氰化渣中痕量钯的微波消化-固相萃取光度法的研究

STUDY ON THE SOLID-PHASE PHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF PALLADIUM IN CYANIDE SLAG——SAMPLE-DIGESTION BY MICROWAVE-HEATING

合成了新试剂2-(2'-喹啉偶氮)-5-二乙氨基苯甲酸(QADEAB),试验了该试剂与钯(Ⅱ)的显色反应及C18固相萃取小柱对显色配合物的固相萃取.钯(Ⅱ)在pH 2.5的氯乙酸-氢氧化钠缓冲介质中,溴化十六烷基三甲胺(CTMAB)存在下与QADEAB生成1:2稳定配合物.该配合物可被C18小柱萃取富集,富集的配合物用乙醇洗脱;富集倍数达50倍,洗脱液经定容后用光度法测定.最大吸收波长为635 nm,ε=1.53×105L·mol-1·cm-1,钯(Ⅱ)含量在0.01～1.5 mg·L-1内符合比耳定律.该方法用于氰化渣中钯含量的测定,结果满意.

A new color reagent, 2-（2＇-quinolinylazo）-5-diethylamino-benzoic acid （abbreviated as QADEAB） was synthesized and its color reaction with palladium（ Ⅱ ） was studied. In a chloroacetate buffer of pH 2.5, and in the presence of CTMAB, a stable colored-complex （R ： Pd=2 ： 1） was formed. It was found that the colored complex can be extracted and preconcentrated on a small C18 column, and can be stripped from the column with ethyl alcohol. The rate of concentration obtained was about 50 times. The colored complex when stripped with 2.0 mL of ethyl alcohol showed an absorption maxima at 635 nm and a molar absorptivity （ε） of 1.53× 10^5L· mol^-1 · cm^-1. Beer＇s law was held in the range of 0. 01- 1.5 mg of Pd（Ⅱ ） per liter of solution. The above mentioned color reaction was applied to the photometric determination of traces of Pd（ Ⅱ ） in cyanide slag samples, after dissolution of sample with HNO3-HCl mixture in a PTFE flask heated in a microwave oven.