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在酸性条件下,Cr(能将二苯碳酰二肼(DPC)氧化成紫红色二苯偶氮碳酰,自身被还原为Cr(Ⅲ),Cr(Ⅲ)可与二苯偶氮碳酰生成深紫红色Cr(Ⅲ)-二苯偶氮碳酰络合物,该络合物在水相中不易溶解且不稳定,而在有机溶剂苯中稳定且极易溶解,用N2将Cr(Ⅲ)-二苯偶氮碳酰络合物浮选于苯中,形成真溶液,通过测定有机相吸光度测定溶液中Cr(含量。通过用过硫酸铵将溶液中Cr(Ⅲ)氧化成Cr(可测定Cr(和Cr(Ⅲ)合量(∑Cr),差减法计算出Cr(Ⅲ)含量。由于采用了大剂量富集倍数,使灵敏度大大提高,ε540=4.2×105,比水相光度法提高10倍。50 mL溶液中,Cr(质量线性范围0~12μg,测定5.0μg Cr(,RSD=1.8%(n=6),方法检出限7.1×10-9mol/L。由于络合和浮选的选择性,使本法选择性大大提高,实测了天然水中Cr(和Cr(Ⅲ),结果令人满意。
Under acidic conditions, Cr (which oxidizes diphenylcarbazide (DPC) to fuchsine diphenylcarbazone itself is reduced to Cr (III), which can react with diphenylazocarbonyl The clarithromycin (Cr (III)) - diphenylcarbazone complex was formed. The complex was not easily dissolved and unstable in the aqueous phase, but stable and easily dissolved in organic solvent benzene. Cr Ⅲ) - diphenylcarbazole complex flotation in benzene to form a true solution, the determination of the organic phase by measuring the absorbance of Cr (content by using ammonium persulfate solution Cr (Ⅲ) into Cr (Ⅲ) Cr (¢ ó) and Cr (¢ ó) can be determined, and the Cr (¢ ó) content can be calculated by the subtraction method.As a result of the large dose enrichment factor, the sensitivity is greatly improved, ε540 = 4.2 × 105, Method, the detection limit of Cr was 7.1 × 10-9mol / L for Cr (linear range of 0 ~ 12μg, 5.0μg Cr (RSD = 1.8%, n = 6) And flotation selectivity, the selectivity of the law greatly increased, measured in natural water Cr (and Cr (Ⅲ), the results are satisfactory.