荧光光度法测定雨水中的H_2O_2含量

Determination of Hydrogen Peroxide in Rainwater by Fluorometry

研究了在pH4.48的HAc-NaAc缓冲溶液中,邻苯二胺(OPDA)与过氧化氢反应生成新物质2,3-二氨基吩嗪(DAPN)的荧光光谱变化,通过跟踪DAPN的荧光强度建立了过氧化氢测定的新方法,该方法由于采用二元体系,实验操作简单,灵敏度较高。实验结果表明,过氧化氢含量在9.0×10-7～3.6×10-5mol.L-1范围内与荧光强度的变化呈良好的线性关系,线性方程为:F=1.15c(μmol.L-1)+398.6,相关系数r=0.9991,最低检出限为2.7×10-7mol.L-1(3Ds/斜率,n=11)。对含量为7.5×10-6mol.L-1和3.0×10-5mol.L-1的H2O2的标准溶液进行了11次平行测定,其相对标准偏差分别为2.2%和1.0%。考察了多种共存离子的影响。该方法用于雨水中微量H2O2的测定,测定结果令人满意。

The present paper introduces a new method using spectrofluorimetric analysis to determine the concentration of hydrogen peroxide in rainwater. In this method, an oxidation reaction is conducted between o-phenylenediamine （OPDA） and hydrogen peroxide in the buffer medium of NaAc-HAc at pH 4. 48 to form a new product 2,3-diaminophenazine （DAPN）. Then the fluorescence intensity of DAPN is measured and 426 and 554 nm are chosen as the excitation and emission wavelengths. Therefore, with the foreknown concentration of input hydrogen peroxide, a series of fluorescence intensities of DAPN are acquired according to a series of different concentration of hydrogen peroxide as input, greatly improving the selectivity and sensibility of the systern. A relationship between the input concentration of hydrogen peroxide and the fluorescence intensity of DAPN is then obtained using a linear regression. Results show that fluorescence intensity of DAPN is in proportion to the increase in the concen- tration of hydrogen peroxide in the range of 9. 0×10-7～3.6×10-5mol.L-1 almost linearly. The linear equation is F=1.15c（μmol.L-1）＋398.6（r=0. 999 1） and the detection limit is 2.7×10^-7mol.L-1 （n=11）. The relative standard deviation of 11 parallel measurements with the concentration of H2O2 at 7. 5×10^-6 and 3.0×10-5mol.L-1 , is 2.2 and 1.0%, respectively. Results from DPD method was used to verify this method. The interference of foreign iron was studied. Compared to the traditional methods, this binary system has a simplified operation and high sensitivity. The proposed method has been successfully applied to determine the concentration of hydrogen peroxide in rainwater.