流动注射-分光光度法测定河口水中氨氮的盐效应及校正

Establishing a Method to Study Salt Effect of Ammonia in Estuarine Water with Flow Injection Spectrophotometry

建立了流动注射-分光光度法测定河口水中氨氮的盐效应的校正办法。样品溶液中的钙离子、镁离子是造成盐效应的主要因素。低盐区域(盐度0~10)随盐度增加,校正系数迅速降低;高盐区域(盐度10~30)随盐度增加,校正系数缓慢增加。氨氮的线性范围为3.00~300μg·L-1,方法的检出限(3S/N)为1.97μg·L-1。对20.0μg·L-1氨氮标准溶液连续测定7次,测定值的相对标准偏差为4.5%。用标准加入法做方法的回收试验,测得回收率在80.7%~108%之间。

This experiment aims to establish a correction method to study salt effect of ammonia in estuarine water with flow injection spectrophotometry.The experiment result suggests that salt effect is largely contributed by Ca2+and Mg2+in the solution.In low salt concentration(salinity from 0to 10),correction coefficient decreased rapidly with increase in salinity;in high salt concentration(salinity from 10 to 30),correction coefficient increased slowly with increase in salinity.Linearity range of ammonia was found in the range of 3.00-300μg·L-1 with detection limit(3S/N)of 1.97μg·L-1.Precision of the method was tested at the concentration level of 20.0μg·L-1 ammonia standard solution for 7 determination,value of RSD found was 4.5%.Test for recovery was performed by standard addition method,giving values of recovery in the range of 80.7%-108%.