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在含IO_3~-的0,5～lmol/L盐酸溶液中,用10mL双硫腙-四氯化碳溶液进行萃取时,IO_3~-能氧化双硫腙使其在有机相中的绿色减退。借反应前后有机相中双硫腙吸光度的改变,建立了一个测定痕量IO_3~-的方法。方法的灵敏度ε=1.7×10~5,最低检出限为1.75×10~(-8)g/mL IO_3~-线性范围0.175～6.15μg/10mLIO_3~-。对于能与双硫腙(H_2Dz)螯合的金属离子如Au~(3+)、Ag~+、Cu~(2+)、Cu~+、Hg~(2+)等的干扰,可将水相调至pH3～7,先用H_2Dz-CCl_4溶液萃取除去,在此条件下,H_2Dz不还原IO_3~-。方法用于KNO_3中IO_3~-的测定,得到了满意的结果。一、仪器与试剂
IO_3 ~ - 0,5 ~ lmol / L hydrochloric acid solution, with 10mL dithizone - carbon tetrachloride solution extraction, IO_3 ~ - oxidation of dithizone its green in the organic phase decreased. By the change of the absorbance of dithizone in the organic phase before and after the reaction, a method for the determination of trace IO_3 ~ - was established. The sensitivity of the method is 1.7 × 10 ~ 5, the minimum detection limit is 1.75 × 10 -8 g / mL IO_3 ~ - linear range of 0.175 ~ 6.15μg / 10mLIO_3 ~ -. For the interference of metal ions chelating with dithizone (H 2 Dz) such as Au ~ (3 +), Ag ~ +, Cu ~ (2+), Cu ~ +, Hg 2+, etc., Phase adjustment to pH3 ~ 7, first with H_2Dz-CCl_4 solution extraction and removal, under this condition, H_2Dz does not restore IO_3 ~ -. The method was applied to the determination of IO_3 ~ in KNO_3, and satisfactory results were obtained. First, equipment and reagents