直接紫外分光光度法测定地下水中的硝酸盐氮

Determination of Nitrate Nitrogen in Groundwater by Direct Ultraviolet Spectrophotometry

未受有机污染的地下水的溶解物中,只有硝酸盐强吸收紫外光。对硝酸盐氮浓度在1—36mg/L的标样系列在220—240nm波长下的紫外吸收进行了测定,确定最佳测定波长为236nm。在此波长下,测得高、中、低3种浓度水样的精密度(RSD)分别为0.10%、0.22%、0.37%,加标回收率分别为98.3%、99.7%、102.0%。Cl-、SO42-、HCO3-等水中其他离子的干扰非常小。

In the groundwater without organic contaminant,nitrate is the only inorganic anion that have a very strong absorbance in the ultraviolet light. In the range of 1-36mg/L,the optimum detection wavelength is 236nm. The relative standard deviations （n=8） of the determination for the three different concentrations of the groundwater samples were 0. 10%, 0. 22% and 0. 37% with recoveries of 98. 3%, 99. 7% and 102. 0%, respectively. Other coexisted inorganic anions in the groundwater, such as Cl^-, SO4^2-, HCO3^-, were found to have very little interference in the determination.