An automatic analyzer coupled with a versatile liquid waveguide capillary cell (LWCC) of different lengths for long-term in situ monitoring of nitrite in seawater was developed based on sequential injection analysis and spectrophotometry. Laboratory experiments have been carried out to analyze the impact of system parameters and environmental factors to obtain the optimal in situ detection performance of the analyzer. By utilizing 10 cm and 50 cm LWCCs, the analyzer can detect nitrite ([NO₂⁻]) concentrations from 0.063 to 6.5 μM and 0.025 to 0.5 μM, and reach detection limits of 0.0189 μM and 0.0076 μM respectively. The short optical path (10 cm) analyzer was tested in situ during a scientific research cruise and then deployed at a coastal experiment station for one month to test the analyzer long-term measurement reliability and monitor nitrite temporal variation. The long optical path (50 cm) analyzer was deployed in a low nutrient coral reef waters over 50 days and the CTD, turbidity, dissolved oxygen and chlorophyll a data were synchronously acquired through a multi-parameter probe, and the distinct relationship between the in situ monitoring results was discussed.

基于顺序注入分析和分光光度法，开发了一种自动分析仪，与不同长度的多功能液体波导毛细管（LWCC）相结合，用于长期原位监测海水中的亚硝酸盐。进行了实验室实验，分析了系统参数和环境因素的影响，以获得分析仪的最佳原位检测性能。通过利用 10 cm 和 50 cm LWCC，分析仪可以检测亚硝酸盐（[NO₂^-]) 浓度范围为 0.063 至 6.5 μM 和 0.025 至 0.5 μM，并分别达到 0.0189 μM 和 0.0076 μM 的检测限。短光程（10 cm）分析仪在一次科研巡航期间进行了现场测试，然后在沿海实验站部署了一个月，以测试分析仪的长期测量可靠性并监测亚硝酸盐的时间变化。长光程（50 cm）分析仪在低营养珊瑚礁水域部署超过50天，通过多参数探头同步获取CTD、浊度、溶解氧和叶绿素a数据，并在现场监测结果进行了讨论。