1-(2-吡啶偶氮)-2-萘酚-过氧化氢光度法测定土壤中痕量钒
Photometric Determination of Trace Amounts of Vanadium by the Colour Reaction with 1-(2-Pyridylazo)-2-Naphthol and Hydrogen Peroxide
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摘要: 对钒(Ⅴ)与1-(2-吡啶偶氮)-2-萘酚-过氧化氢-十六烷基三甲基溴化铵显色反应进行了试验,结果表明:在1 mol·L-1盐酸介质中,在十六烷基三甲基溴化铵存在下,钒(Ⅴ)与1-(2-吡啶偶氮)-2-萘酚和过氧化氢反应生成红色多元络合物,络合物的最大吸收波长为577 nm,表观摩尔吸光率为3.04×104L·mol-1·cm-1,钒(Ⅴ)的质量浓度在1.0 mg·L-1以内符合比耳定律.络合物的组成比为n钒(Ⅴ)∶nPAN∶n过氧化氢=1∶1∶1.方法用于土壤试样中痕量钒的测定,测定值的相对标准偏差(n=6)均小于9%,回收率在97.8%~101.5%之间,测得标准样品(GSS-5)中钒的含量为170.45 μg·g-1,与标准值(166±9) μg·g-1之间的相对误差为2.7%.Abstract: It was found that in an acidic medium of 1 mol·L-1 HCl and in the presence of CTMAB,a ternary complex,with mole ratio of 1 to 1 to 1,was formed by the reaction of V(Ⅴ) with 1-(2-pyridylazo)-2-naphthol (PAN) and hydrogen peroxide,having its absorption maximum at the wavelength of 577 nm and the value of apparent molar absorptivity of 3.04×104L·mol-1·cm-1.Beer′s law was kept in the concentration range within 1.0 mg·L-1 of vanadium(Ⅴ).The proposed method was used for determination of vanadium in 4 samples of soil,including a standard sample (GSS-5).Values of RSD′s (n=6) found were less than 9%,and results of recovery found by standard addition method were in the range of 97.8%-101.5%.Relative error between results found for the standard sample (170.45 μg·g-1) and the certified value (166±9) μg·g-1 was 2.7%.