比光谱-导数-紫外分光光度法同时测定水中硝酸根和亚硝酸根

利用二元混合物的混合光谱与其中某一组分光谱的比值对波长求导，可达到分辨重叠光谱的目的。本文研究了用比光谱-导数-紫外分光光度法同时测定水样中NO3-和NO2-，以“减法技术”求导，兼具导数光度法能消除低频背景和高频噪声干扰及线性回归法分辨能力强的优点。方法避免了一般光度法需加入试剂而可能引起的误差。在pH7～9条件下测量203um～219um的光吸收值，用比光谱-导数技术处理，同时测定合成试样中0～4mg／L的NO3-和NO2-，6次测定相对标准偏差＜7％，加入回收率在95％～101％之间。讨论了干扰离子的影响及消除，并与P-矩阵法作了比较。方法已用于井水、雨水及湖水中NO3-和NO2-的同时测定。

Ratio Spectrum-Derivative Ultraviolet Spectrophotometry for Simultaneous Determination of NO_3~- and NO_2~- in Water

A ratio spectrum-derivative spctrophotometric method is studied for resolving the overlapped spectra of NO3- and NO2- The method is based on the use of the first derivative of the ratio spectrum obtained by dividing the absorption spectrum of the mixture by that of one of the component, then the concentration of the other component can be calculated. A subtraction technique is used for the derivation. In the range of pH 7~9, the absorbances are measured at the wavelengths from 203 to 219 nm, and the NO3- and NO2- can be deter mined simultaneously. The results obtained are compared with those obtained by the P-ma trix method. The method is very simple and has been applied to the determiriation of No3-and NO2- in water samples without preliminary separation.