Use of tris(2,2′-bipyridine)osmium as a photoluminescence-following electron-transfer reagent for postcolumn detection in capillary high-performance liquid chromatography
Use of tris(2,2′-bipyridine)osmium as a photoluminescence-following electron-transfer reagent for postcolumn detection in capillary high-performance liquid chromatography
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DOI：
10.1021/ac051182o
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发表时间：
2006-03-15
影响因子：
7.4
通讯作者：
Weber, SG
中科院分区：
文献类型：
--
作者：
Jung, MC;Munro, N;Weber, SG
我们实验室开发的光致发光跟随电子转移（PFET）技术是一种用于可氧化分析物的灵敏色谱检测方法。由于氧化是均匀的，该技术避免了电极结垢的问题。液相氧化剂与分离后的电化学活性分析物反应，变得能够光致发光。测量激光诱导的光致发光以定量分析物。因此，氧化剂的电化学性质决定了检测选择性，光谱性质决定了灵敏度。本文研究了三（2，2 ′-联吡啶）锇（1）作为PFET系统液相氧化剂的性质。该配合物的氧化还原电位比三（2，2 '-联吡啶）钌（2）的正性小;因此，通过与PbO 2反应在线生成1（3+）以及通过1（3+）选择性氧化邻苯二酚是可能的。当与酸性移动的相混合时，1（3+）的温和氧化能力导致较低的背景信号（与2（3+）相比）。1（2+）的光致发光比2（2+）弱得多;尽管如此，该系统对多巴胺、3-甲氧基酪胺和5-羟色胺的检测限达到了亚纳摩尔。测定注射诺米芬新前后大鼠脑纹状体透析液中多巴胺和3-甲氧基酪胺的含量。移动的相的pH可以控制检测选择性，因为大多数有机物的氧化伴随着质子转移。1与邻苯二酚的反应显示pH依赖性的敏感性，导致pH依赖性的反应速率变化。由于反应速率也是温度依赖性的，因此混合器处的温度升高导致更高的灵敏度。然而，噪声水平在升高的温度下也增加;因此，检测限没有提高。
The photoluminescence-following electron-transfer (PFET) technique, developed in our laboratory, is a sensitive chromatographic detection method for oxidizable analytes. Because the oxidations are homogeneous, the technique avoids the problem of electrode fouling. A liquid-phase oxidant reacts with the electrochemically active analytes after separation, becoming capable of photoluminescence. Laser-induced photoluminescence is measured to quantitate the analytes. Thus, the electrochemical properties of the oxidant determine the detection selectivity, and the spectroscopic properties define the sensitivity. The properties of tris(2,2'-bipyridine)osmium (1) were investigated for use as the liquid-phase oxidant in the PFET system. The redox potential of the complex is less positive than that of tris(2,2'-bipyridine)ruthenium (2); thus, on-line generation of 1(3+) by reaction with PbO2, and selective oxidation of catechols by 1(3+), was possible. The mild oxidizing power of 1(3+) led to a lower background signal (compared to 2(3+)) when mixed with acidic mobile phases. Photoluminescence from 1(2+) was much weaker than that from 2(2+); nonetheless, the system achieved subnanomolar detection limits for dopamine, 3-methoxytyramine, and serotonin. Dopamine and 3-methoxytyramine in rat brain striatal dialysates were determined before and after the injection of nomifensine. The pH of the mobile phase can govern the detection selectivity, since oxidation of most organics is accompanied by proton transfer. Reaction of 1 with catechols showed pH-dependent sensitivity resulting from pH-dependent reaction rate changes. Since the reaction rate is also temperature dependent, increased temperature at the mixer resulted in higher sensitivity. However, the noise level also increased at elevated temperature; thus, the detection limit did not improve.