愈创木酚催化光度法测定痕量铁(Ⅲ)

Photometric Determination of Traces of Iron(Ⅲ) Based on Its Catalytic Action on Oxidation of Guaiacol by Potassium Periodate

在pH 2.6的邻苯二甲酸氢钾-盐酸缓冲溶液中,在活化剂邻菲啰啉存在下,研究了痕量铁(Ⅲ)对高碘酸钾氧化愈创木酚反应的催化作用,并测定了此反应的动力学参数。于两个25 mL具塞比色管中各加0.30mol·L^(-1)愈创木酚溶液0.6mL,缓冲溶液1.5mL,1×10^(-3)mol·L^(-1)邻菲啰啉溶液2 mL及0.03mol·L^(-1)高碘酸钾溶液3mL,于其中一份中加入定量的铁(Ⅲ)溶液,另一份不加,加水定容后置于60℃±5℃水浴中加热6min,冷却后于480nm波长处测量两溶液的吸光度A及A_0,并计算△A。△A值与铁(Ⅲ)的质量浓度在0.2～2.0μg·L^(-1)范围内呈线性关系,其检出限(3S/N)为2.3×10^(-2)μg·L^(-1)。按此方法测定了纯水、矿泉水、红酒及啤酒样品中铁量,所得结果与火焰原子吸收光谱法的结果相符,测定值的相对标准偏差(n=6)在0.51%～2.1%之间。

In a phthalate buffer medium of pH 2. 6 and in the presence of o-phenanthroline as activator, catalytic action of Fe（ Ⅲ ） on the oxidation of guaiacol by KIO4 was studied and its kinetic parameters were tested. The reaction mixtures in two 25 mL volumetric flasks containing in one flask 0. 30 mol .L^-1 guaiacol solution 0. 6 mL, phthalate buffer solution 1. 5 mL, 1 × 10^-3 mol . L-1 o-phenanthroline solution 2 mL, 0. 03 mol. L^-1 KIO4 solution 3 mL and a definite amount of Fe（ Ⅲ ）, and in the another flask the same reagents but without Fe（ Ⅲ ）, were heated after diluting to 25 mL in a water bath at 60 ℃ ±0. 5 ℃ for 6 min. The values of absorbance of both solutions were taken at the wavelength of 480 nm and △A was calculated by A-A0. Linear relationship between values of zXA and mass concentration of Fe（Ⅲ） was kept in the range of 0. 2-2. 0μg . L-1 , with detection limit （3S/N） of 2.3× 10^-2μg .L-1. Samples of pure water, mineral water, grape wine and beer were analyzed by this method for their Fe（ Ⅲ） contents, the results obtained were in conformity with the results found by FAAS, and values of RSD＇s（n=6） found were in the range of 0. 51%-2. 1%.