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

采用半导体激光器（SCL）和薄长通流池（TLFCT）的高灵敏度检测系统可以匹配流动分析，如流动注射分析（FIA）。SCL是发射波长为780nm （5mW）的GaAIAs半导体激光器，TLFTC由聚四氟乙烯（PTFE）棒制成，具有100mm长的细光路。灵敏度基本上提高了大约10倍，与通常的fia分光光度法相比，使用10毫米传统的流动池。将该检测系统应用于钼蓝分光光度法测定水中总磷(P)，相对标准偏差为1.0%(20马克杯P 1^<-1>时n=10)，检出限为0.6（3西格玛），线性范围为1.0-50马克杯P 1^<-1>时，样品结果与官方方法基本一致。也可以将本检测系统应用于其他基于流动的分析方法，如液相色谱家族。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。该检测系统还可以对样品中的其他痕量成分进行FLA检测。SCL的技术正在迅速发展。输出功率每年翻一番，而成本却降低了一半。为了进一步提高灵敏度，TLFTC的光程可以进一步延长。当一种价格低廉、频率可连续调节的SCL出现时，使用这种分析技术将更加适合和方便样品中许多痕量成分的测定。新的检测系统也可能有利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.