石屏井水中金属元素的分析

Analysis of Metal Elements in Shiping Well Water

用原子吸收光谱法测定了云南省石屏县城用于直接点制豆腐的城内(北门、西门、南门)和城郊天然井水中Ca、Mg、Fe、Zn、Cu、Co、Cr、Ni和Cd等9种金属元素的含量,方法的相对标准偏差在0.28%—1.53%之间,回收率在97.68%—107.30%之间,分析结果满意。城中天然井水Ca和Mg含量非常高,Ca和Mg含量分别在207.83—268.50μg·mL-1和30.88—35.41μg·mL-1之间,其总硬度(以CaCO3计)在646.15—816.30μg·mL-1之间,为极硬水,西门外城郊井水中Ca含量仅为99.10μg·mL-1,Mg含量28.14μg·mL-1,都未检出Cd,其余6种金属元素在城中井水与郊外井水中的含量差别不大,且都较小;城中井水Ca、Mg含量:北门井水>西门井水>南门井水,井水中Ca和Mg含量在207.83、30.88μg·mL-1及其以上时,具有石膏或卤水凝固剂的作用,可直接点制豆腐;城中井水中Fe、Zn、Cu、Cr、Ni和Co含量大小为Fe>Zn>Cr>Ni>Cu>Co。

Nine metal elements,including Ca,Mg,Fe,Zn,Cu,Co,Cr,Ni,and Cd,in natural well water which is used to make tofu in Shiping city zone（north gate,west gate,south gate） and in outskirts of the city were determined simultaneously by atomic absorption spectrometry.The relative standard deviation of the method is 0.28%—1.53%,and the recovery is 97.68%—107.30%.The analytical results are satisfactory.The results indicate that the contents of Ca and Mg in the city zone are higher than these in the outskirts.The contents of Ca and Mg are in the range of 207.83—268.50μg·mL-1 and 30.88—35.41μg·mL-1,respectively,and the total hardness of the water （calculated from CaCO3） is very large,in the range of 646.15—816.30μg·mL-1,in the city zone well.However,the contents of Ca and Mg in the outskirts well are only 99.10μg·mL-1 and 28.14μg·mL-1,respectively.Cd could not be determined,and the contents of the other 6 elements are minor,and more or less the same in all the water.The descending order of Ca and Mg in the city zone well is north gate wellwest gate wellsouth gate well.When the contents of Ca and Mg are larger than 207.83μg·mL-1 and 30.88μg·mL-1 respectively,the water,which thus has the coagulating action like gypsum or bittern,can be used to make tofu directly.The descending order of the other 6 elements is FeZnCrNiCuCo in the city zone well.