Zn(Ⅱ)-1,10-phen-EY体系褪色光度法测定微量锌

Color-Fading-Photometric Determination of Trace Zinc with Zn (Ⅱ)-1,10-phen-EY System

在pH=3.78的BR缓冲溶液中,1,10-邻菲啰啉(phen)与锌(Ⅱ)形成螯合阳离子后,再进一步与曙红Y(EY)通过静电引力和疏水作用力形成离子缔合物,引起吸收光谱的变化,最大褪色波长位于516 nm,另在548 nm处产生新的吸收峰.考察了最佳的反应条件、光谱特征及方法的灵敏度与选择性,研究发现,Zn(Ⅱ)在2.0×10-6～1.0×10-4mol.L-1的浓度范围内遵守郎伯比尔定律,方法的灵敏度高,摩尔吸收系数ε为7.003×104L.mol-1.cm-1,且具有良好的选择性,对大多数离子的允许量都较大.用于实际样品的测定,结果令人满意.据此建立了一种新的测定微量锌的方法.

In pH = 3.78 BR buffer solution,1,10-Phenanthroline monohydrate（phen） and zinc（Ⅱ） form chelate cation.They can further react with eosin Y（EY） through electrostatic forces and hydrophobic forces,which causes the change of the absorption spectrum and produces obviously color-fading.The maximum color-fading wavelength at 516nm and the other new absorption peak at 548 nm.The spectral characteristics of the system and the optimum conditions for the reactions are investigated.The intensity of absorbance is directly proportional to the concentration of trace zinc in the certain concentration range.The method has a high sensitivity,ε is 7.003 × 104L.mol-1.cm-1.In this case,most metal and non-metal ions do not interfere,so that the method has a good selectivity.The method has been applied to the determination of trace zinc,the result is satisfying.Therefore,a new method is developed to determine trace zinc.