化学发光法测定天然水体中低浓度硝酸盐和亚硝酸盐的含量

摘要

传统分光光度法测定硝酸盐和亚硝酸盐含量时检测限较高,无法测定部分海洋表层及寡营养盐海域低含量的硝酸盐和亚硝酸盐浓度,急需采用一种新的测定低浓度硝酸盐和亚硝酸盐的方法.化学发光法用于测定水体中硝酸盐和亚硝酸盐含量,具有灵敏度高、检测限低、样品用量少,不受悬浮颗粒物、有色物质影响及样品批量测定等优点.本文通过探索载气流速、反应温度、还原荆浓度及酸度等关键因素对反应信号值的影响,在实验室建立了用化学发光测定天然水体中硝酸盐和亚硝酸盐含量的方法,并确定了最佳实验条件.该方法测定水体中硝酸盐和亚硝酸盐浓度的检测限为10 nmol/L,当样品浓度为200、400 nmol/L时,精密度分别为5％和3％.%Chemiluminescent technique was applied for the determination of nanomolar quantities of nitrate and nitrite. Suspended particles and chromaphores did not interfere and were hence not necessary to be removed. The optimal experimental conditions with detection limit of 10 nmol/L were set up in the laboratory. The relative standard deviation was 5% at the 200 nmol/L level and 3% at the 400 nmol/L level. At wider detected range, greater accuracy and precision were obtained for this technique comparing to the conventional spectrophotometric methods. Consistent results were obtained when the concentrations of nitrate and nitrite in seawater and river water samples were measured using these two methods.