同时测定水样中钙和镁的傅里叶变换滤波比值导数分光光度法

Simultaneous Determination of Calcium and Magnesium in Water by Fourier Transform Filtering and Ratio Spectra Derivative Spectrophotometry

提出了傅里叶变换滤波比值导数分光光度法 ,并以酸性铬蓝K作为显色剂 ,并把它当作一组分 ,而不是参比 ,对水中的钙和镁进行同时测定 ,这样可以减少由显色剂引起的误差;对所测的光谱进行傅里叶变换滤波 ,求混合体系光谱与显色剂光谱的比光谱 ,再对波长求导 ,然后对剩下的两组分中的一组分的光谱进行比值求导;经过上述处理后所得到的剩余组分的比光谱导数与其浓度成正比 ;虽然显色剂及钙和镁的配合物的吸收光谱严重重叠 ,但用该法对模拟水样及实际水样中钙和镁进行同时测定 ,结果令人满意 ,其加标回收率为92 %～103%。

A new spectrophotometric method based on Fourier transform filtering and derivation of ratio spectra is proposed for the simultaneous determination of calcium and magnesium. The analytical errors caused by the interference of the complexation reagent acid chrome blue K can be reduced by taking the reagent itself as a component of the system to be analyzed. The absorption spectra of all components in the system are filtered first with Fourier transform. A ratio spectrum is obtained by dividing the amplitudes of the absorption spectrum of the mixture by the spectrum of the acid chrome blue K. The first and second derivatives of the ratio spectrum are then obtained. The second derivative at a certain wavelength is proportional only to the concentration of one of the metal ions. The method has been applied to the simultaneous determination of Ca2+ and Mg2+ in both artificially blended samples and real water samples. The recovery was found to be in the range of 92%～103%.