利用薄層層析進行半胱胺酸與過鎝酸根錯化合的研究

The Study on the Complexation of Pertechnetate with Cysteine by Thin Layer Chromatography

10.6623/chem.1992011

王愛義(Ai-Yih Wang)；林俊良(Jiunn-Liang Lin)；羅俊光(Jiunn-Guang La)；蔡瑞燦(Zei-Tsan Tsai)

化學

50卷2期（1992 / 06 / 01）

113 - 124

繁體中文

本實驗之目的為選擇不同的配位子濃度（22.4~545 mM的半胱胺酸cysteine），還原劑濃度（氯化亞錫，3.75 mM~26.5 mM）及pH值（pH= 2~8）利用薄層層析的方法進行鎝錯化合的研究。結果發現氯化亞錫可將七價鎝[Tc (VII)]還原為較低價的鎝[Tc(V)]，再與半胱胺酸形成錯化合物。五價的鎝會進行自身氧化還原反應，形成四價的鎝[3Tc(V)→Tc(VII)+2Tc(IV)]，故隨反應時間的增長會有紅色的或綠色的Tc(IV)錯化合物產生。在固定氯化亞錫濃度(7.5 mM)和pH值(pH = 6.5)條件下，錯化合物的產生速率，會隨配位子濃度增加而增快（545 mM半胱胺酸在短時間內即轉變為黃棕色），此乃半胱胺酸亦可扮演還原劑的角色將Tc(VII)迅速還原為Tc(V)，且從黃色轉變為綠色和紅色的時間較快。當半胱胺酸的濃度為400 mM時，如果還原劑濃度太高或pH值太低，則不會有黃色的鎝錯化合物產生而直接形成紅棕色的錯化物，經過一段時間後紅棕色的錯化合物會轉變為綠色。從實驗中亦可得到在固定過鎝酸根濃度下（12.5mM），半胱胺酸濃度愈高在短時間即可得到高的標幟效率，半胱胺酸濃度較低者貝需要經過很長的時間才會得到較高的標幟效率。當半胱胺酸濃度低時（尤其是半胱胺酸濃度為22.4 mM）黃色錯化合物為主要的標幟產物。在反應條件為400 mM cysteine, 7.5 mM SnCl_2，99^TcO_4^-和pH= 8時，在10分鐘標幟效率可以達到99%以上。

The labelling of cysteine with (99)^TcO_4^- and (99m)^TcO_4^- in different cysteine concentration, reductant and pH value was studied by thin layer chromatography in this report. In the present of stannous chloride and cysteine the pertechnetate was firstly reduced to its lower oxidation state and complexed with cysteine. The yellow complex (λ_(max) = 420 nm) was formed in the initial stage and then gradually changed to the red one (λ_(max)= 540 urn) and green one (λ_(max)= 645 nm) during the reaction proceeding. Both of the complexation rate and the labelling yield increased with increasing of cysteine concentration at constant reductant concentration and pH values. The stannous chloride, pertechnetate, pH value and the reaction time not only majority factors to effect the labelling yield but also effect the complex species. The pentavalent technetium complex (yellow) is the dominant species in the lower cysteine concentration (especially at 22.4 mM). When the cysteine concentration is higher enough or the reaction time is much longer, the quadrivalent technetium complexes (red and green) become more preponderant. The label yield was calculated by double strip method, it was higher than 99% in the condition of 400 mM cysteine, 7.5 mM stannous chloride and 12.5 mM pertechnetate at pH 8 within 10 minutes reaction.