Development of Photometric Flow Analyzer with Laser Diode and Long Flow Cell

开发了一种使用半导体激光器(SCL)和细长流通池(TLFCT)来匹配流动注射分析(FIA)等基于流动分析的高灵敏度检测系统。SCL是发射波长为780 nm(5 MW)的GaAIAS半导体激光器，TLFTC由聚四氟乙烯(PTFE)棒制成，具有100 mm长的光路。与通常使用10 mm常规流动池的流动注射分光光度法相比，灵敏度基本上提高了约10倍。将该检测系统应用于钼蓝分光光度法测定水中总磷，相对标准偏差为1.0%(n=10)，检出限为0.6(3sigma)，线性范围为1.0~50µg，测定结果与官方方法基本一致。本检测系统还可以应用于其他流动分析方法，如高效液相色谱仪系列。水中溶解二氧化硅的测定是该检测系统在实际痕量分析中的应用之一。利用该检测系统，样品中的其他痕量组分也可以用火焰原子吸收光谱仪进行测定。SCL的技术正在迅速发展。输出功率每年翻一番，成本减少一半。TLFTC的光程长度可以进一步延长，以进一步提高灵敏度。当一种价格低廉、频率可连续可调的化学发光二极管问世时，使用这一分析技术将更加适合和方便地测定样品中的许多痕量组分。新的检测系统也可能有益于其他基于流动的分析技术，如液相色谱。

A highly sensitive detection system using a semiconductor laser (SCL) and a thin long flow-through cell (TLFCT) to match flow-based analysis, such as flow injection analysis (FIA), has been developed. The SCL was a GaAIAs semiconductor laser emitting at 780 nm (5mW), and the TLFTC,which has a 100 mm thin long light path, was made of a poly (tetrafluoroethylene) (PTFE) rod. The sensitivity was essentially improved about 10-fold in comparison to usual FIA-spectrophotometry using a 10 mm conventional flow cell. When this detection system was applied to the determination of total phosphorus (P) in water by molybdenum-blue spectrophotometry, the relative standard deviation, detection limit and linear range were 1.0% (n=10 at 20 mug P 1^<-1>), 0.6 (3sigma) and 1.0-50 mug P 1^<-1>, respectively, and the results for the samples were fairly consistent with those by the official method. It may also be possible to apply the present detection system to other flow-based analytical methods such as the liquid chromatography family.The determination of dissolved silica in waters is one of the applications of the detection system to practical trace analysis. Other trace components in samples could also be measured by FLA with this detection system. The technology of the SCL is progressing rapidly. The output power doubles every year, and the cost is cut in half. The light pathlength of TLFTC may be further prolonged for further increasing the sensitivity. When an inexpensive SCL,which can be continuously adjustable in frequency, comes available, it will be ever more suitable and convenient for determinations of many trace components in samples to use this analytical technique. The new detection system may also be beneficial to other flow-based analytical techniques such as liquid chromatography.