微量含氧酸根离子的分析一般采用分光光度法和荧光分析法,但因ppm级SO_4~(2-)的光度法测定缺乏灵敏的显色剂可用,因此,多采用BaSO_4是浮体的浊度法或比浊法进行测定。浊度法测定SO_4~(2+)时,由于胶体颗粒大小不同从而使透光的最大峰值波长不相同,所以,各位作者所报导的波长也不相同。我们选择最大吸收峰波长为3350A,无水粉术BaCl_2的加入量 Analysis of trace oxyacid ions generally spectrophotometry and fluorescence analysis, but the ppm level SO_4 ~ (2) of the spectrophotometric determination of the lack of sensitive reagent available, therefore, the use of BaSO_4 is the float of the turbidimetric method Or turbidimetric determination. Turbidity determination of SO_4 ~ (2+), due to the different colloidal particle size so that the maximum peak wavelength of light transmission is not the same, so the authors reported wavelength is not the same. We choose the maximum absorption peak wavelength of 3350A, anhydrous powder BaCl_2 amount added