我国的水资源环境问题日益严峻，已直接或间接的影响到了人类健康。水质自动监测系统可以实现对水质的连续实时监测和远程监控，及时掌握主要流域重点断面水体的水质状况，同时还可以预报预警重大或流域性水质污染事故，可有效地加强水环境的监测和管理工作。我国环境监测仪器设备与国际先进水平有一定差距，小型化、智能化是我国监测仪器的研发趋势，也是提高自动监测系统水平的关键因素。

      本研究基于顺序注射技术和分光光度法的原理，设计研发了一台小型顺序注射仪器，并应用于环境水样中常见污染物亚硝酸盐（NO2-）和六价铬Cr（VI）的检测。该仪器具有精密度高、检出限低、准确度高、操作便捷、抗干扰能力强等优点，适用于全自动在线实时检测，在环境分析监测领域具有很好的应用前景。具体的研究内容如下：

     1.基于改进的顺序注射技术结合分光光度法，设计研发了一台小型顺序注射仪器。研发的技术路线包括仪器的结构设计、仪器的自动化设计和仪器的后期调校和优化。其中结构设计包括仪器的检测原理、仪器的流路图设计和硬件的选择搭建。仪器的自动化设计包括电路控制系的设计、可编程控制器的编程和用户交互界面的设计。仪器后期的调校和优化包括仪器的进样比例、顺序以及物理参数的优化。

     3.将仪器应用于环境水样中Cr（VI）的检测。对反应时间、载流液中硫酸和磷酸的量、显色剂中丙酮的加入量和二苯碳酰二肼（DPC）的浓度进行优化。在最优化条件下，Cr（VI）线性检测范围是5–1000 µg·L-1，检出限为2.12 µg·L-1，相对标准偏差1.69%，实际水样的加标回收率在92.2%–128.0%之间。

     The increasingly serious problem of water environment has direct or indirect impact on human health in our country.Implementation of water quality automatic monitoring can realize continuous real-time monitoring and remote monitoring of water quality, grasp the major river basin section of water quality conditions timely, and forecast major or basin water pollution accidents, though which can strengthen the monitoring and management effectively. In our country, the environmental monitoring instruments still lag behind the international advanced level. The research trends of monitoring instruments are miniaturization and intelligentization, which are the key factor of improving the level of automatic monitoring system.

     The study based on sequential injection technique and the principle of spectrophotometry, developed a small sequential injection machine, which was applied to the detection of common pollutants nitrite (NO2-) and Cr (VI) in environmental water samples. The instrument with high precision, low detection limit, high accuracy and easy maneuverability, anti-jamming ability, is suitable for automatically online real-time detection; therefore it has a very good prospect for environmental analysis and monitoring. The contents of this thesis are as follows:

    1. Based on the improved sequential injection technique combined with the spectrophotometric method, we developed a small sequential injection machine. The technical route of research involved structure design, automation design, calibration and optimization. Structure design included testing principle, flow chart design and hardware selection. Automation design contained the design of the circuit control system, programmable controller programming and user interface design. Calibration and optimization comprised the proportion、orders of sampling and the physical parameters.

    2. The instrument was applied to analysis of NO2- in environmental water samples. The reaction time, the amount of phosphate, concentrations of sulfanilamide (SA) and the N- (1-naphthyl) ethylene diamine dihydrochloride (NED 2HCl) were optimized. Under the optimized conditions, NO2- linear range of 3–1000 µg·L-1, the detection limit of 1.05 µg·L-1, relative standard deviation of 1.23% and recovery rate of 105.4%–122.1% were achieved.

   3. The instrument was applied to analysis of Cr (VI) in environmental water samples. The reaction time, the volume of sulfuric acid and phosphoric acid in the carrying water, the volume of acetone and concentration of diphenyl carbonyl hydrazine (DPC) in the chromogenic agent were optimized. Under the conditions of optimization, Cr (VI) linear range of 5–1000 µg·L-1, the detection limit of 2.12 µg·L-1, relative standard deviation of 1.69% and recovery rate of 92.2%–128.0% were obtained.