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1 引言 在醋酸水溶液中及邻菲啰啉存在下,痕量Fe~(3+)对还原型罗丹明B(RRB)被MoO_4~(2-)氧化的反应有催化作用,据此建立了一个测定痕量铁的新的催化动力学分析方法。用于水样中铁的分析,结果与邻菲啰啉法和原子吸收法结果相接近。 2 实验部分 2.1 主要仪器 UV-250紫外可见分光光度计;722型分光光度计;AST-286计算机。 2.2 试验方法 于50ml比色管中依次加入0.1mol/L HAc 1.5ml,9.92×10~(-5)mol/L MoO_4~(2-)10ml,Fe~(3+)(1μg/ml)适量,0.15％邻菲啰啉5ml,加水稀释至25ml,混匀后放入沸水浴中,迅速加入3.2X10~(-4)mol/L的还原型罗丹明B 1.8ml,同时计时,发色6 min后,取出比色管,迅速加入2ml饱和EDTA,并用流水冷却以终止反应。3min后,在波长560nm处,使用1cm比色皿,以水为参比,于722型分光光度计上测吸光度值A,在同样的条件下,测非催化反应的吸光度值A_0,计算吸光度差值ΔA=A-A_0 3结果与讨论 3.1 吸收曲线 实验表明,产物最大吸收波长为560nm,邻菲啰啉的加入,未使最大吸收峰位移,只是降低了非催化反应的吸收峰。
1 Introduction In the presence of acetic acid and phenanthroline, a trace amount of Fe 3+ catalyzes the reaction of reduced rhodamine B (RRB) with MoO 4 2-, thus establishing a New Catalytic Kinetic Method for the Determination of Trace Iron. For water samples of iron analysis, the results and phenanthroline method and atomic absorption method results are close. 2 Experimental 2.1 The main instrument UV-250 UV-visible spectrophotometer; 722 spectrophotometer; AST-286 computer. 2.2 Test Method In 50ml colorimetric tube were added 0.1mol / L HAc 1.5ml, 9.92 × 10 ~ (-5) mol / L MoO_4 ~ (2-) 10ml, Fe ~ (3 +) (1μg / ml) , 0.15% orthophenanthroline 5ml, diluted with water to 25ml, mix well into a boiling water bath, quickly added 3.2X10 ~ (-4) mol / L of reduced rhodamine B 1.8ml, at the same time, hair color 6 min, remove the colorimetric tube, quickly add 2ml saturated EDTA, and cooled with running water to terminate the reaction. 3min later, at a wavelength of 560nm, the use of 1cm cuvette, water as a reference, measured on a 722 spectrophotometer absorbance value A, under the same conditions, the measured non-catalytic reaction absorbance value A_0 absorbance differential The value of ΔA = A-A_0 3 Results and discussion 3.1 Absorption curve Experiments show that the maximum absorption wavelength of the product 560nm, phenanthroline addition, did not shift the maximum absorption peak, but reduced the non-catalytic reaction absorption peak.