Ultratrace Analysis Using Semiconductor Laser as an Exciting Source

半导体激光器体积小、强度大、价格便宜，而且易于操作。然后，我们开发了一种利用这种半导体激光器进行痕量分析的分析方法。基于半导体激光荧光法的高效液相色谱：我们研制了一种由熔融石英毛细管和光纤组成的微流池。对近红外荧光染料的检出限为12 fg （fg = <10^(-15)> g）。样品经高效液相色谱分离后，采用半导体激光荧光法检测近红外染料。检出限为0.3 pg。用吲哚菁绿标记人血清中的蛋白，用高效液相色谱法分离。该方法可检出白蛋白1.3 pmol。为了测量生物分子，我们开发了一种基于近红外荧光法和酶反应的分析方法。发现吲哚菁绿的荧光强度随<H_2> <O_2>浓度的增加而降低。然后，我们可以测量黄嘌呤存在时黄嘌呤氧化酶的活性。我们可以在0-1单元之间构造一条解析曲线。利用光纤热透镜分光光度法：在近红外区观察到由于泛音振动引起的吸收带。我们利用几根光纤开发了热透镜分光光度法。使用多模光纤的方法具有良好的耦合效率，但输出光束轮廓很差，导致聚焦性能差。因此，它不适合灵敏的检测。另一方面，使用单模光纤的方法具有良好的空间分布，其灵敏度是传统吸收光谱法的50倍左右。

A semiconductor laser is small, intense, less expensive, and can be easily operated. Then, we developed an analytical method using this semiconductor laser for trace analysis.1. High-performance liquid chromatography (HPLC) based on semiconductor laser fluorimetry: We developed a micro-flow cell, consisting of a fused silica capillary and an optical fiber. The detection limit obtained was 12 fg (fg = <10^(-15)> g) for a near-infrared fluorescent dye. After sample separation by HPLC, we detected near-infrared dyes by semiconductor laser fluorimetry. The detection limit was 0.3 pg. We labeled protein in human serum with indocyanine green and separated by HPLC. By this method we could detect 1.3 pmol of albumin. In order to measure biological molecules, we developed a new analytical method based on near-infrared fluorimetry and enzyme reaction. We found that the fluorescence intensity of indocyanine green decreases with increasing the concentration of <H_2> <O_2> . Then, we could measure the activity of xanthine oxidase in the presence of xanthine. We could construct an analytical curve between 0-1 unit.2. Thermal lens spectrophotometry using optical fibers: In the near-infrared region absorption bands due to overtone vibrations are observed. We developed thermal lens spectrophotometry using a couple of optical fibers. The method using a multimode optical fiber has a good coupling efficiency but the output beam profile was very poor giving poor focal properties. Then, it was unsuitable for sensitive detection. On the other hand the method using a single mode optical fiber has a good spatial profile, and it was about 50 times more sensitive than conventional absorption spectrometry.