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研究了在H2 SO4 介质中 ,氯离子存在下 ,用甲苯萃取二甲基吲哚羰花青 (DIC)染料与Cr(Ⅵ )配合物的显色反应。基于此 ,建立了一种光度法测定微量Cr(Ⅵ )的新方法。结果表明在 0 .0 5～ 0 .3mol L的H2 SO4 介质中 ,甲苯对配合物的萃取率最高。最大吸收波长为 5 60nm ,摩尔吸光系数为 2 .5×1 0 5L·mol-1·cm-1,检出限为 4× 1 0 -9g mL ,有色溶液的吸光度与Cr(Ⅵ )量在 0 .0 1～ 2 .1mg L范围内符合比尔定律 ,加标回收率为 96.4 %～ 1 0 4 .8% (n =6) ,n(Cr(Ⅵ ) ) :n(Cl-)∶n(DIC) =1∶1∶1。本法满意地测定了非晶态FeNiCr合金中的铬
The color reaction of dimethyl indocyanine carbocyanine (DIC) with Cr (Ⅵ) with toluene was studied in the presence of chloride ion in H2 SO4 medium. Based on this, a new method of spectrophotometric determination of trace Cr (Ⅵ) was established. The results showed that the extraction yield of toluene was the highest among 0.05 mol% H2 SO4 in toluene. The maximum absorption wavelength was 5 60nm, the molar absorptivity was 2.5 × 105 L · mol-1 · cm-1, the detection limit was 4 × 10 -9 g mL. The absorbance of the colored solution and the Cr (Ⅵ) The Beer’s law was obeyed in the range of 0 1 ~ 2 .1 mg L, and the recoveries were 96.4% -1.04% (n = 6), n (Cr (Ⅵ)): n (DIC) = 1: 1: 1. This method is satisfactory for the determination of chromium in amorphous FeNiCr alloys