up to 95% (with reference to 3-[125I]iodoaniline). The advantage of this method is that it is selective radiolabeling, placing the radiolabel in a specific site (the 3-position of the phenyl ring) within HS molecules, which minimizes unwanted secondary chemical interactions. Investigations of the stability of the radiolabel and the effect of photoreductive dehalogenation showed that there was a negligible release of 125I. The production of radiolabeled HS using this method allows the sensitive detection of HS in laboratory and field studies. In addition, the method offers the possibility of using different iodine radioisotopes simultaneously in investigations using HS.
描述了一种用碘放射性同位素对腐殖质（HS）进行放射性标记的新方法。该方法通过偶氮偶联用3-[¹²⁵I]碘苯重氮离子对HS中富含电子的芳香部分进行放射性标记。该方法包括四个步骤：（i）使用硅胶柱合成并分离3-氨基苯三甲基锡，（ii）通过高效液相色谱法合成并分离3-[¹²⁵I]碘苯胺，放射化学产率高达60%，（iii）合成3-[¹²⁵I]碘苯重氮氯化物，此步骤的反应混合物用于步骤iv中对HS进行放射性碘化，放射化学产率高达95%（相对于3-[¹²⁵I]碘苯胺）。该方法的优点是它是选择性放射性标记，将放射性标记置于HS分子内的特定位置（苯环的3-位），从而使不需要的二次化学相互作用最小化。对放射性标记稳定性和光还原脱卤作用的研究表明，¹²⁵I的释放量可忽略不计。使用该方法生产放射性标记的HS能够在实验室和现场研究中灵敏地检测HS。此外，该方法还提供了在使用HS的研究中同时使用不同碘放射性同位素的可能性。
